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NEWS | April 13, 2022

M2A1 Machine Gun: Confirm Your Weapon Was Gaged Prior to Firing

M2A1 machine gun
Photo courtesy of TACOM

Gunners, one of the biggest improvements of the M2A1 machine gun over the M2 machine gun is that you no longer need to headspace and time your weapon before firing. But you can’t forget about headspace and timing (HS&T) altogether.
The unit armorer must verify the HS&T of each M2A1 before it’s signed out of the unit’s arms room. The gunner needs to confirm the weapon was verified by the armorer before firing.
Don’t fire a weapon if you’re not sure the HS&T was verified. Firing a weapon with improper headspace and timing can cause malfunctions, damage the weapon or, potentially, injure you.
To help you understand the importance of headspace and timing, let’s define each one.
  • Headspace is the distance between the rear of the barrel and the face of the bolt.
  • Timing is the adjustment of the gun so that it fires when the recoiling parts are in the correct position. 
Now that you know what headspace and timing are, here’s what can cause the M2A1 to be out of tolerance. HS&T for an M2A1 is set by a weapon manufacturer, depot or field maintainer. When HS&T is set, it is the correct HS&T for that M2A1 in its current condition. As the weapon is fired, parts inside the M2A1 can wear and are no longer in the condition they were in when HS&T was set. To keep the weapon safely firing as parts wear, a wear limit was accounted for in the design of all M2A1s.
However, if an M2A1 is continually fired and HS&T isn’t verified when the M2A1 is drawn from the arms room, the wear can eventually exceed the wear limits. When this happens, the weapon must go in for maintenance to have the HS&T reset.
Continuing to fire a weapon that is out of HS&T is not only unsafe, but also results in additional, damaging wear to the bolt and breech lock, worsening the issue.
So, remember:

Armorers - Check your M2A1’s HS&T with the wear limit and timing gage, NSN 5220-01-580-6602, whenever the M2A1 is signed out of your arms room. M2A1s that fail gaging should have their HS&T reset and their bolt and breech locks inspected by a qualified field maintainer following guidance in the M2A1’s TM 9-1005-347-23&P (Jul 11).

Gunners – Before you take your weapon to the range, confirm your armorer has gaged your M2A1 when it’s issued. Your weapon will thank you for it.
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