Technical data

TM 9-1005-319-23&P 0009
0009-4
TEST AND INSPECTION - Continued
5. Functionally inspect key and bolt carrier assembly and gas tube alignment. Refer to TM 9-1005-319-10
and use the following procedures:
a. Disengage the takedown pin and open the receiver.
b. Remove bolt carrier assembly.
c. Remove bolt assembly from bolt carrier assembly.
d. Insert key and bolt carrier assembly into upper receiver and barrel assembly. The bolt assembly
must not be installed while performing test.
e. Slide key and bolt carrier assembly forward to detect binding between key and bolt carrier
assembly and gas tube by feel. Badly bent gas tube could cause damage to both the key and bolt
carrier assembly and the gas tube. A slightly bent gas tube will cause unnecessary wear of the key
and bolt carrier assembly and gas tube.
f. Correct slight binding by removing handguard assemblies and slightly bending gas tube in the
handguard area while repeating step e above until no binding is detected. Badly bent gas tubes
will be replaced and realigned.
g. Remove key and bolt carrier assembly from upper receiver and barrel assembly.
h. Reassemble bolt assembly into key and bolt carrier assembly.
i. Reinstall key and bolt carrier assembly into upper receiver and barrel assembly.
M16A2 ONLY
6. Check rear sight assembly as follows:
a. Rotate elevation knob counterclockwise until the rear sight assembly is all the way down. If a
whole click is not felt as the rear sight assembly stops, the rear sight assembly has bottomed out
and will not pivot freely.
b. Position elevation knob back slightly to its last whole click as the rear sight assembly base is under
tension of the ball bearing and helical spring. The 300 meter mark should align with the mark on
the receiver.
c. If the 300 meter mark is not aligned with the mark on receiver, slip the range scale in the following
manner:
(1) Position the 300 meter mark with the mark on the receiver.
(2) Insert a 1/16 in. key wrench through the access hole of the rear sight assembly base and into
the index screw.
(3) Loosen the index screw three turns and leave the wrench in place.
(4) Rotate lower portion of elevation knob counterclockwise until it stops (range scale should not
have moved). Elevation knob should be positioned on its last whole click.