Figure 84. Reaming chamber for head space.
and small patch. Be sure rear end of tube is clean.
c. Re finishing of Barrel and Receiver. When necessary to sand or grit blast to remove rust, or otherwise prepare the barrel and receiver for re-finishing, remove the rear sight and front band. If practicable, the front sight should be kept mated with the barrel and receiver assembly from which it is removed. When original finish is reasonably satisfactory, the removal of front and rear sights and the front band to permit sand blasting, in order to obtain the highest quality protective finish, is not required. During any refinishing of the barrel and receiver, the gas cylinder, muzzle, and breech end of the barrel must be plugged with corks to prevent solution from entering the bore or the cylinder portion of the gas cylinder. By drilling a 3/16-inch hole through the rear end of the receiver into the operating slide spring hole, good circulation of phosphating solutions and preservative compounds can be obtained.
d. Rearning Chamber.
(1) Dip breeching space reamer 7319906 in lard oil and place in chamber through top opening of receiver (Fig. 84). Turn ing handle slowly to the right, remove only sufficient metal to permit bolt to close on head space gage 7319934 (head space length 1.290 inches).
(2) Wash chips from reamer and chamber with lard oil after removing from chaml>er.
(3) Handle reamer with care to prevent it. from being chipped or picked. Never turn reamer backwards in chamber as this tends to dull the cutting edges.
e. Restoring Serial Numbers (FIELD MAINTENANCE). Serial numbers which have become obscured because of the installation of the adjustable rear sight must be restored. Since the degree of obscurity varies, this will be effected in one of two ways: (1) if the serial number is questionable (Fig. 85) (one digit obscured), use white graduation filler 52-F-l 00-230, listed in Department of the Army Supply Catalog ORD 3 SNLK-1, to improve the legibility; and (2) if the serial number is obscured (Fig. 85), it will be relocated on the receiver bridge directly forward of the rear sight platform (Fig. 86).
(1) Questionable serial numbers (FIELD MAINTENANCE ONL Y).
(а) Mask the adjustable rear sight to prevent filler from entering the sight.
(б) Work a small quantity of filler into the serial number and allow it to dry for 5 minutes. Wipe off all excess filler with a clean rag and allow to dry for 3 hours.
(c) In the event that the application of filler fails to restore the legibility of the serial number, relocation of
the number by depot maintenance personnel is required.
(2) Obscured serial numbers (DEPOT MAINTENANCE ONLY). Maintenance organizations engaged in restamping serial numbers will fabricate fixtures locally to reinforce and clamp the receiver during the stamping operation. Two fixtures have been developed for this purpose; the vise-held stamping fixture (Figs. 87 and 88) and the bench-mounted stamping fixture (Figs. 89 and 90). The choice of fixture which best suits the requirements of the maintenance organization is left to the discretion of that organization, (a) Vise-fie Id stamping fixture. This fixture is relatively simple to fabricate requires little space for storage, and may be quickly mounted in any vise. However, it is not adapt able at maintenance installations where large quantities of carbines are to be restamped, since the carbines must be disassembled before relocation of serial numbers can be accomplished.
(/>) Restamping with vise-held stamping fixture.
1. Secure fixture firmly in vise as shown in figures 87 and 88.
2. Clamp the barrel and receiver assembly in the fixture (Figs. 87 and 88).
Note. The fixture is so designed that disassembling the barrel and receiver assembly is not required.
3. Manually position and space the 3/32-inch stamping fixture on the bridge of the receiver directly forward of the rear sight platform (Fig. 86). Strike the stamping fixture with one firm blow of the hammer to insure a neat and distinct impression. Repeat this procedure until all digits of serial number are transposed.
Note. The 3/32-inch stamping fixture is not included in the supply system and must be procured locally.
Figure 89. Carbine clamped in bench-mounted stamping fixture.
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