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<span class="vector-toc-numb">1.3</span> <span>Variants</span> </div> </a> <ul id="toc-Variants-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Gas-operated_models" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Gas-operated_models"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Gas-operated models</span> </div> </a> <ul id="toc-Gas-operated_models-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>References</span> </div> </a> <button aria-controls="toc-References-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle References subsection</span> </button> <ul id="toc-References-sublist" class="vector-toc-list"> <li id="toc-Bibliography" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Bibliography"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Bibliography</span> </div> </a> <ul id="toc-Bibliography-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>External links</span> </div> </a> <ul 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Available in 22 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-22" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">22 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/20_mm_%D0%BE%D1%80%D1%8A%D0%B4%D0%B8%D0%B5_Oerlikon" title="20 mm оръдие Oerlikon – Bulgarian" lang="bg" hreflang="bg" data-title="20 mm оръдие Oerlikon" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/20mm_kan%C3%B3n_Oerlikon" title="20mm kanón Oerlikon – Czech" lang="cs" hreflang="cs" data-title="20mm kanón Oerlikon" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/20-mm-Oerlikon-Kanone" title="20-mm-Oerlikon-Kanone – German" lang="de" hreflang="de" data-title="20-mm-Oerlikon-Kanone" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Estonian" lang="et" hreflang="et" data-title="Oerlikon 20 mm" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Spanish" lang="es" hreflang="es" data-title="Oerlikon 20 mm" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D9%88%D9%BE_%DB%B2%DB%B0_%D9%85%DB%8C%D9%84%DB%8C%E2%80%8C%D9%85%D8%AA%D8%B1%DB%8C_%D8%A7%D9%88%D8%B1%D9%84%DB%8C%DA%A9%D9%86" title="توپ ۲۰ میلی‌متری اورلیکن – Persian" lang="fa" hreflang="fa" data-title="توپ ۲۰ میلی‌متری اورلیکن" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Canon_de_20_mm_Oerlikon" title="Canon de 20 mm Oerlikon – French" lang="fr" hreflang="fr" data-title="Canon de 20 mm Oerlikon" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Meriam_Oerlikon_20_mm" title="Meriam Oerlikon 20 mm – Indonesian" lang="id" hreflang="id" data-title="Meriam Oerlikon 20 mm" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/20_mm_Oerlikon" title="20 mm Oerlikon – Italian" lang="it" hreflang="it" data-title="20 mm Oerlikon" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%AA%D7%95%D7%AA%D7%97_%D7%90%D7%95%D7%A8%D7%9C%D7%99%D7%A7%D7%95%D7%9F" title="תותח אורליקון – Hebrew" lang="he" hreflang="he" data-title="תותח אורליקון" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Meriam_20_mm_Oerlikon" title="Meriam 20 mm Oerlikon – Malay" lang="ms" hreflang="ms" data-title="Meriam 20 mm Oerlikon" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Dutch" lang="nl" hreflang="nl" data-title="Oerlikon 20 mm" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%A8%E3%83%AA%E3%82%B3%E3%83%B3_20_mm_%E6%A9%9F%E9%96%A2%E7%A0%B2" title="エリコン 20 mm 機関砲 – Japanese" lang="ja" hreflang="ja" data-title="エリコン 20 mm 機関砲" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Oerlikon_20_mm_maskinkanon" title="Oerlikon 20 mm maskinkanon – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Oerlikon 20 mm maskinkanon" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/20_mm_Oerlikon" title="20 mm Oerlikon – Polish" lang="pl" hreflang="pl" data-title="20 mm Oerlikon" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Portuguese" lang="pt" hreflang="pt" data-title="Oerlikon 20 mm" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/20-%D0%BC%D0%BC_%D0%BF%D1%83%D1%88%D0%BA%D0%B8_%C2%AB%D0%AD%D1%80%D0%BB%D0%B8%D0%BA%D0%BE%D0%BD%C2%BB" title="20-мм пушки «Эрликон» – Russian" lang="ru" hreflang="ru" data-title="20-мм пушки «Эрликон»" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Slovenian" lang="sl" hreflang="sl" data-title="Oerlikon 20 mm" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Oerlikon_20_mm" title="Oerlikon 20 mm – Finnish" lang="fi" hreflang="fi" data-title="Oerlikon 20 mm" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/20-%D0%BC%D0%BC_%D0%B7%D0%B5%D0%BD%D1%96%D1%82%D0%BD%D0%B0_%D0%B3%D0%B0%D1%80%D0%BC%D0%B0%D1%82%D0%B0_%C2%AB%D0%95%D1%80%D0%BB%D1%96%D0%BA%D0%BE%D0%BD%C2%BB" title="20-мм зенітна гармата «Ерлікон» – Ukrainian" lang="uk" hreflang="uk" data-title="20-мм зенітна гармата «Ерлікон»" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E5%8E%84%E5%88%A9%E5%AD%9420%E6%AF%AB%E7%B1%B3%E6%A9%9F%E7%82%AE" title="厄利孔20毫米機炮 – Cantonese" lang="yue" hreflang="yue" data-title="厄利孔20毫米機炮" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%A5%A7%E7%91%9E%E5%B2%A120%E5%85%AC%E9%87%90%E6%A9%9F%E7%82%AE" title="奧瑞岡20公釐機炮 – Chinese" lang="zh" hreflang="zh" data-title="奧瑞岡20公釐機炮" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a 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dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Series of autocannons</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox vcard" style="width:25.5em;border-spacing:2px;"><tbody><tr><th colspan="2" class="infobox-above hproduct" style="background-color:#C3D6EF;color:inherit;text-align:center;vertical-align:middle;font-size:110%;"><span class="fn org"> Oerlikon 20 mm cannon </span></th></tr><tr><td colspan="2" class="infobox-image" style="text-align:center;border-bottom:1px solid #aaa;line-height:1.5em;"><span typeof="mw:File"><a href="/wiki/File:Oerlikon_20mm_2.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/2/2b/Oerlikon_20mm_2.jpg" decoding="async" width="300" height="274" class="mw-file-element" data-file-width="274" data-file-height="250" /></a></span><div class="infobox-caption">Oerlikon 20 mm cannon in <a href="/wiki/French_Navy" title="French Navy">French</a> service</div></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Type</th><td class="infobox-data"><a href="/wiki/Autocannon" title="Autocannon">Autocannon</a></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Place of origin</th><td class="infobox-data">Switzerland</td></tr><tr><th colspan="2" class="infobox-header" style="background-color:#C3D6EF;color:inherit;text-align:center;vertical-align:middle;font-size:110%;">Service history</th></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">In service</th><td class="infobox-data">1937–present</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Used by</th><td class="infobox-data">Various</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Wars</th><td class="infobox-data"><a href="/wiki/World_War_II" title="World War II">World War II</a>, various</td></tr><tr><th colspan="2" class="infobox-header" style="background-color:#C3D6EF;color:inherit;text-align:center;vertical-align:middle;font-size:110%;">Production history</th></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Designer</th><td class="infobox-data">Reinhold Becker</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Designed</th><td class="infobox-data">1935</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Manufacturer</th><td class="infobox-data"><a href="/wiki/Oerlikon_Contraves" class="mw-redirect" title="Oerlikon Contraves">Oerlikon</a></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Produced</th><td class="infobox-data">1937–</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><abbr title="Number">No.</abbr> built</th><td class="infobox-data">124,734<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Variants</th><td class="infobox-data"><a href="/wiki/Oerlikon_FF" title="Oerlikon FF">Oerlikon FF</a><br /><a href="/wiki/MG_FF_cannon" title="MG FF cannon">MG FF cannon</a></td></tr><tr><th colspan="2" class="infobox-header" style="background-color:#C3D6EF;color:inherit;text-align:center;vertical-align:middle;font-size:110%;">Specifications</th></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Mass</th><td class="infobox-data"><b>L70</b><br />Total gun barrel weight: 68.04 <a href="/wiki/Kilogram" title="Kilogram">kilograms</a> (150.0 <a href="/wiki/Pound_(mass)" title="Pound (mass)">lb</a>)<br />Minus breech mechanism: 20.865 kg (46.00 lb)<br /><b>L85</b><br />Empty: 92.0 <a href="/wiki/Kilogram" title="Kilogram">kilograms</a> (202.8 <a href="/wiki/Pound_(mass)" title="Pound (mass)">lb</a>)<br />Loaded with 200 rounds: 182.0 kg (401.2 lb)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Length</th><td class="infobox-data"><b>L70</b><br />Overall: 2,210 mm (87 in)<br />Barrel length: 1,400 mm (55 in)<br /><b>L85</b><br />Overall: n/a<br />Barrel length: 1,700 mm (67 in)</td></tr><tr><td colspan="2" class="infobox-full-data"><hr /></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Shell_(projectile)" title="Shell (projectile)">Shell</a></th><td class="infobox-data"><b>L70:</b> 20×110mmRB<br /><b>L85:</b> 20×128mm</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Shell_(projectile)" title="Shell (projectile)">Shell</a> weight</th><td class="infobox-data"><b>HE:</b> 123 g (4.3 oz)<br /><b>HE/T:</b> 116 g (4.1 oz)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Caliber" title="Caliber">Caliber</a></th><td class="infobox-data">20 mm (0.787inch)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Barrels</th><td class="infobox-data">Single barrel (progressive RH parabolic twist, 9 grooves)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Action_(firearms)" title="Action (firearms)">Action</a></th><td class="infobox-data"><a href="/wiki/Advanced_Primer_Ignition" class="mw-redirect" title="Advanced Primer Ignition">API blowback</a></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Elevation_(ballistics)" title="Elevation (ballistics)">Elevation</a></th><td class="infobox-data">Manual, -15°/+90°</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Gun_laying" title="Gun laying">Traverse</a></th><td class="infobox-data">Manual, full 360°</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Rate_of_fire" title="Rate of fire">Rate of fire</a></th><td class="infobox-data"><b>L70:</b><br />Cyclic: 450 rounds per minute<br />Practical: 250-320 rounds per minute<br /><b>L85:</b><br />Cyclic: 900 to 1,000 rounds per minute</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em"><a href="/wiki/Muzzle_velocity" title="Muzzle velocity">Muzzle velocity</a></th><td class="infobox-data"><b>L70:</b> 820 m/s (2,700 ft/s)<br /><b>L85:</b> 1,050 m/s (3,400 ft/s)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Effective firing range</th><td class="infobox-data">Against low-flying aircraft (HE round)<br /><b>L70:</b> 914 m (1,000 yd)<br /><b>L85:</b> 1,500 m (1,600 yd)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Maximum firing range</th><td class="infobox-data">HE round at 45°<br /><b>L70:</b> 4,389 m (4,800 yd)<br /><b>L85:</b> 6,800 m (7,400 yd)</td></tr><tr><th scope="row" class="infobox-label" style="padding-right:1em">Feed system</th><td class="infobox-data">Cylindrical magazine holding 60 rounds, Later adjusted to be a belt fed gun</td></tr></tbody></table> <p>The <b>Oerlikon 20 mm cannon</b> is a series of <a href="/wiki/Autocannon" title="Autocannon">autocannons</a> based on an original German <a href="/wiki/Becker_Type_M2_20_mm_cannon" title="Becker Type M2 20 mm cannon">Becker Type M2 20 mm cannon</a> design that appeared very early in <a href="/wiki/World_War_I" title="World War I">World War I</a>. It was widely produced by <a href="/wiki/Oerlikon_Contraves" class="mw-redirect" title="Oerlikon Contraves">Oerlikon Contraves</a> and others, with various models employed by both Allied and Axis forces during <a href="/wiki/World_War_II" title="World War II">World War II</a>. Many versions of the cannon are still used.<sup id="cite_ref-NAVWEAP1_2-0" class="reference"><a href="#cite_note-NAVWEAP1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NAVWEAP2_3-0" class="reference"><a href="#cite_note-NAVWEAP2-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Blowback-operated_models">Blowback-operated models</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=1" title="Edit section: Blowback-operated models"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="History">History</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=2" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Origins">Origins</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=3" title="Edit section: Origins"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>During <a href="/wiki/World_War_I" title="World War I">World War I</a>, the German industrialist <a href="https://de.wikipedia.org/wiki/Reinhold_Becker_(Unternehmer)" class="extiw" title="de:Reinhold Becker (Unternehmer)">Reinhold Becker</a> developed a <a href="/wiki/20_mm_caliber" title="20 mm caliber">20 mm caliber</a> cannon, known now as the <a href="/wiki/20_mm_Becker" class="mw-redirect" title="20 mm Becker">20 mm Becker</a> using the <a href="/wiki/Blowback_(firearms)#Advanced_primer_ignition_(API)_blowback" title="Blowback (firearms)">advanced primer ignition blowback</a> (API blowback) method of operation. This used a 20×70mmRB cartridge and had a cyclic <a href="/wiki/Rate_of_fire" title="Rate of fire">rate of fire</a> of 300 rpm. It was used on a limited scale as an aircraft gun on <i><a href="/wiki/Luftstreitkr%C3%A4fte" title="Luftstreitkräfte">Luftstreitkräfte</a></i> warplanes, and an <a href="/wiki/Anti-aircraft_warfare" title="Anti-aircraft warfare">anti-aircraft</a> gun towards the end of that war. </p><p>Because the <a href="/wiki/Treaty_of_Versailles" title="Treaty of Versailles">Treaty of Versailles</a> banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm <a href="/wiki/SEMAG" class="mw-redirect" title="SEMAG">SEMAG</a> (<i>Seebach Maschinenbau Aktien Gesellschaft</i>) based near <a href="/wiki/Z%C3%BCrich" class="mw-redirect" title="Zürich">Zürich</a>. SEMAG continued development of the weapon, and in 1924 had produced the <i>SEMAG L</i>, a heavier weapon (43 kg) that fired more powerful 20×100mmRB ammunition at a slightly higher rate of fire, 350 rpm. </p><p>In 1924, SEMAG failed. The Oerlikon firm, named after the <a href="/wiki/Oerlikon_(Z%C3%BCrich)" title="Oerlikon (Zürich)">Zürich suburb of Oerlikon</a> where it was based, then acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. </p> <div class="mw-heading mw-heading4"><h4 id="Oerlikon">Oerlikon</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=4" title="Edit section: Oerlikon"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In 1927 the <i>Oerlikon S</i> was added to the existing product line. This fired a still larger cartridge (20x110RB) to achieve a muzzle velocity of 830 m/s (versus 490 m/s for the original Becker 20x70RB gun), at the cost of increased weight and a reduced rate of fire (280 rpm). The purpose of this development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon, which required a higher muzzle velocity. An improved version known as the 1S followed in 1930. </p><p>Three sizes of gun with their different ammunition and barrel length, but very similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the <i>AF</i> and <i>AL</i>, designed to be used in <a href="/wiki/Flexible_mount" class="mw-redirect" title="Flexible mount">flexible mounts</a>, i.e. manually aimed by a gunner. The 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds. </p><p>In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft. Designated with FF for <i>Flügelfest</i> meaning 'wing-mounted', these weapons were again available in the three sizes, with designations <i>FF</i>, <i>FFL</i> and <i>FFS</i>. The FF fired a slightly larger cartridge than the AF, 20x72RB, but the major improvement in these weapons was a significant increase in rate of fire. The FF weighed 24 kg and achieved a muzzle velocity of 550 to 600 m/s with a rate of fire of 520 rpm. The FFL of 30 kg fired a projectile at a muzzle velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high muzzle velocity of 830 m/s at a rate of 470 rpm.<sup id="cite_ref-FOOTNOTEWilliams2000_4-0" class="reference"><a href="#cite_note-FOOTNOTEWilliams2000-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Apart from changes to the design of the guns for wing-mounting and remote control, larger drums were introduced as it would not be possible to exchange magazines in flight. For the FF series 45, 60, 75 and 100 (and a rarely used 150) drum magazines were available, but most users chose the 30 or 60-round drum. </p><p>The 1930s were a period of global re-armament, and a number of foreign firms took licenses for the Oerlikon family of aircraft cannon. In France, <a href="/wiki/Hispano-Suiza" title="Hispano-Suiza">Hispano-Suiza</a> manufactured development of the FFS as the Hispano-Suiza HS.7 and Hispano-Suiza HS.9, for installation between the cylinder banks of its <a href="/wiki/V-12_engine" class="mw-redirect" title="V-12 engine">V-12 engines</a>. In Germany, <a href="/wiki/Ikaria" title="Ikaria">Ikaria</a> further developed the FF gun as the <a href="/wiki/MG_FF" class="mw-redirect" title="MG FF">MG FF</a>, firing 20x80RB ammunition. And the <a href="/wiki/Imperial_Japanese_Navy" title="Imperial Japanese Navy">Imperial Japanese Navy</a>, after evaluating all three guns, ordered developments of the FF and FFL as the <a href="/wiki/Type_99_cannon" title="Type 99 cannon">Type 99-1</a> and <a href="/wiki/Type_99_cannon" title="Type 99 cannon">Type 99-2</a>. </p><p>The incorporation of the improvements of the FFS in a new anti-aircraft gun produced, in 1938, the <i>Oerlikon SS</i>. Oerlikon realized further improvements in rate of fire on the 1SS of 1942, and the 2SS of 1945 which achieved 650 rpm. However, it was the original SS gun which was widely adopted as anti-aircraft gun, being especially widely used by <a href="/wiki/Allies_of_World_War_II" title="Allies of World War II">Allied</a> navies during <a href="/wiki/World_War_II" title="World War II">World War II</a>. </p><p>This gun used a 400-grain (26-gram) charge of <a href="/wiki/Improved_Military_Rifle_(IMR)" class="mw-redirect" title="Improved Military Rifle (IMR)">IMR 4831</a> <a href="/wiki/Smokeless_powder" title="Smokeless powder">smokeless powder</a> to propel a 2,000-grain (130-gram) projectile at 2,800 feet (850 meters) per second.