M174E3 Grenade Launcher

The M174E3 is a mounted automatic 40mm grenade launcher heavily based on the M1919A4 machine gun and the M79 grenade launcher but fed from an ammo can. It was used in the Vietnam War (then designated the XM174) as a tripod mounted crew-served weapon and as a weapon mounted on various vehicles and aircraft.

The ammunition canister holds 12 40mm rounds, and the automatic launcher's rate of fire permits all 12 rounds to be in the air before the first round lands. The launcher is also capable of semi-automatic fire.

U.S. Air Force Security Police personnel in Vietnam were also issued the XM174 automatic grenade launcher which was often used on perimeter defense posts and heavy weapons vehicles.