Oerlikon FF

Oerlikon FF 20 mm cannon
Type 99 Mark 1 cannon (Japanese license-built Oerlikon FF)
Type	Autocannon
Place of origin	Switzerland
Service history
In service	1940–
Used by	Various
Wars	World War II
Production history
Designer	Reinhold Becker
Designed	1935
Manufacturer	Oerlikon
Variants	Type 99 Mark 1 cannon MG FF cannon
Specifications
Mass	25 kg (55 lb) [1]
Barrel length	L/38: 760 mm (30 in)[1]
Shell	20mm×72RB[1]
Caliber	20 mm (0.787inch)
Barrels	Single barrel (progressive RH parabolic twist, 9 grooves)
Action	API blowback
Rate of fire	520 rounds per minute[1]
Muzzle velocity	600 m/s (2,000 ft/s)[1]
Feed system	Cylindrical magazine holding 60 rounds, Later adjusted to be a belt fed gun

The FF were a series of 20mm autocannon introduced by Oerlikon in the late 1920s. The name comes from the German term Flügel Fest, meaning wing mounted, fixed, being one of the first 20mm guns to be small and light enough to fit into a fighter aircraft's wing. The FF series inspired many 20mm cannon used in World War II, including the Hispano-Suiza HS.404 (adopted by the French, British and U.S. forces), the German MG FF, and the Japanese IJNAS's Type 99 cannon.