Specifications

TM 05539-IN

BARRELED RECEIVER - CONTINUED 0022 00

0022 00-2

INSPECTION - CONTINUED

2. Inspect the muzzle end of the barrel (1) for a serviceable crown (2). The lands and grooves should come to a sharp end

with no nicks or burrs. If required, re-crown using a 45-degree cut crowning tool.

a. Secure barrel (1) in padded vise.

b. Mount 45-degree cut crowning tool onto a .308 caliber mandrel.

c. Lubricate crowning tool with cutting fluid and fully insert mandrel until the crowning tool touches the muzzle.

NOTE

When crowning muzzle, a 360-degree cut must be accomplished. This is done in 180-degree incre-

ments, with each turn of the crowning tool.

d. Apply firm pressure with your thumb on back of crowning tool and, with the other free hand, rotate the crowning

tool 180 degrees clockwise. Reposition your hand and complete the remaining 180-degree cut; continue until

smooth.

NOTE

If muzzle break is removed, new shim washers must be installed.

e. (M40A5) Inspect the muzzle break (4) for looseness, cracks, and/or damage. Inspect bearing surfaces (3) for burrs.

Replace muzzle break as necessary.

M40-021

M40-086