Marine units have received an upgraded .50-caliber machine gun that aims to make firing quicker, safer and less visible to the enemy.

Marine Corps Systems Command officials in Quantico, Virginia, released information Thursday about the upgrades, which include a quick-change barrel, fixed headspace and timing, and a flash hider that reduces the machine gun's signature by 95 percent at night. 

"The improved M2A1 makes Marines more lethal because they're able to get rounds down range quicker," said Maj. Harry Thompson, team lead for General Purpose Weapons at the command.

The current machine gun requires Marines to manually set headspace and timing before firing and after the barrel heats from high fire volumes. 

Headspace is the distance between the face of the bolt and the base of the cartridge when chambered, while timing is the adjustment of the weapon so firing occurs when the recoiling parts are in the correct position. 

The quick-change barrel is now possible because the headspace and timing are now fixed, Thompson said.

The current version requires Marines to screw in the barrel and set the headspace, he said. Now the improved version allows Marines to "pop" the receiver and lock it in place similar to the M240B machine gun.

The combination reduces the time Marines are exposed to enemy fire and shortens the time the weapon is out of operation for barrel changes, he said.

The third improvement is a flash hider at the end of the barrel that reduces muzzle flash to mask Marines' position and limits whiteout conditions, helping the use of night vision while firing, Thompson said.

In total, the command will field 3,600 M2A1s to Marines, said Kelly Sullivan, a General Purpose Weapons program analyst. Phase one concluded in March and included infantry and most infantry-like units and infantry reserves. Phase two will run through May. The Army began its upgrades to the .50-caliber machine gun in 2011.