TM 9-1275

Function Firing And Final Inspection

38. Function Firing
Following complete rebuild, each weapon is function fired using three full clips of standard service ball ammunition. Guns which fail to meet the function firing test are corrected by such component replacement or repair as required. These guns are again subjected to a function firing test which must be met for acceptance of the rifle. The clips should be replaced occasionally as worn clips will not give a true functioning test. After function firing the weapons must be thoroughly cleaned in the prescribed manner to prevent corrosion.

39. Final Inspection
a. General. Weapons turned in for repair may be assumed to have defects caused by use or neglect. When they are accepted as new weapons, the parts composing them were dimensionally correct and made of the proper material. Consequently, the inspection of these weapons after repair will differ from the inspection procedure used in the manufacturing plant, in that attention will be directed to wearing surfaces, parts that might crack or break due to high stress or fatigue, and evidences of corrosion. These defects do not evidence themselves by uniform reduction in a given dimension but show up as a chipped edge, a partially worn surface, or an eccentric hole. A gage used in manufacturing is merely a means of comparing an unknown dimension with a known one to judge whether a piece comes within tolerances. After this piece is worn thorough use, the change in dimension is more easily detected in many cases by comparing with adjacent surfaces; the piece in itself becomes a gage. Visual inspection, therefore, is far more applicable in these cases and gaging is limited to those dimensions that are critical or that may be more advantageously measured than compared. Inspection of noncritical parts (parts that do not cause malfunctions) will be limited to appearance and the presence of cracks or flaws. The dimensions placed on these parts (and gaging used during manufacturing) were for the sole purpose of insuring interchangeability. Even if the dimensions of such parts are worn considerably below drawing tolerances, functioning and interchangeability will not be adversely affected and the parts are consequently acceptable.
b. Visual Inspection. As indicated in a above, visual inspection is primarily a comparison of a worn or chipped surface with the adjacent surface or the corresponding portion of a new part. Unserviceability is a matter of personal judgment and cannot be put down in definite measurements. Over-all appearance shall approximate that of a new weapon. All exposed surfaces are to have a dull, rust-resistant finish with no burs, deep scratches, or tool marks. Barrels must be straight, clean, free of rust and powder fouling, and free of bulges and rings. Fine pitting is allowable. Rifles must be complete with no missing parts. All applicable modifications must be applied. The serial number must be legible. All metal parts must be free of rust. Inspect visually for the following:

(1) General appearance, smoothness of operation, function of clip, latch, and follower. test with clip of dummy cartridges.
(2) Try cap of butt plate.
(3) Inspect stock and hand guards for cracks or mutilation.
(4) Be certain swivels and screws are staked properly.
(5) Inspect gas cylinder and lock for burs.
(6) Inspect front sight for looseness and bent or burred wings.
(7) Inspect rear sight for following:
(a) Binding of windage.
(b) Elevation, looseness, and sharpness of clicks.
(8) Inspect trigger housing group for the following:
(a) Bent trigger guard.
(b) Burs on lugs that lock trigger group to receiver.
(c) Worn locking notch on trigger guard.
(d) Tension of clip ejector.
(e) Function of safety, trigger, sear, and hammer.

c. Function And Inspection With Gages. (1) Operate by hand to ascertain that final adjustments have been made to assure proper operation.
(2) Check trigger pull. Refer to serviceability chart (fig. 23).
(3) When inspecting the bolt, gage the firing pin protrusion. The minimum should be 0.044 inch and the maximum should be 0.0590 inch. Note shape and condition of the firing pin point.
(4) Check for headspace. Refer to serviceability chart (fig. 23).
(5) Inspect the bore and chamber.
(6) Assemble and function test with dummy cartridges.
d. Marking. If passed, stamp with name of appropriate arsenal and inspector's initials.

 

TM 9-1275