<sup id="cite_ref-FOOTNOTEJohnson1944Appendix_5-0" class="reference"><a href="#cite_note-FOOTNOTEJohnson1944Appendix-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="World_War_II">World War II</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=5" title="Edit section: World War II"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:HMS_Dido_gun.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0a/HMS_Dido_gun.jpg/220px-HMS_Dido_gun.jpg" decoding="async" width="220" height="164" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0a/HMS_Dido_gun.jpg/330px-HMS_Dido_gun.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0a/HMS_Dido_gun.jpg/440px-HMS_Dido_gun.jpg 2x" data-file-width="800" data-file-height="596" /></a><figcaption>A <a href="/wiki/Royal_Navy" title="Royal Navy">Royal Navy</a> Oerlikon gunner at his gun mount aboard the <a href="/wiki/Dido-class_cruiser" title="Dido-class cruiser"><i>Dido</i>-class</a> <a href="/wiki/Cruiser" title="Cruiser">cruiser</a> <a href="/wiki/HMS_Dido_(37)" title="HMS Dido (37)">HMS <i>Dido</i></a> in 1942</figcaption></figure> <p>The Oerlikon FF was installed as armament on some fighters of the 1930s, such as the Polish <a href="/wiki/PZL_P.24" title="PZL P.24">PZL P.24</a>G. Locally produced derivatives of the Oerlikon cannon were used much more extensively, on aircraft, on ships and on land. In the air, the Ikaria <a href="/wiki/MG_FF" class="mw-redirect" title="MG FF">MG FF</a> was used as armament on a number of German aircraft, of which the most famous is the <a href="/wiki/Messerschmitt_Bf_109" title="Messerschmitt Bf 109">Messerschmitt Bf 109</a>. The Japanese Navy similarly used their copy of the FF, designated the <a href="/wiki/Type_99_cannon" title="Type 99 cannon">Type 99 Mark 1 cannon</a> on a number of types including the <a href="/wiki/Mitsubishi" title="Mitsubishi">Mitsubishi</a> <a href="/wiki/A6M_Zero" class="mw-redirect" title="A6M Zero">A6M Zero</a>. Later in the war, they also equipped fighters including the Zero with the <a href="/wiki/Type_99_cannon#Type_99_Mark_2" title="Type 99 cannon">Type 99 Mark 2</a>, a version of the more powerful and faster-firing Oerlikon FFL. </p><p>The French firm of Hispano-Suiza was a manufacturer of aircraft engines, and it marketed the <i>moteur-canon</i> combination of its <a href="/wiki/Hispano-Suiza_12X" title="Hispano-Suiza 12X">12X</a> and <a href="/wiki/Hispano-Suiza_12Y" title="Hispano-Suiza 12Y">12Y</a> engines with a <a href="/w/index.php?title=Hispano-Suiza_H.S.7&action=edit&redlink=1" class="new" title="Hispano-Suiza H.S.7 (page does not exist)">H.S.7</a> or <a href="/wiki/Hispano-Suiza_HS.9" class="mw-redirect" title="Hispano-Suiza HS.9">H.S.9</a> cannon installed between the cylinder banks. The gun fired through the hollow propeller hub, this being elevated above the crankcase by the design of the gearing. Such armament was installed on the <a href="/wiki/Morane-Saulnier_M.S.406" title="Morane-Saulnier M.S.406">Morane-Saulnier M.S.406</a> and some other types. Similar German installations of the MG FF were not successful. </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:British_20_mm_Oerlikon_shell_diagrams.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/British_20_mm_Oerlikon_shell_diagrams.jpg/220px-British_20_mm_Oerlikon_shell_diagrams.jpg" decoding="async" width="220" height="95" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/British_20_mm_Oerlikon_shell_diagrams.jpg/330px-British_20_mm_Oerlikon_shell_diagrams.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a5/British_20_mm_Oerlikon_shell_diagrams.jpg/440px-British_20_mm_Oerlikon_shell_diagrams.jpg 2x" data-file-width="1400" data-file-height="607" /></a><figcaption>Diagrams showing basic design and color-coding of British HE/incendiary, tracer and HE/incendiary/tracer shells for the 20 mm Oerlikon gun</figcaption></figure> <p>The Oerlikon became best known in its naval applications. Initially the Oerlikon was not looked upon favorably by the <a href="/wiki/Royal_Navy" title="Royal Navy">Royal Navy</a> as a short-range <a href="/wiki/Anti-aircraft" class="mw-redirect" title="Anti-aircraft">anti-aircraft</a> gun. In 1937–1938 Lord <a href="/wiki/Louis_Mountbatten" class="mw-redirect" title="Louis Mountbatten">Louis Mountbatten</a>, then a <a href="/wiki/Captain_(Royal_Navy)" title="Captain (Royal Navy)">captain</a> in the Royal Navy, advocated within the Royal Navy to set up an unprejudiced trial for the Oerlikon 20 mm gun, but was unsuccessful. It was not until the <a href="/wiki/Commander-in-Chief" class="mw-redirect" title="Commander-in-Chief">Commander-in-Chief</a> of the <a href="/wiki/Home_Fleet" title="Home Fleet">Home Fleet</a>, <a href="/wiki/Admiral" title="Admiral">Admiral</a> <a href="/wiki/Sir_Roger_Backhouse" class="mw-redirect" title="Sir Roger Backhouse">Sir Roger Backhouse</a>, was appointed <a href="/wiki/First_Sea_Lord" title="First Sea Lord">First Sea Lord</a> that Mountbatten's efforts bore fruit. During the first half of 1939 a contract for 1,500 guns was placed in Switzerland. However, due to delays and then later the <a href="/wiki/Battle_of_France" title="Battle of France">fall of France</a> in June 1940, only 109 guns reached the United Kingdom. All Oerlikon guns imported from Switzerland, in 1940, were mounted on various gun carriages to serve as light AA-guns on land. </p><p>Just a few weeks before the fall of France, the Oerlikon factory approved manufacture of their gun in the United Kingdom, under licence. The Royal Navy managed to smuggle out the necessary drawings and documents from <a href="/wiki/Z%C3%BCrich" class="mw-redirect" title="Zürich">Zürich</a>. The production of the first British-made Oerlikon guns started in <a href="/wiki/Ruislip" title="Ruislip">Ruislip</a>, <a href="/wiki/London" title="London">London</a>, at the end of 1940. The first guns were delivered to the Royal Navy in March or April, 1941. The <a href="/wiki/RAF_Regiment" title="RAF Regiment">RAF Regiment</a> made extensive use of Oerlikon guns in the anti-aircraft role. These were the principal armament for its light anti-aircraft squadrons in North Africa, the Middle East, Italy, and north western Europe, until the introduction of the <a href="/wiki/Bofors_40_mm_Automatic_Gun_L/60" class="mw-redirect" title="Bofors 40 mm Automatic Gun L/60">Bofors</a> 40/L60 40 mm gun from 1943, although many squadrons retained a mix of guns until the end of World War 2. Squadrons in the Far East were equipped exclusively with Oerlikons. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:CV-12_20mm_1945.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/CV-12_20mm_1945.jpg/220px-CV-12_20mm_1945.jpg" decoding="async" width="220" height="234" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/CV-12_20mm_1945.jpg/330px-CV-12_20mm_1945.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/32/CV-12_20mm_1945.jpg/440px-CV-12_20mm_1945.jpg 2x" data-file-width="2465" data-file-height="2617" /></a><figcaption>1945, a row of 20 mm Oerlikon guns aboard the <a href="/wiki/Essex-class_aircraft_carrier" title="Essex-class aircraft carrier"><i>Essex</i>-class</a> <a href="/wiki/Aircraft_carrier" title="Aircraft carrier">aircraft carrier</a> <a href="/wiki/USS_Hornet_(CV-12)" title="USS Hornet (CV-12)">USS <i>Hornet</i></a></figcaption></figure> <p>The Oerlikon gun was installed aboard <a href="/wiki/United_States_Navy" title="United States Navy">United States Navy</a> ships from 1942, replacing the <a href="/wiki/M2_Browning_machine_gun" class="mw-redirect" title="M2 Browning machine gun">M2 Browning machine gun</a>, which lacked range and firepower, and largely superseding the <a href="/wiki/1.1%22/75_caliber_gun" class="mw-redirect" title="1.1"/75 caliber gun">1.1"/75 caliber gun</a>, which was heavier and had less mechanical reliability. It became famous in the naval anti-aircraft role, providing an effective defense at short ranges (in practice up to 1.5 km) at which heavier guns had difficulty tracking a target. The gun was eventually abandoned as a major anti-air weapon due to its lack of <a href="/wiki/Stopping_power" title="Stopping power">stopping power</a> against heavy aircraft and against Japanese <i><a href="/wiki/Kamikaze" title="Kamikaze">kamikaze</a></i> attacks during the <a href="/wiki/Pacific_War" title="Pacific War">Pacific War</a>. It was largely superseded by the <a href="/wiki/Bofors_40_mm_Automatic_Gun_L/60" class="mw-redirect" title="Bofors 40 mm Automatic Gun L/60">Bofors 40 mm</a> gun and the <a href="/wiki/3%22/50_caliber_gun" class="mw-redirect" title="3"/50 caliber gun">3"/50 Mark 22 gun</a>. It provided a useful increase in firepower over the .50 cal machine gun when adapted and fitted to some aircraft. However, it had some problems with jamming in the ammunition feed. </p><p>The <a href="/wiki/Royal_Canadian_Navy" title="Royal Canadian Navy">Royal Canadian Navy</a> popularised the use of the Oerlikon gun as an anti-ship and anti-submarine gun – while it was not effective against the armour of most larger ships, it was used extensively and effectively against <a href="/wiki/U-boats" class="mw-redirect" title="U-boats">U-boats</a>, and on the decks of larger ships. A handful of <a href="/wiki/Corvette" title="Corvette">corvettes</a> were fitted with the weapon toward the end of the war, but it appeared more commonly on <a href="/wiki/Frigate" title="Frigate">frigates</a> and <a href="/wiki/Destroyer" title="Destroyer">destroyers</a> at the time. </p><p>The Oerlikon was also used as the basis for the <a href="/wiki/Polsten" class="mw-redirect" title="Polsten">Polsten</a> gun, designed by Polish engineers in exile in the United Kingdom. The gun went into service in 1944, and was used well into the 1950s, among other uses, on <a href="/wiki/Cromwell_tank" title="Cromwell tank">Cromwell tanks</a><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2015)">citation needed</span></a></i>]</sup> and early model <a href="/wiki/Centurion_tank" class="mw-redirect" title="Centurion tank">Centurion tanks</a>. </p><p>Romania purchased 45 pieces from Germany during the first half of World War II.