Maintenance Instructions

10044S
Colt Canada Proprietary 4-1 2005-09-20
PART 4
TESTS AND ADJUSTMENTS
FIRING PIN PROTRUSION
1. Test firing pin protrusion as follows:
a. Disassemble the firing pin and bolt from the bolt carrier;
b. Thoroughly clean the firing pin, bolt and firing pin protrusion gauge;
c. Insert the firing pin into the bolt from the rear and hold it fully forward; and
d. Gauge firing pin protrusion. See Figure 4-1.
2. Should the firing pin protrusion not meet gauging limits, that is if it is not within the 0.71
to 0.91 mm (0.028 to 0.036 in.) range, ensure that carbon build-up or burring in the bolt are not
causing the problem. Determine the cause of the problem and replace defective parts as
required.
BORE EROSION
3. Bore wear is gauged by using the barrel
erosion gauge 8790190-1. To determine barrel
life proceed as follows:
a. Remove the bolt carrier group and
separate the upper and lower receivers;
b. Thoroughly clean the chamber, bore
and barrel erosion gauge;
c. With the barrel in the horizontal position
insert the gauge into the breech end
until it stops, DO NOT force; and
d. Determine barrel life by reading the
gauge marking that is in line with the
rear face of the upper receiver.
See Figure 4-2.
4. When erosion and wear of the barrel
result in the reject line of the gauge entering
the upper receiver, past the rear face, the
weapon shall be backloaded.
BORE STRAIGHTNESS
5. Test bore straightness by the following procedure:
Figure 4-1 Gauging Firing Pin Protrusion
Figure 4-2 Gauging the Barrel