The MG FF is a German 20mm autocannon used widely during the early stages of World War II. It was designed to be mounted in the wings of fighter planes, such as the Messerschmitt Bf 109E, being one of the first 20mm guns to be small and light enough for this purpose. The MG FF used a blowback mechanism and fired 20x80mm rounds from a drum magazine, which was limited to 60 or 90 shots. It had a rate of fire of about 520 rounds per minute and a muzzle velocity of 600 m/s. This autocannon was effective against lightly armoured targets but had limited range, accuracy and magazine size, also prone to jamming and overheating. The MG FF was introduced in 1937 and saw combat in the Spanish Civil War and the early stages of World War II, later being replaced by the more powerful and reliable MG 151/20/20 cannon, which used a different 20x82mm round.