Originally developed in 1923 as a gun for aircraft and called Model 1921, it was renamed the M2 in 1933. It was then decided that the mass of the barrel needed to be increased. Re-design also replaced the oil buffer which eliminated the need for oil. These modifications to the original model prolonged the life of the weapon and cut down on maintenance. Yet again, the name changed to the M2 HB (HB-Heavy barrel). It has remained unchanged since the last re-naming took place and is now used on the ground and on vehicles. Many are found mounted on Humvees and other military vehicles.

		Cartridge: 12.74X99mm (0.50 M2 Ball) Operation: short recoil Locking: projecting lug Feed: disintegrating link belt Weight: 38 kg Length: 1.651 m Barrel: 1.143 m Rifling: 8 grooves, rh, 1 turn in 381 mm Sights: fore, blade; rear, leaf aperture Muzzle velocity: 930 m/s Rate of fire: cyclic, 450-600 rds/min Max range: 6,800 m; effective, 1,500 m

		Ramo Manufacturing Inc.

Source(s): Jane's Infantry Weapons, 24th Edition 1998-99.