GTA 09-06-045
31AUG07
M2 MG - HEADSPACE ADJUSTMENT
WARNING: Weapon may explode if not properly head spaced!
NOTE: Ensure charging handle is retracted before inserting barrel.
NOTE: Headspace and timing must be performed each time the barrel is installed
NOTE: Ensure barrel is a lined barrel (PN 7266131).
1. Raise cover all the way up, retract bolt to align barrel locking spring lug with 3/8” hole
in right side of receiver.
2. With bolt retracted, screw barrel completely into barrel extension; then unscrew barrel
two clicks. Allow bolt to go forward; barrel should not rotate.
3. Charge the weapon and allow the bolt to go forward. (Do not slam)
4. Retract the bolt until the barrel extension begins to separate (but not more than 1/16 inch)
from the trunnion block. (DO NOT INSERT ANY OBJECT BETWEEN THE BARREL
EXTENSION AND TRUNNION BLOCK). Hold in this position until gage check is completed.
5. Raise cartridge extractor; push in on alignment guide to insert gage. (Apply slight pressure
on gage). Attempt to insert “GO” end of headspace gage in the T-slot between the face of
bolt and rear of barrel all the way up to the ring. If “GO” end of headspace gage enters
down to the ring, attempt to insert the “NO GO” end of headspace gage; if “NO GO” end
does not enter, headspace is set. If “NO GO” end enters T-slot or “GO” end does not enter,
retract bolt to align barrel locking spring lug with 3/8” hole in right side of receiver.
6. Screw barrel in one click at a time (if “NO GO” end enters slot) or one click out at a time
(if “GO” end does not enter) rechecking after each click starting from Step 4 above.
7. Repeat until “GO” end can enter T-slot and “NO GO” will not enter T-slot.
CAUTION: Do not unscrew barrel more than a total of seven clicks.
If condition occurs, turn in machine gun for next echelon inspection.