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Post-war">Post-war</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=6" title="Edit section: Post-war"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Expand_section plainlinks metadata ambox mbox-small-left ambox-content" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Wiki_letter_w_cropped.svg" class="mw-file-description"><img alt="[icon]" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/20px-Wiki_letter_w_cropped.svg.png" decoding="async" width="20" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/30px-Wiki_letter_w_cropped.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/40px-Wiki_letter_w_cropped.svg.png 2x" data-file-width="44" data-file-height="31" /></a></span></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs expansion</b>. You can help by <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=">adding to it</a>. <span class="date-container"><i>(<span class="date">October 2011</span>)</i></span></div></td></tr></tbody></table> <p>It is still in use today on some naval units, nominally as a last-recourse anti-air weapon, but mainly used for firing <a href="/wiki/Warning_shot" title="Warning shot">warning shots</a> or incapacitating small vessels.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2021)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Description">Description</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=7" title="Edit section: Description"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg/220px-Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg/330px-Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg/440px-Oerlikon20_mm_cannon_on_the_SS_Jeremiah_O%27Brien.jpg 2x" data-file-width="2816" data-file-height="2112" /></a><figcaption>The aiming sight of the Oerlikon gun</figcaption></figure> <p>Unlike most high-powered autocannons, the Oerlikon and its derivatives have a <a href="/wiki/Blowback_(firearms)" title="Blowback (firearms)">blowback</a> mechanism: the bolt is not locked to the breech of the gun at the moment of firing. Non-locking, simple blowback designs are commonplace in much lighter weapons, such as small-caliber semi-automatic pistols. No locking is required, as with such low-power cartridges the static inertia of the bolt or bolt and slide - the physical tendency of heavy components to resist rapid acceleration - is adequate to ensure that the projectile has left the muzzle and the gas pressure in the barrel is down to a safe level before the breech opens (while the bolt spring also resists the opening of the breech, in practical terms its contribution is too small to be relevant).<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> In contrast, 20mm cartridges are far too powerful, and efficient autocannon barrels too long, for this basic system to be practical; so the Oerlikon uses <a href="/wiki/Advanced_Primer_Ignition" class="mw-redirect" title="Advanced Primer Ignition">Advanced Primer Ignition</a> (API) to augment the resistance of the bolt. In API blowback weapons, the firing pin fires the cartridge while the bolt is still traveling forward so that the gas pressure has to overcome the forward momentum of the bolt as well, before it can push it to the rear. To facilitate this, the Oerlikon's chamber is longer than needed to contain the cartridge, and the front-end of the bolt, which is the same diameter as the case, actually enters this extended chamber behind the cartridge before firing. As a result when firing occurs, the forward force of the bolt and spring acts against the force of the propellant gases until the latter overcome the former and start pushing case, bolt and spring backwards. If the bolt had stopped at the mouth of the chamber as in a simple blowback gun, this momentum would have been neutralized; instead thanks to the continuous movement the momentum acts to counter the propellant gases and slow the rearward travel of cartridge and bolt. Synergistically with this, a second advantage of this unusual arrangement is that after firing the bolt and case have a short, but significant, distance to travel rearwards before the bolt-end re-emerges and the case in turn begins to leave the chamber; and this in combination with the retardation of the rearward travel provides sufficient time for gas pressure to drop to the necessary safe level.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> This system permits blowback to be used in far more powerful weapons than normal. Nevertheless, compared to guns with a locking mechanism, a fairly heavy bolt must be employed; while to give this heavy bolt sufficient forward speed, a large spring is required (and Oerlikons, distinctively, have this component wrapped around their barrels.) These features will limit the rate of fire of such guns, unless other steps are taken—as in the final model of the <a href="/wiki/Type_99_cannon" title="Type 99 cannon">Japanese 99 Mark 2</a>.<sup id="cite_ref-FOOTNOTEWilliams2000_4-1" class="reference"><a href="#cite_note-FOOTNOTEWilliams2000-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png/170px-Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png" decoding="async" width="170" height="313" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png/255px-Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/51/Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png/340px-Difference_of_normal_and_rebated_rim_cartridge_in_blowback_operation.png 2x" data-file-width="435" data-file-height="800" /></a><figcaption>Difference of normal and rebated rim cartridge in blowback operation</figcaption></figure> <p>This unique chamber and bolt design necessitates the use of a characteristically shaped cartridge: the case has straight sides, very little neck, and a <a href="/wiki/Rebated_rim" class="mw-redirect" title="Rebated rim">rebated rim</a>. The straight sides allows the case to slide back and forward in the cylindrical chamber. The neck is not supported while this happens and therefore expands when the case is fired, and the rebated rim allows the face of the bolt, with its extractor claw hooked over the rim, to fit within the chamber. To ease the motion of the case, the ammunition needed to be greased, which was a drawback of the Oerlikon cannon. An alternative developed during World War II was the so-called fluted chamber, which had grooves that allowed propellant gas to seep between the chamber wall and the case, taking over the role of the grease.<sup id="cite_ref-FOOTNOTEWilliams2000_4-2" class="reference"><a href="#cite_note-FOOTNOTEWilliams2000-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <style data-mw-deduplicate="TemplateStyles:r1273380762/mw-parser-output/.tmulti">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .tmulti .multiimageinner span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent) img{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .tmulti .multiimageinner span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent) img{background-color:white}}</style><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:308px;max-width:308px"><div class="trow"><div class="tsingle" style="width:152px;max-width:152px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:HMCS_Haida_Hamilton_Ontario_13.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/HMCS_Haida_Hamilton_Ontario_13.jpg/150px-HMCS_Haida_Hamilton_Ontario_13.jpg" decoding="async" width="150" height="200" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/HMCS_Haida_Hamilton_Ontario_13.jpg/225px-HMCS_Haida_Hamilton_Ontario_13.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1e/HMCS_Haida_Hamilton_Ontario_13.jpg/300px-HMCS_Haida_Hamilton_Ontario_13.jpg 2x" data-file-width="2112" data-file-height="2816" /></a></span></div><div class="thumbcaption">Side view of the twin Oerlikon gun mount</div></div><div class="tsingle" style="width:152px;max-width:152px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:HMCS_Haida_Hamilton_Ontario_14.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9b/HMCS_Haida_Hamilton_Ontario_14.jpg/150px-HMCS_Haida_Hamilton_Ontario_14.jpg" decoding="async" width="150" height="200" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9b/HMCS_Haida_Hamilton_Ontario_14.jpg/225px-HMCS_Haida_Hamilton_Ontario_14.