| 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.