Draft:20×102mm

The 20×102mm cartridge is a common type of 20 mm caliber ammunition developed for the United States Armed Forces during the Cold War and still widely used primarily in the light autocannons of many western militaries, being standardized for NATO usage as STANAG 3585 since 2008.

History
During the Second World War, Americans forces deployed overseas began to notice that various European 20 mm autocannons outpaced their smaller .50 in machine guns in firepower while also being significantly lighter. In suit, the USAAC began licensed production of an American adaptation of the 20mm Hispano-Suiza HS.404 aircraft gun (designated M1, T-31, later M24) based on British variants, which soon proved to be extremely unreliable despite bureaucratic efforts to force it into broad service.

After the war, with recently captured Nazi German technology newly available, the USAF decided to restart this endeavor from scratch inspired by the Mauser MG 213 20mm prototype revolver cannon. By the early 1950s, the result was a revolver-type aircraft gun designated the T-160, chambered in a new 20×102mm cartridge designed specifically for this weapon over the aging 20×110mm HS used previously.

The round was likely first used in combat sometime in early 1953 during the Korean War on one of 8 North American F-86 Sabres as part of "Project GunVal", in which their six .50 BMG M3 machine guns were replaced with four 20mm T-160 autocannons and redesignated F-86F-2 to test up-gunning aircrafts with insufficient firepower for aerial combat of the time.

The results of the experiment were a great success; not only did the T-160 go on to be adopted as Aircraft Gun Unit M39 for later models of F-86 among others such as the North American F-100 Super Sabre, but the data was influential in General Electric's "Project Vulcan", where the cartridge was simultaneously being tested since the prior year in a variant of the T-45 15 mm Gatling gun designated T-171, which led to its eventual standardization as the main armament of American warplanes.

Weapon platforms

 * M39 revolver cannon, used on the Northrop F-5
 * M61 Vulcan rotary cannon, used on the Republic F-105 Thunderchief, Phalanx CIWS, M163 VADS, among others
 * M197 electric rotary cannon, used on the North American Rockwell OV-10 Bronco
 * XM301 experimental rotary cannon, used on the Boeing–Sikorsky RAH-66 Comanche
 * M167 VADS anti-aircraft rotary cannon
 * Anzio 20mm anti-materiel rifle

Czechia

 * ZVI PL-20 Plamen electric Gast principle cannon, used on the Aero L-159 Alca

France

 * M621 cannon, used on the Aérospatiale SA 330 Puma, Nexter NaRWHAL 20A

Iran

 * Arash anti-materiel rifle