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9b/HMCS_Haida_Hamilton_Ontario_14.jpg/300px-HMCS_Haida_Hamilton_Ontario_14.jpg 2x" data-file-width="2112" data-file-height="2816" /></a></span></div><div class="thumbcaption">Rear view of the twin Oerlikon gun mount</div></div></div><div class="trow" style="display:flex"><div class="thumbcaption">A twin Oerlikon gun mount from the <a href="/wiki/Tribal-class_destroyer_(1936)" title="Tribal-class destroyer (1936)">Tribal-class destroyer</a> <a href="/wiki/HMCS_Haida" title="HMCS Haida">HMCS <i>Haida</i></a></div></div></div></div> <p>Ammunition feed is typically by a 60-round drum <a href="/wiki/Magazine_(firearms)" title="Magazine (firearms)">magazine</a> on the top of the gun. During sustained firing, the magazine must be frequently changed, reducing the effective rate of fire. Belt-fed versions of the gun were developed to overcome this limitation. A trigger in the right-hand grip controls fire. Used cartridges are ejected from below the breech. </p><p>Different nations and services operated a number of mounting types for the same basic gun. In a typical single-barrel naval version, it is free-swinging on a fixed <a href="/wiki/Pedestal" title="Pedestal">pedestal</a> mounting with a flat <a href="/wiki/Vehicle_armour" title="Vehicle armour">armored</a> shield affording some protection for the crew. The cannon is aimed and fired by a gunner using, in its simplest form, a ring-and-bead <a href="/wiki/Gunsight" class="mw-redirect" title="Gunsight">sight</a>. The gunner is attached to the weapon by a waist-belt and shoulder supports. For this reason, some mountings existed with a height-adjustment feature to compensate for different sized gunners. A "piece chief" designates targets and the feeder changes exhausted magazines. </p><p>During World War II, twin and quadruple Oerlikon mounts were developed, both for army and for navy use. The British Navy operated a hydraulically operated twin-gun mount. The US Navy operated a quad mount developed for <a href="/wiki/PT_boat" title="PT boat">PT boats</a> by Elco Naval Division, Electric Boat Company, called the Elco "Thunderbolt" mount. Prototypes were built and tested in late 1942 and operationally deployed on several Elco PT Boats in the Mediterranean.<sup id="cite_ref-Elco_Memo_9-0" class="reference"><a href="#cite_note-Elco_Memo-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Motor_Torpedo_Boat_Squadron_Twenty-Nine_Memo_10-0" class="reference"><a href="#cite_note-Motor_Torpedo_Boat_Squadron_Twenty-Nine_Memo-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> It was also placed experimentally on the battleships <a href="/wiki/USS_Arkansas_(BB-33)" title="USS Arkansas (BB-33)"><i>Arkansas</i></a>, <a href="/wiki/USS_Colorado_(BB-45)" title="USS Colorado (BB-45)"><i>Colorado</i></a>, <a href="/wiki/USS_Maryland_(BB-46)" title="USS Maryland (BB-46)"><i>Maryland</i></a>, <a href="/wiki/USS_West_Virginia_(BB-48)" title="USS West Virginia (BB-48)"><i>West Virginia</i></a>, <a href="/wiki/USS_Washington_(BB-56)" title="USS Washington (BB-56)"><i>Washington</i></a>, <a href="/wiki/USS_Massachusetts_(BB-59)" title="USS Massachusetts (BB-59)"><i>Massachusetts</i></a>, and training ship <a href="/wiki/USS_Wyoming_(BB-32)" title="USS Wyoming (BB-32)"><i>Wyoming</i></a>. </p> <div class="mw-heading mw-heading3"><h3 id="Variants">Variants</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=8" title="Edit section: Variants"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <table class="wikitable" style="text-align:center"> <tbody><tr> <th>Type</th> <th>F</th> <th>L</th> <th>S<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></th> <th>FFF</th> <th>FFL</th> <th>FFS </th></tr> <tr> <th>Caliber </th> <td colspan="6">20 mm </td></tr> <tr> <th>Action </th> <td colspan="6">API blowback </td></tr> <tr> <th>Weight [kg] </th> <td>30</td> <td>43</td> <td>62</td> <td>24</td> <td>30</td> <td>39 </td></tr> <tr> <th>Length [mm] </th> <td>1,350</td> <td>1,820</td> <td>2,120</td> <td>1,350</td> <td>1,880</td> <td>2,120 </td></tr> <tr> <th>Barrel length [mm] </th> <td>800</td> <td>1,200</td> <td>1,400</td> <td>760</td> <td>1,200</td> <td>1,400 </td></tr> <tr> <th>Rate of Fire [rpm] </th> <td>450</td> <td>350</td> <td>280</td> <td>520</td> <td>500</td> <td>470 </td></tr> <tr> <th>Muzzle velocity [m/s] </th> <td>550- 575</td> <td>670- 700</td> <td>835- 870</td> <td>550- 600</td> <td>675- 750</td> <td>830 </td></tr> <tr> <th>Cartridge type </th> <td>20x 70RB</td> <td>20x 101RB</td> <td>20x 110RB</td> <td>20x 72RB</td> <td>20x 101RB</td> <td>20x 110RB </td></tr> <tr> <th>Shell weight </th> <td colspan="6">127g </td></tr> <tr> <th>Feed system </th> <td colspan="3">Box magazine 15 rounds</td> <td colspan="3">Drums of 30, 45, 60, 75, 100 rounds or box magazine of 15 rounds </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Gas-operated_models">Gas-operated models</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=9" title="Edit section: Gas-operated models"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-Expand_section plainlinks metadata ambox mbox-small-left ambox-content" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Wiki_letter_w_cropped.svg" class="mw-file-description"><img alt="[icon]" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/20px-Wiki_letter_w_cropped.svg.png" decoding="async" width="20" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/30px-Wiki_letter_w_cropped.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/40px-Wiki_letter_w_cropped.svg.png 2x" data-file-width="44" data-file-height="31" /></a></span></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs expansion</b>. You can help by <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=">adding to it</a>. <span class="date-container"><i>(<span class="date">November 2022</span>)</i></span></div></td></tr></tbody></table> <p>Although guns with blowback action had played an important part in WW2, it was obvious that something better was needed, especially for the universal demand for a high rate of fire.<sup id="cite_ref-FOOTNOTEChinn1951b547–553_12-0" class="reference"><a href="#cite_note-FOOTNOTEChinn1951b547–553-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> The blowback mechanism requires a careful balance between the force of the shell being fired and the operational timing of the mechanism. In the Oerlikon designs, these timing demands resulted in a relatively slow-cycling weapon. </p><p>As a response to this demand, Oerlikon developed "power reserve loading" action,<sup id="cite_ref-FOOTNOTEChinn1951b547–553_12-1" class="reference"><a href="#cite_note-FOOTNOTEChinn1951b547–553-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> introducing a gas-operated mechanism to unlock the breech.<sup id="cite_ref-FOOTNOTEChinn1951b554–561_13-0" class="reference"><a href="#cite_note-FOOTNOTEChinn1951b554–561-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> The gun produced to this design after the close of hostilities of WW2, and was called the 5TG,<sup id="cite_ref-FOOTNOTEChinn1951b547–553_12-2" class="reference"><a href="#cite_note-FOOTNOTEChinn1951b547–553-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> and shortly thereafter, the <b>KAB</b>.<sup id="cite_ref-FOOTNOTEChinn1987257–262_14-0" class="reference"><a href="#cite_note-FOOTNOTEChinn1987257–262-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> It was the first Oerlikon gun design that differed radically from the original Becker design.<sup id="cite_ref-FOOTNOTEChinn1951b554–561_13-1" class="reference"><a href="#cite_note-FOOTNOTEChinn1951b554–561-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>Shortly after the War, Oerlikon began development of another gas-operated autocannon, 204-Gk, presently <b>KAA</b>.<sup id="cite_ref-FOOTNOTEChinn1987257–262_14-1" class="reference"><a href="#cite_note-FOOTNOTEChinn1987257–262-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Both 5TG (KAB) and 204-Gk (KAA) uses 20mm×128 ammunition cartridge being developed by Oerlikon in 1943.<sup id="cite_ref-FOOTNOTEChinn1987257–262_14-2" class="reference"><a href="#cite_note-FOOTNOTEChinn1987257–262-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-traditional"> <li class="gallerybox" style="width: 235px"> <div class="thumb" style="width: 230px; height: 180px;"><span typeof="mw:File"><a href="/wiki/File:20mm_gun.jpg" class="mw-file-description" title="GAM-B01, shipboard mount with single KAA"><img alt="GAM-B01, shipboard mount with single KAA" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/20mm_gun.jpg/200px-20mm_gun.jpg" decoding="async" width="200" height="135" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/20mm_gun.jpg/300px-20mm_gun.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/20mm_gun.jpg/400px-20mm_gun.jpg 2x" data-file-width="1428" data-file-height="963" /></a></span></div> <div class="gallerytext">GAM-B01, shipboard mount with single KAA</div> </li> <li class="gallerybox" style="width: 235px"> <div class="thumb" style="width: 230px; height: 180px;"><span typeof="mw:File"><a href="/wiki/File:C6C37B221.jpg" class="mw-file-description" title="GAI-B01 with single KAA mounted on a M113"><img alt="GAI-B01 with single KAA mounted on a M113" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/36/C6C37B221.jpg/122px-C6C37B221.jpg" decoding="async" width="122" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/36/C6C37B221.jpg/183px-C6C37B221.