After 70 years of distinguished service, the U.S. Army is preparing to retire the M2HB .50-caliber machine guns. Replacing the M2 will be the lighter and more accurate XM312 .50 caliber (12.7 mm). The new weapon from General Dynamics, Falls Church, Va., is based on prototypes of the company’s XM307, a rapid-fire grenade launcher scheduled to see service in 2010. Changing only the barrel and five other parts converts the grenade launcher into a machine gun. But the Pentagon didn’t want soldiers to wait for a more accurate and stable weapon, so the Army is deploying XM312s two years from now.
The XM312 is a lightweight, low-recoil gun that mounts on vehicles and tripods and fires standard .50-caliber cartridges, including tracers, armor-piercing incendiaries, and sabot light-armor penatrators. Rounds feed from the left or right using the same deteriorating metal belt as the M2 uses.
The gun weighs just 43 lb, including tripod, much less than the Browning M2’s 128 lb, but still heavy enough to require a two-man team. Its peak firing rate is only 260 rounds/min, much less than the M2’s 600 rounds/min. The relatively slow rate of cyclic fire or peak firing rate makes the new weapon ineffective against fast-moving and airborne targets. But the XM312 should have a slightly higher practical rate of fire (the rate of fire a gun can sustain for an indefinite period without damage) than the M2’s 40 rounds/min. Range will also improve, going from the M2’s 1,500 to 2,000 m. A planned magnification and night-vision scope will let GIs take advantage of this longer range. EFL
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