BLUF: Don’t dry fire your M240 machine gun because it can crack or break the receiver.
I’ve seen numerous M240 series machine guns with cracked or broken bolt guide rails in the receiver housing. It may be happening because the weapons were dry fired. Dry firing is when you release the bolt with no round chambered in the weapon.
Cracked receiver bolt guide rail
It’s not a good idea to dry fire any weapon, but dry firing the M240 can take it out of the fight, permanently.
Under normal operation, the locking bar will pivot before contacting the guide rails because of resistance against the bolt when the rounds cycle. When the weapon is dry fired, the locking bar is allowed to strike the guide rails with full force before it can pivot safely downward into the locking position.
When clearing or performing a function check on your M240 machine gun, always
ease the bolt forward. See the instructions in TM 9-1005-313-10 (May 22) for the correct way to let the bolt go forward without a round chambered.
Gerald W Knipe
Camp Humphreys, Korea
Editor’s note: Excellent point, Gerald! Thanks for the insights
Soldiers, take the time to ease the bolt forward and eliminate the potential for your M240 to develop cracks in the receiver.