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/36/C6C37B221.jpg/245px-C6C37B221.jpg 2x" data-file-width="539" data-file-height="661" /></a></span></div> <div class="gallerytext"><a href="/wiki/Oerlikon_GAI-BO1" title="Oerlikon GAI-BO1">GAI-B01</a> with single KAA mounted on a <a href="/wiki/M113" class="mw-redirect" title="M113">M113</a></div> </li> <li class="gallerybox" style="width: 235px"> <div class="thumb" style="width: 230px; height: 180px;"><span typeof="mw:File"><a href="/wiki/File:Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG" class="mw-file-description" title="High-angle gun mount with single KAB"><img alt="High-angle gun mount with single KAB" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG/200px-Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG" decoding="async" width="200" height="132" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG/300px-Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG/400px-Ca%C3%B1%C3%B3n_Oerlikon_20-120_modelo_5_TG_2.JPG 2x" data-file-width="4928" data-file-height="3264" /></a></span></div> <div class="gallerytext">High-angle gun mount with single KAB</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=10" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/List_of_autocannon" title="List of autocannon">List of autocannon</a></li> <li><a href="/wiki/List_of_API_blowback_firearms" title="List of API blowback firearms">List of API blowback firearms</a></li> <li><a href="/wiki/20mm_caliber" class="mw-redirect" title="20mm caliber">20mm caliber</a></li> <li><a href="/wiki/2_cm_Flak_30/38/Flakvierling" class="mw-redirect" title="2 cm Flak 30/38/Flakvierling">2 cm Flak 30/38/Flakvierling</a></li> <li><a href="/wiki/20_mm_mod%C3%A8le_F2_gun" title="20 mm modèle F2 gun">20 mm modèle F2 gun</a></li> <li><a href="/wiki/25_mm_Hotchkiss_anti-aircraft_gun" title="25 mm Hotchkiss anti-aircraft gun">25 mm Hotchkiss anti-aircraft gun</a></li> <li><a href="/wiki/Hispano-Suiza_HS.404" title="Hispano-Suiza HS.404">Hispano-Suiza HS.404</a></li> <li><a href="/wiki/Type_96_25_mm_AT/AA_Gun" class="mw-redirect" title="Type 96 25 mm AT/AA Gun">Type 96 25 mm AT/AA gun</a></li> <li><a href="/wiki/Type_99_cannon" title="Type 99 cannon">Type 99 cannon</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=11" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFBudge2014" class="citation web cs1">Budge, Kent G. (2014). <a rel="nofollow" class="external text" href="http://pwencycl.kgbudge.com/2/0/20mm_Oerlikon_AA_gun.htm">"20mm Oerlikon Light Antiaircraft Gun"</a>. <i>The Pacific War Online Encyclopedia</i><span class="reference-accessdate">. Retrieved <span class="nowrap">30 May</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Pacific+War+Online+Encyclopedia&rft.atitle=20mm+Oerlikon+Light+Antiaircraft+Gun&rft.date=2014&rft.aulast=Budge&rft.aufirst=Kent+G.&rft_id=http%3A%2F%2Fpwencycl.kgbudge.com%2F2%2F0%2F20mm_Oerlikon_AA_gun.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></span> </li> <li id="cite_note-NAVWEAP1-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-NAVWEAP1_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.navweaps.com/Weapons/WNUS_2cm-70_mk234.htm">"Switzerland Oerlikon 20 mm/70 (0.79") Mark 1"<span class="cs1-kern-right"></span>"</a>. <i>NavWeaps.com</i>. 14 January 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">24 September</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=NavWeaps.com&rft.atitle=Switzerland+Oerlikon+20+mm%2F70+%280.79%22%29+Mark+1%22&rft.date=2011-01-14&rft_id=http%3A%2F%2Fwww.navweaps.com%2FWeapons%2FWNUS_2cm-70_mk234.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></span> </li> <li id="cite_note-NAVWEAP2-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-NAVWEAP2_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.navweaps.com/Weapons/WNBR_2cm-85_GAM.htm">"Britain 20 mm/85 (0.79") GAM-BO1"</a>. <i>NavWeaps.com</i>. 21 June 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">23 October</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=NavWeaps.com&rft.atitle=Britain+20+mm%2F85+%280.79%22%29+GAM-BO1&rft.date=2008-06-21&rft_id=http%3A%2F%2Fwww.navweaps.com%2FWeapons%2FWNBR_2cm-85_GAM.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></span> </li> <li id="cite_note-FOOTNOTEWilliams2000-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEWilliams2000_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEWilliams2000_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FOOTNOTEWilliams2000_4-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFWilliams2000">Williams (2000)</a>.</span> </li> <li id="cite_note-FOOTNOTEJohnson1944Appendix-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEJohnson1944Appendix_5-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFJohnson1944">Johnson (1944)</a>, Appendix.</span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAxworthy1995" class="citation book cs1">Axworthy, Mark (1995). <i>Third Axis, Fourth Ally: Romanian Armed Forces in the European War, 1941–1945</i>. London, UK: <a href="/wiki/Arms_and_Armour_Press" class="mw-redirect" title="Arms and Armour Press">Arms and Armour Press</a>. p. 30. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-85409-267-0" title="Special:BookSources/978-1-85409-267-0"><bdi>978-1-85409-267-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Third+Axis%2C+Fourth+Ally%3A+Romanian+Armed+Forces+in+the+European+War%2C+1941%E2%80%931945&rft.place=London%2C+UK&rft.pages=30&rft.pub=Arms+and+Armour+Press&rft.date=1995&rft.isbn=978-1-85409-267-0&rft.aulast=Axworthy&rft.aufirst=Mark&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">"The Machine Gun", Volume4, George M.Chinn., pages 12 and 15</span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text">"The Machine Gun", Volume4, George M.Chinn., page 13</span> </li> <li id="cite_note-Elco_Memo-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Elco_Memo_9-0">^</a></b></span> <span class="reference-text">Elco Naval Division Memo. <i>General Information on Elco Thunderbolt Mount, Mark II</i>, Bayonne, NJ: 1 December 1942.</span> </li> <li id="cite_note-Motor_Torpedo_Boat_Squadron_Twenty-Nine_Memo-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-Motor_Torpedo_Boat_Squadron_Twenty-Nine_Memo_10-0">^</a></b></span> <span class="reference-text">Motor Torpedo Boat Squadron Twenty-Nine Memo to CNO. <i>The Electric Boat Company Thunderbolt Quadruple 20 MM Powered Mount installed on PTs, operational report on</i>, New York, NY: 19 February 1945.</span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.airwar.ru/weapon/guns/oerlikon.html">"Oerlikon F/L/S (FFF/FFL/FFS) 20-мм автоматическая пушка"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Oerlikon+F%2FL%2FS+%28FFF%2FFFL%2FFFS%29+20-%D0%BC%D0%BC+%D0%B0%D0%B2%D1%82%D0%BE%D0%BC%D0%B0%D1%82%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B0%D1%8F+%D0%BF%D1%83%D1%88%D0%BA%D0%B0&rft_id=http%3A%2F%2Fwww.airwar.ru%2Fweapon%2Fguns%2Foerlikon.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></span> </li> <li id="cite_note-FOOTNOTEChinn1951b547–553-12"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEChinn1951b547–553_12-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEChinn1951b547–553_12-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FOOTNOTEChinn1951b547–553_12-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFChinn1951b">Chinn 1951b</a>, pp. 547–553.</span> </li> <li id="cite_note-FOOTNOTEChinn1951b554–561-13"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEChinn1951b554–561_13-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEChinn1951b554–561_13-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFChinn1951b">Chinn 1951b</a>, pp. 554–561.</span> </li> <li id="cite_note-FOOTNOTEChinn1987257–262-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEChinn1987257–262_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEChinn1987257–262_14-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FOOTNOTEChinn1987257–262_14-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFChinn1987">Chinn 1987</a>, pp. 257–262.</span> </li> </ol></div></div> <div class="mw-heading mw-heading3"><h3 id="Bibliography">Bibliography</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=12" title="Edit section: Bibliography"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCampbell1985" class="citation book cs1">Campbell, N. J. M. (1985). <i>Naval Weapons of World War Two</i>. <a href="/wiki/Annapolis" class="mw-redirect" title="Annapolis">Annapolis</a>: <a href="/wiki/Naval_Institute_Press" class="mw-redirect" title="Naval Institute Press">Naval Institute Press</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-87021-459-2" title="Special:BookSources/978-0-87021-459-2"><bdi>978-0-87021-459-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Naval+Weapons+of+World+War+Two&rft.place=Annapolis&rft.pub=Naval+Institute+Press&rft.date=1985&rft.isbn=978-0-87021-459-2&rft.aulast=Campbell&rft.aufirst=N.+J.+M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChinn1951" class="citation cs2"><a href="/wiki/George_M._Chinn" title="George M. Chinn">Chinn, George M.</a> (1951), <a rel="nofollow" class="external text" href="http://www.ibiblio.org/hyperwar/USN/ref/MG/I/index.html"><i>The Machine Gun: History Evolution and Development of Manual, Automatic, and Airborne Repeating Weapons</i></a>, vol. I, <a href="/wiki/Bureau_of_Ordnance" title="Bureau of Ordnance">Bureau of Ordnance</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Machine+Gun%3A+History+Evolution+and+Development+of+Manual%2C+Automatic%2C+and+Airborne+Repeating+Weapons&rft.pub=Bureau+of+Ordnance&rft.date=1951&rft.aulast=Chinn&rft.aufirst=George+M.