The machine gun, caliber .30, M1919A4, is recoil operated, belt fed, and air cooled. In recoil operation the rearward force of the expanding powder gas (kick) furnishes the operating energy. The moving parts, while locked together at the moment of the explosion, are left free within the receiver to be forced to the rear by the recoil. This movement is controlled by means of various springs, cams, and levers, and is utilized to perform the necessary mechanical operations of unlocking the breech, extraction and ejection of the empty case, and feeding in of the new round, as well as cocking, locking, and firing the mechanism. (See fig. 1.) The receiver mechanism is for all practical purposes the receiver of the Browning machine gun, M1917.
DesignationFM 23-45
EditionJan 1940
StatusSuperseded
Pages35
FunctionMarksmanship Weapons
CollectionHistoric
Public domain (U.S. Government work)