Perform this procedure only if flat washers (16) and pan-head machine screws (15) are missing.
Install four flat washers (16) and pan-head machine screws (15).
DIRECT SUPPORT MAINTENANCE OF RECEIVER ASSEMBLY M240/M240C, NSN N/A, PN 11826192; M240B, NSN N/A, PN 12976834; M240D, NSN N/A, PN 12977104; M240E1, NSN N/A, PN 12597044; M240G, NSN N/A, PN 12997566; M240N, NSN N/A, PN 12976834 (cont)
Lubricate threads of all screws before installation.
(M240B): Install the accessory rail body (24) against the receiver at the receiver/gas tube juncture with the extruded end pointing forward on the gas tube.
Do not over-tighten screws, damage to gas tube can occur.
Install new lock washer (22) on each of the screws (26), apply loctite 246 (item 5, WP 0074 00) to the threads and insert into the forward and rear mounting holes from right to left. Hand tighten screw until finger tight. Using a 5/32" hex wrench, tighten the forward screw no more than 3 revolutions past finger tight. Tighten the rear screw no more than 1/4 revolution past finger tight.
Function check weapon, if the operating rod binds in the gas tube back-off the screws 1/4 turn. Continue to function check until the operating rod moves freely through the gas tube.
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