The Flieger Doppelpistole was a Swiss creation shortly after World War I for a light aircraft machine gun that could also be used as a submachine gun. The weapon featured two barrels which fired cyclically, creating a rate of firepower around 1,900 rounds per minute. Chambered in 7.65x21mm Parabellum, the submachine gun used a toggle delayed blowback which fired from an open bolt. While the Flieger-Doppelpistole could generate a high rate of fire, its 7.65x21mm cartridge was not up to the task of downing aircraft. In addition its high rate of fire quickly drained its double 40 round magazines. Few of these submachine guns were ever produced, most seeing ground use with the Swiss Army.