Abstract: An ammunition feed mechanism for a machine gun includes a sprocket having rtridge feeding and positioning splines. This sprocket rotates in a feed direction to move a belt of linked cartridges into position for chambering and firing. An anti-backup pawl prevents counterrotation and maintains the sprocket in position while a cartridge is chambered. A ratchet release permits bidirectional rotation of the sprocket in loading and unloading of the ammunition belt. The rotation of the sprocket for feeding is done with a cam tube actuator making a ratchet connection with the sprocket. The reciprocating movement of the bolt carrier causes rotary movement of the actuator by means of a pin on the bolt carrier riding in the cam of the actuator. The bolt carrier has a depressible rammer for chambering the cartridges.

Abstract: A lightweight one man portable automatic gas-operated weapon system for intry use having symmetrical forces applied to recoiling parts by use of two parallel gas pressure actuated rods acting in unison. An integral sprocket feed system is actuated by the recoiling parts and avoids gross asymmetrical force movements about the weapon's center of gravity resulting from shifting ammunition weight. A dual tube receiver and dual gas system is featured in the weapon. Major weapon subassemblies comprising modules are operatively interrelated to facilitate replacement during field use of the weapon.