The FMK is an Argentine blowback operated sub-machine-gun first introduced in the 1970s. The FMK is chambered for the 9 mm Parabellum cartridge which it takes from a 25-round magazine and fires in single shots or fully automatic at a rate of 650 rounds per minute. The FMK is the standard issue sub-machine-gun with the Argentine forces and saw actio... Found on http://www.probertencyclopaedia.com/browse/FMF.HTM