NEWS | March 30, 2020

M240 Machine Gun: Not All Buffers Are the Same

1-503 Inf Reg qualifying M240
Photo by Gerhard Seuffert

The story on the top of Page 39 in PS 801 (Aug 19) pointed out that units are seeing cracks in the M240 gun’s channels where the buffer assembly and buttstock slide in.  Cracks mean the M240 must be replaced.
To prevent cracks in channels...check to see if the buffer housing stop is missing any finish.
Check buffer housing stop for missing finish
to prevent cracks in channels.

Well, that guidance needs some clarification. Only the M240B and M240L models have this problem. The M240 uses a different buffer. 
One of the main causes for M240B and M240L cracking is buffer failure, which lets the operating rod strike the back plate with full force.
You can help prevent the cracking by doing the check in Step 4b of WP 0020 in TM 9-1005-313-10 (Nov 02, w/Ch7, Aug 10). If more than 1/8 inch of the finish is missing from the buffer housing stop, the machine gun is NMC, and the hydraulic buffer assembly needs replacing.