Becker Type M2 20 mm cannon The Becker Type M2 20 mm cannon was a German automatic cannon developed for aircraft use during World War I by " Stahlwerke Becker " . It was first mass - produced in 1916 and was installed in a variety of aircraft ; the only German autocannon to actually see service in the air during the war . The Becker also served as the pattern for the famous Oerlikon 20 mm cannon , which sees service to this day . History . Design & development . Development commenced in 1913 and was therefore already advanced when the War Ministry issued a specification in June 1915 calling for an aircraft cannon of under 37 mm caliber and 70 kg weight capable of firing a 10 - round burst . Tests commenced shortly thereafter with the weapon mounted in a Gotha G . I , but proved unsatisfactory . Despite this , the potential of the gun was such that the arsenal at Spandau was engaged to help develop and fine - tune the design , leading to a production contract for 120 Becker Type M2 guns in June 1916 . In addition to the orders for aircraft guns placed with Becker , Spandau and MAN also received a contract to build Becker cannon for the Army . The Spandau works developed the gun further producing it as the Spandau Type 3 20mm cannon , which was heavier and had a slower rate of fire at 250 rpm . Operational use . The main types to utilise the Type M2 were large aircraft - the Friedrichshafen G . III bomber and AEG G . IVk ground - attack machine . Tests in smaller , single - engined aircraft were not so successful , but were carried out extensively through the rest of the war , commencing with an Albatros J . I in December 1917 . Due to the gun ' s operating principles , it could not be synchronised , and this posed an immediate problem for its installation in this type of plane . The solution adopted after the tests with the Albatros J . I was to mount the gun at an angle to fire downwards . Fitting the gun to a fighter with a pusher configuration was another obvious solution , and trials were carried out with an Albatros D . VI . Other intended installations were for an AGO S . I and the Hansa ( Caspar ) D . I , but these were not carried out before the Armistice . Total production figures are not known , but were in excess of 539 ( 111 by Becker and 428 by MAN ) ; a total of 362 were surrendered to the Allies . Postwar use and patterns . The patent for the gun was bought by SEMAG ( " Seebach Maschinenbau Aktien Gesellschaft " ) in 1921 , who continued development with a more powerful cartridge as the SEMAG L . After the collapse of SEMAG Oerlikon took over the SEMAG assets in 1924 , marketing improved versions as the Oerlikon F , Oerlikon L and Oerlikon S . Description . The Type M2 was a slim weapon working on the principle of advanced primer ignition blowback . It weighed only 30 kg . It was fed by a somewhat awkward , curved box magazine , available in versions that held 10 or 15 rounds ; the latter weighed another 5 kg . As the rate of fire was 325 rounds per minute , this magazine could be emptied very quickly . The muzzle velocity was 490 m / s , which was low compared to the rifle - calibre machine guns of the period such as the German MG 08 , but a respectable performance compared to other automatic cannon of the period , such as the Vickers QF 1 pounder pom - pom . Competing German designs . During WWI , at least two other German 20 - mm autocannons were designed and saw limited production . One was the 2cm Ehrhardt , the other was the 19 - mm ( sometimes reported as 20 - mm ) Szakats .