&rft_id=http%3A%2F%2Fwww.ibiblio.org%2Fhyperwar%2FUSN%2Fref%2FMG%2FI%2Findex.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChinn1951b" class="citation cs2">Chinn, George M. (1951b), <a rel="nofollow" class="external text" href="https://archive.org/details/TheMachineGunVolume3ByGeorgeMChinn/page/n1/mode/2up"><i>The Machine Gun: Development During World War II and Korean Conflict by the United States and their Allies, of Full Automatic Machine Gun Systems and High Rate of Fire Power Driven Cannon</i></a>, vol. III, Bureau of Ordnance</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Machine+Gun%3A+Development+During+World+War+II+and+Korean+Conflict+by+the+United+States+and+their+Allies%2C+of+Full+Automatic+Machine+Gun+Systems+and+High+Rate+of+Fire+Power+Driven+Cannon&rft.pub=Bureau+of+Ordnance&rft.date=1951&rft.aulast=Chinn&rft.aufirst=George+M.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2FTheMachineGunVolume3ByGeorgeMChinn%2Fpage%2Fn1%2Fmode%2F2up&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChinn1987" class="citation cs2">Chinn, George M. (1987), <a rel="nofollow" class="external text" href="https://archive.org/details/TheMachineGunVolume5ByGeorgeMChinn"><i>The Machine Gun: Development of Full Automatic Machine Gun Systems, High Rate of Fire Power Driven Cannon, and Automatic Grenade Launchers by the United States and her Allies, following World War II, Korean Police Action, and the Vietnam Conflict</i></a>, vol. V, Bureau of Ordnance</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Machine+Gun%3A+Development+of+Full+Automatic+Machine+Gun+Systems%2C+High+Rate+of+Fire+Power+Driven+Cannon%2C+and+Automatic+Grenade+Launchers+by+the+United+States+and+her+Allies%2C+following+World+War+II%2C+Korean+Police+Action%2C+and+the+Vietnam+Conflict&rft.pub=Bureau+of+Ordnance&rft.date=1987&rft.aulast=Chinn&rft.aufirst=George+M.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2FTheMachineGunVolume5ByGeorgeMChinn&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFriedman2006" class="citation book cs1">Friedman, Norman (2006). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=4S3h8j_NEmkC&q=Oerlikon+20+mm%2F85+KAA&pg=PA478"><i>The Naval Institute Guide to World Naval Weapon Systems</i></a>. Annapolis: Naval Institute Press. pp. <span class="nowrap">478–</span>480. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-55750-262-9" title="Special:BookSources/978-1-55750-262-9"><bdi>978-1-55750-262-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Naval+Institute+Guide+to+World+Naval+Weapon+Systems&rft.place=Annapolis&rft.pages=%3Cspan+class%3D%22nowrap%22%3E478-%3C%2Fspan%3E480&rft.pub=Naval+Institute+Press&rft.date=2006&rft.isbn=978-1-55750-262-9&rft.aulast=Friedman&rft.aufirst=Norman&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D4S3h8j_NEmkC%26q%3DOerlikon%2B20%2Bmm%252F85%2BKAA%26pg%3DPA478&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHeller2002" class="citation book cs1 cs1-prop-foreign-lang-source">Heller, Daniel (2002). <i>Zwischen Unternehmertum, Politik und Überleben. Emil G. Bührle und die Werkzeugmaschinenfabrik Oerlikon, Bührle & Co 1924–1945</i> [<i>Between Entrepreneurship, Politics and Survival: Emil G. Bührle and the Oerlikon, Bührle & Co. Machine Tool Factory 1924-1945</i>] (in German). <a href="/wiki/Frauenfeld" title="Frauenfeld">Frauenfeld</a>, Switzerland: Verlag Huber. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3-71931-277-0" title="Special:BookSources/978-3-71931-277-0"><bdi>978-3-71931-277-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Zwischen+Unternehmertum%2C+Politik+und+%C3%9Cberleben.+Emil+G.+B%C3%BChrle+und+die+Werkzeugmaschinenfabrik+Oerlikon%2C+B%C3%BChrle+%26+Co+1924%E2%80%931945&rft.place=Frauenfeld%2C+Switzerland&rft.pub=Verlag+Huber&rft.date=2002&rft.isbn=978-3-71931-277-0&rft.aulast=Heller&rft.aufirst=Daniel&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJohnson1944" class="citation book cs1">Johnson, Melvin M. Jr. (1944). <i>Rifles and Machine Guns : A Modern Handbook of Infantry and Aircraft Arms</i>. New York: <a href="/wiki/William_Morrow_and_Co." class="mw-redirect" title="William Morrow and Co.">William Morrow and Co.</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Rifles+and+Machine+Guns+%3A+A+Modern+Handbook+of+Infantry+and+Aircraft+Arms&rft.place=New+York&rft.pub=William+Morrow+and+Co.&rft.date=1944&rft.aulast=Johnson&rft.aufirst=Melvin+M.+Jr.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPawle1978" class="citation book cs1">Pawle, Gerald (1978). <i>Secret Weapons of World War II</i>. New York: <a href="/wiki/Ballantine_Books" title="Ballantine Books">Ballantine Books</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-345-27895-X" title="Special:BookSources/0-345-27895-X"><bdi>0-345-27895-X</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Secret+Weapons+of+World+War+II&rft.place=New+York&rft.pub=Ballantine+Books&rft.date=1978&rft.isbn=0-345-27895-X&rft.aulast=Pawle&rft.aufirst=Gerald&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliams2000" class="citation book cs1">Williams, Anthony G. (2000). <i>Rapid Fire: The Development of Automatic Cannon, Heavy Machine-Guns and Their Ammunition for Armies, Navies and Air Forces</i>. <a href="/wiki/Shrewsbury" title="Shrewsbury">Shrewsbury</a>, UK: Airlife. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-84037-122-2" title="Special:BookSources/978-1-84037-122-2"><bdi>978-1-84037-122-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Rapid+Fire%3A+The+Development+of+Automatic+Cannon%2C+Heavy+Machine-Guns+and+Their+Ammunition+for+Armies%2C+Navies+and+Air+Forces&rft.place=Shrewsbury%2C+UK&rft.pub=Airlife&rft.date=2000&rft.isbn=978-1-84037-122-2&rft.aulast=Williams&rft.aufirst=Anthony+G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation journal cs1"><a rel="nofollow" class="external text" href="http://content.wisconsinhistory.org/cdm/ref/collection/ihc/id/16234">"Navy Day"</a>. <i>The Harvester World</i>. <b>35</b> (12). Chicago: Harvester Press: 12. December 1944.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Harvester+World&rft.atitle=Navy+Day&rft.volume=35&rft.issue=12&rft.pages=12&rft.date=1944-12&rft_id=http%3A%2F%2Fcontent.wisconsinhistory.org%2Fcdm%2Fref%2Fcollection%2Fihc%2Fid%2F16234&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Oerlikon_20_mm_cannon&action=edit&section=13" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <a href="https://commons.wikimedia.org/wiki/Oerlikon_20mm" class="extiw" title="commons:Oerlikon 20mm"><span style="font-style:italic; font-weight:bold;">Oerlikon 20mm</span></a>.</div></div> </div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliams2013" class="citation web cs1">Williams, Anthony G. (July 2013). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141110002552/http://www.quarryhs.co.uk/apib.html">"Of Oerlikons and Other Things……"</a>. <i>Military Guns & Ammunition</i>. Archived from <a rel="nofollow" class="external text" href="http://www.quarryhs.co.uk/apib.html">the original</a> on 10 November 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">16 September</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Military+Guns+%26+Ammunition&rft.atitle=Of+Oerlikons+and+Other+Things%E2%80%A6%E2%80%A6&rft.date=2013-07&rft.aulast=Williams&rft.aufirst=Anthony+G.&rft_id=http%3A%2F%2Fwww.quarryhs.co.uk%2Fapib.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.navsource.org/archives/01/015706l.jpg">"Naval Quad mount"</a>. <i>Navsource.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Navsource.org&rft.atitle=Naval+Quad+mount&rft_id=http%3A%2F%2Fwww.navsource.org%2Farchives%2F01%2F015706l.jpg&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFZlámal2009" class="citation web cs1 cs1-prop-foreign-lang-source">Zlámal, Stanislav (12 May 2009). <a rel="nofollow" class="external text" href="http://www.fronta.cz/dotaz/2cm-vkpl-vz-36-oerlikon">"2cm VKPL vz. 36 Oerlikon"</a>. <i>Fronta.cz</i> (in Czech).</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Fronta.cz&rft.atitle=2cm+VKPL+vz.+36+Oerlikon&rft.date=2009-05-12&rft.aulast=Zl%C3%A1mal&rft.aufirst=Stanislav&rft_id=http%3A%2F%2Fwww.fronta.cz%2Fdotaz%2F2cm-vkpl-vz-36-oerlikon&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWorld_of_Warships2017" class="citation web cs1">World of Warships (24 August 2017). <a rel="nofollow" class="external text" href="https://ghostarchive.org/varchive/youtube/20211030/W7qExnBNWJk">"Naval Legends: Oerlikon"</a>. <i><a href="/wiki/YouTube" title="YouTube">YouTube</a></i>. Archived from <a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=W7qExnBNWJk">the original</a> on 30 October 2021.