5. Inspect barrel for pits in bore, burrs, broken or worn locking lugs, and surface cracks and defects.
a. Pits no wider than a land or groove and 3/8 inch (0.953 cm) or less in length are allowable in the bore.
b. Uniformly fine pits in a densely pitted area of the bore are allowable.
c. Lands that appear dark due to coating of gliding metal from projectiles are allowable.
d. Striping of lands and grooves shall not be cause for rejection unless support maintenance determines by use of the barrel erosion gage.
e. For pits other than mentioned above, broken or burred locking lugs, or surface cracks, evacuate to support maintenance.
6. Inspect bore for ringing. Definitely ringed bores or bores ringed sufficiently to bulge the outside surfaces of the barrel are causes for rejection. Evacuate to support maintenance.
7. Inspect chamber for pitting. Fine pits, or fine pits in a densely pitted area, are allowable. Pits 1/8 inch (0.318 cm) in length are cause for rejection. Evacuate to support maintenance.
8. Hand check compensator (3) for looseness on barrel. The third (middle) slot (4) must be straight up at top dead center (TDC). The alignment may vary as much as one half the width of the slot either direction. If loose or out of alignment, evacuate to support maintenance.
9. Inspect all items for serviceability in and tightness of latch assembly on ejection port cover. If items are damaged or nonfunctional, they are unserviceable.
10. Rotate and test elevation index (5) and windage knob (6) for ease of functioning and legibility of markings.
11. Inspect elevation knob zero as follows:
a. Rotate elevation knob (7) 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 so the rear sight assembly base (8) is under tension of the ball bearing (9) and helical spring (10). 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 inch allen wrench through the access hole of the rear sight assembly base and into the Index screw (11).
(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.
(5) Tighten index screw and remove wrench.
(6) Check for proper setting.
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