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=YouTube&rft.atitle=Naval+Legends%3A+Oerlikon&rft.date=2017-08-24&rft.au=World+of+Warships&rft_id=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DW7qExnBNWJk&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOerlikon+20+mm+cannon" class="Z3988"></span></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl 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class="mw-redirect" title="British Commonwealth">British Commonwealth</a> naval weapons of the <a href="/wiki/World_War_II" title="World War II">Second World War</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Category:World_War_II_monitors_of_the_United_Kingdom" title="Category:World War II monitors of the United Kingdom">Monitor</a> guns</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BL_15-inch_Mk_I_naval_gun" title="BL 15-inch Mk I naval gun">BL 15-inch</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Capital_ship" title="Capital ship">Capital ship</a> main armament</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BL_14-inch_Mk_VII_naval_gun" title="BL 14-inch Mk VII naval gun">BL 14-inch</a></li> <li><a href="/wiki/BL_15-inch_Mk_I_naval_gun" title="BL 15-inch Mk I naval gun">BL 15-inch</a></li> <li><a href="/wiki/BL_16-inch_Mk_I_naval_gun" title="BL 16-inch Mk I naval gun">BL 16-inch</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Heavy_cruiser" title="Heavy cruiser">Heavy cruiser</a> main armament</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BL_7.5-inch_Mk_VI_naval_gun" title="BL 7.5-inch Mk VI naval gun">BL 7.5-inch Mk VI</a></li> <li><a href="/wiki/BL_8-inch_Mk_VIII_naval_gun" title="BL 8-inch Mk VIII naval gun">BL 8-inch Mk VIII</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Secondary armament and<br /><a href="/wiki/Light_cruiser" title="Light cruiser">light cruiser</a> main armament</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/QF_4-inch_naval_gun_Mk_V" title="QF 4-inch naval gun Mk V">QF 4-inch Mk V</a></li> <li><a href="/wiki/QF_4.5-inch_Mk_I_%E2%80%93_V_naval_gun" title="QF 4.5-inch Mk I – V naval gun">QF 4.5-inch</a></li> <li><a href="/wiki/QF_5.25-inch_naval_gun" title="QF 5.25-inch naval gun">QF 5.25-inch</a></li> <li><a href="/wiki/BL_5.5-inch_Mk_I_naval_gun" title="BL 5.5-inch Mk I naval gun">BL 5.5-inch</a></li> <li><a href="/wiki/BL_6-inch_Mk_XII_naval_gun" title="BL 6-inch Mk XII naval gun">BL 6-inch Mk XII</a></li> <li><a href="/wiki/BL_6-inch_Mk_XXII_naval_gun" title="BL 6-inch Mk XXII naval gun">BL 6-inch Mk XXII</a></li> <li><a href="/wiki/BL_6-inch_Mk_XXIII_naval_gun" title="BL 6-inch Mk XXIII naval gun">BL 6-inch Mk XXIII</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Category:World_War_II_minesweepers_of_the_United_Kingdom" title="Category:World War II minesweepers of the United Kingdom">Minesweeper</a>, <a href="/wiki/Category:World_War_II_sloops_of_the_United_Kingdom" title="Category:World War II sloops of the United Kingdom">Sloop</a>, <a href="/wiki/Category:World_War_II_corvettes_of_the_United_Kingdom" title="Category:World War II corvettes of the United Kingdom">Corvette</a>,<br /><a href="/wiki/Category:World_War_II_frigates_of_the_United_Kingdom" title="Category:World War II frigates of the United Kingdom">Frigate</a> and <a href="/wiki/Category:World_War_II_destroyers_of_the_United_Kingdom" title="Category:World War II destroyers of the United Kingdom">Destroyer</a> armament</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/QF_6-pounder_10_cwt_gun" title="QF 6-pounder 10 cwt gun">QF 6-pounder 10 cwt</a></li> <li><a href="/wiki/QF_12-pounder_12_cwt_naval_gun" title="QF 12-pounder 12 cwt naval gun">QF 12-pounder 12 cwt Mk V</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_IV,_XII,_XXII" title="QF 4-inch naval gun Mk IV, XII, XXII">QF 4-inch Mk IV</a></li> <li><a href="/wiki/BL_4-inch_Mk_IX_naval_gun" title="BL 4-inch Mk IX naval gun">BL 4-inch Mk IX</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_XVI" title="QF 4-inch naval gun Mk XVI">QF 4-inch Mk XVI</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_XIX" title="QF 4-inch naval gun Mk XIX">QF 4-inch Mk XIX</a></li> <li><a href="/wiki/QF_4.5-inch_Mk_I_%E2%80%93_V_naval_gun" title="QF 4.5-inch Mk I – V naval gun">QF 4.5-inch</a></li> <li><a href="/wiki/BL_4.7-inch_45-calibre_naval_gun" title="BL 4.7-inch 45-calibre naval gun">BL 4.7-inch Mk II</a></li> <li><a href="/wiki/QF_4.7-inch_Mk_IX_%26_XII_naval_gun" title="QF 4.7-inch Mk IX & XII naval gun">QF 4.7-inch Mk IX & XII</a></li> <li><a href="/wiki/QF_4.7-inch_Mk_XI_naval_gun" title="QF 4.7-inch Mk XI naval gun">QF 4.7-inch Mk XI</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Category:World_War_II_submarines_of_the_United_Kingdom" title="Category:World War II submarines of the United Kingdom">Submarine</a> guns</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/QF_12-pounder_12_cwt_naval_gun" title="QF 12-pounder 12 cwt naval gun">QF 12-pounder 12 cwt Mk V</a></li> <li><a href="/wiki/QF_3-inch_20_cwt" title="QF 3-inch 20 cwt">QF 3-inch 20 cwt</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_IV,_XII,_XXII" title="QF 4-inch naval gun Mk IV, XII, XXII">QF 4-inch Mk XII & XXII</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Anti-aircraft_warfare" title="Anti-aircraft warfare">Anti-aircraft weapons</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Unrotated_projectile" class="mw-redirect" title="Unrotated projectile">Unrotated projectile</a></li> <li><a href="/wiki/Holman_Projector" title="Holman Projector">Holman Projector</a></li> <li><a class="mw-selflink selflink">20 mm Oerlikon</a></li> <li><a href="/wiki/QF_2-pounder_naval_gun" title="QF 2-pounder naval gun">QF 2-pounder "pom-pom" Mk VIII</a></li> <li><a href="/wiki/Bofors_40_mm_Automatic_Gun_L/60" class="mw-redirect" title="Bofors 40 mm Automatic Gun L/60">40 mm Bofors</a></li> <li><a href="/wiki/QF_3-inch_20_cwt" title="QF 3-inch 20 cwt">QF 3-inch 20 cwt</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_V" title="QF 4-inch naval gun Mk V">QF 4-inch Mk V</a></li> <li><a href="/wiki/QF_4-inch_naval_gun_Mk_XVI" title="QF 4-inch naval gun Mk XVI">QF 4-inch Mk XVI</a></li> <li><a href="/wiki/QF_4.5-inch_Mk_I_%E2%80%93_V_naval_gun" title="QF 4.5-inch Mk I – V naval gun">QF 4.5-inch</a></li> <li><a href="/wiki/QF_4.7-inch_Mk_VIII_naval_gun" title="QF 4.7-inch Mk VIII naval gun">QF 4.7-inch Mk VIII</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Light weapons</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lewis_gun" title="Lewis gun">.303 Lewis machine gun</a></li> <li><a href="/wiki/Vickers_.50_machine_gun" title="Vickers .50 machine gun">.50 Vickers Mk III machine gun</a></li> <li><a href="/wiki/QF_3-pounder_Vickers" title="QF 3-pounder Vickers">QF 3-pounder Vickers</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;"><a href="/wiki/Torpedo" title="Torpedo">Torpedoes</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/British_21-inch_torpedo#21-inch_Mark_VII" title="British 21-inch torpedo">21-inch Mk VII</a></li> <li><a href="/wiki/British_21-inch_torpedo#21-inch_Mark_VIII" title="British 21-inch torpedo">21-inch Mk VIII</a></li> <li><a href="/wiki/British_21-inch_torpedo#21-inch_Mark_X" title="British 21-inch torpedo">21-inch Mk X</a></li> <li><a href="/wiki/British_21-inch_torpedo#21-inch_Mark_XI" title="British 21-inch torpedo">21-inch Mk XI</a></li> <li><a href="/wiki/British_24.5-inch_torpedo" title="British 24.5-inch torpedo">24.5-inch Mk I</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Anti-submarine weapons</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>Thornycroft <a href="/wiki/Depth_charge_thrower" class="mw-redirect" title="Depth charge thrower">depth charge thrower</a></li> <li><a href="/wiki/Hedgehog_(weapon)" title="Hedgehog (weapon)">Hedgehog</a></li> <li><a href="/wiki/Squid_(weapon)" title="Squid (weapon)">Squid</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Small craft armament</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ordnance_QF_6-pounder#Molins_gun" title="Ordnance QF 6-pounder">Molins 6-pounder</a></li> <li><a href="/wiki/Vickers_K_machine_gun" title="Vickers K machine gun">Vickers K machine gun</a></li> <li><a href="/wiki/British_18-inch_torpedo" title="British 18-inch torpedo">18-inch torpedo</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Foreign-sourced weapons</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a class="mw-selflink selflink">20 mm Oerlikon</a></li> <li><a href="/wiki/Bofors_40_mm_Automatic_Gun_L/60" class="mw-redirect" title="Bofors 40 mm Automatic Gun L/60">40 mm Bofors</a></li> <li><a href="/wiki/3%22/23_caliber_gun" class="mw-redirect" title="3"/23 caliber gun">3-inch 23 caliber gun (US)</a></li> <li><a href="/wiki/3%22/50_caliber_gun" class="mw-redirect" title="3"/50 caliber gun">3-inch 50 caliber gun (US)</a></li> <li><a href="/wiki/4%22/50_caliber_gun" class="mw-redirect" title="4"/50 caliber gun">4-inch 50 caliber Mark 9 gun (US)</a></li> <li><a href="/wiki/5%22/51_caliber_gun" class="mw-redirect" title="5"/51 caliber gun">5-inch 51 caliber Mark 8 gun (US)</a></li> <li><a href="/wiki/Y-gun" class="mw-redirect" title="Y-gun">Y-gun</a> depth charge projector (US)</li> <li><a href="/wiki/Bliss%E2%80%93Leavitt_Mark_8_torpedo" title="Bliss–Leavitt Mark 8 torpedo">Mark 8 torpedo (US)</a></li></ul> </div></td></tr></tbody></table></div> <p class="mw-empty-elt"> </p>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Oerlikon_20_mm_cannon&oldid=1270165692">https://en.wikipedia.org/w/index.php?title=Oerlikon_20_mm_cannon&oldid=1270165692</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:API_blowback_firearms" title="Category:API blowback 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