Figure Adjustable rear sight assembly for Ml MA and M carbines

a. Repair. As the adjustable rear sight is replaceable only as an assembly, no replacement spare parts are furnished for field repair. Check machined type sight for loose or missing index plate and screw. The sight should be kept clean and lightly oiled to prevent rusting and insure proper operation.

Carbine Sight Disassembly

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Carbine Rear Sight Disassembly

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b. Refinishing. To remove corrosion from the rear sight assembly without removing it from the barrel and receiver assembly, proceed as follows:

(1) Sand blast the adjustable rear sight assembly, when necessary, using fine grit and a controlled air pressure.

(2) Blow accumulated grit and dust from the assembly with compressed air having a moisture filter.

(3) Phosphate finish the assembly.

(4) After finishing, thoroughly rinse, dry, and oil the assembly with water displacing oil.

(5) Test rear sight ramp to determine that it traverses completely to left and right without binding.

(6) Test aperture and it must move freely up and down the ramp under normal finger pressure.

c. Cleaning. The sight is cleaned best with a small brush and clean cloths. Remove light rust with preservative lubricating oil. Use crocus cloth for removal of heavy rust, but since its use produces shine, exercise caution. When cleaning, move ramp and aperture slide in order to clean thoroughly under them.

d. Oiling. Immediately after cleaning, apply a light film of preservative lubricating oil to all exposed metal surfaces to prevent rusting. Excess oil will collect foreign matter, which will clog the sight and cause excessive wear. A small drop of oil on index balls and ramp guide plunger will lubricate and preserve these parts and their component springs. Such oiling is best done with the dropper of the oiler, or a broom straw dipped in oil. Wipe off excess oil.

Index Balls
Figure 69. Rear sight assembling tool with spacer.
Carbineimages
Figure 70. Moving rear sight in place with torque wrench.

Note. When cleaning the carbine, apply a small drop of oil to the aperture slide guideways in the ramp, the threads of the windage screw, the index balls, and ramp guide plunger. Use preservative lubricating oil (medium) above +32 degrees F. and in humid climates, and preservative lubricating oil (speical) below +32 degrees F.

e. Loose Sight Base. If the sight base becomes loose in the receiver, tighten it by restaking the receiver into either of the two notches in the dovetail base of the sight. If base has shifted, it should be realigned and restaked. If sight has been staked properly, it can be restaked in the same place. If necessary to restake at other than the previous points of staking, file new idents in sight base and stake receiver opposite the new indents. Make certain that points of staking are one-six-teenth of an inch from edges of dovetail slot and directly opposite the indents. If staking fixture does not line up with idents in sight base, perform staking free-handed as outlined above.

ASSEMBLY (FIELD MAINTENANCE)

a. Press new rear sight into right side of dovetail by hand.

b. Center the aperture ramp on the sight base.

c. If stamped type sight is being placed on receiver, place spacer attached to assembling tool

Peening Lug Ruger

Figure 71. Peening receiver to reduce oversize dovetail slot.

Figure 71. Peening receiver to reduce oversize dovetail slot.

Caution: Reading on torque wrench should be taken during movement of the wrench, as reading taken when starting the wrench will be high, due to starting torque in moving jack screw. Exercise great care during the procedure outlined in g above, as the dovetail base of the sight is hardened as well as the dovetail slot in the receiver. Because of this, it is necessary that the load limits as prescribed and as indicated on the torque wrench, be rigidly maintained. If too great a pressure is exerted in the placement of the sight, the receiver of the carbine will crack or break; and if too light a pressure is exerted, the sight will work loose under the shock of firing.

h. Continue operation above until zero line on sight base (machined type sight) or zero sight plate (stamped type sight) is aligned with scribe mark on rear of receiver.

L Remove the tool from the receiver. j. Screw ramp of sight to extreme left. k. Stake rear sight in place.

7312068 in place for reinforcing the side wings of sight (Fig. 69).

d. Place assembling tool on receiver with lip of assembling tool engaging operating slide guide-way in receiver.

e. Move assembling tool to rear until dovetail guide (sliding member) on tool will enter dovetail slot in receiver.

f. Tighten right jack screw by hand until block of jack screw is against the side of sight.

g. Insert torque wrench 41-W-3628-85, and move the sight into the dovetail slot (Fig. 70). Wrench should show an applied torque reading of between 18 and 54 inch-pounds. If the reading is not within the above limits, remove sight and proceed as follows:

(1) If reading is below 18 inch-pounds indent the area in front of the dovetail slot. This can first be done by using punch 7312234 (Fig. 73) and rapping punch with a hammer. Undertake this operation with extreme caution. A blow only hard enough to cause a flow of metal into the dovetail slot is necessary.

(2) If reading is above 54 inch-pounds, file the bottom of the sight base as shown in figure 72. Do not attempt to file the edges of the sight base and under no circumstances should the receiver be filed.

Note. The staking operation is extremely critical and success of this operation will depend largely upon the skill and judgment of the operation (Fig. 73). Bear in mind that the sharp upper edges of the dovetail slot on the receiver are easily chipped or cracked, and such damage will ultimately result in an unserviceable weapon. Many problems will arise which will have to be solved by the individual mechanic; a few of these problems and their remedies are listed in (1) and (2) below.

(1) Indents on sight base dovetail may be horizontally misaligned with references to holes in sight base. If the indents are slightly out of horizontal alignment they may be corrected by enlarging the indents very slightly with a small three-square file.

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Figure 72. Filing rear sight base to fit undersize dovetail slot.

Figure 72. Filing rear sight base to fit undersize dovetail slot.

(2) Sometimes sufficient material is not available on the receiver to permit an adequate staking job. This is particularly true when the sight is moved to one of its extreme positions. In this case, the procedure outlined in (1) above should be followed and new indents made to permit adequate staking.

/. On the machined type adjustable rear sight the index plate is held in place by a small screw. On some of these sights the screw is staked in such a manner as to prevent its removal. Take care, when zeroing the rifle by a movement of the index plate, to loosen the screw only enough to permit movement of the index plate.

m. The index plate on the stamped type sight is directly below the ramp and in the center rear portion of the sight base. Move this plate with a small drift to prevent damage to any of the components of the sight and weapon.

SECTION IX. BARREL AND RECEIVER GROUP

DISASSEMBLY

a. Removing Barrel From Receiver (DEPOT MAINTENANCE ONLY). Do not remove the barrel from the receiver except for replacement of a new barrel. Replace barrel if it is bent or damaged, if the chamber is worn to the extent of effecting excessive headspace or if it does not meet the requirements specified in table III. Completely disassemble all components from barrel and receiver. Place barrel in jaw protected vise. Allow enough of the rear end of the barrel to project from the vise to permit the wrench 7113308 to be positioned over front of receiver (Fig. 76). Place wrench over receiver near barrel and unscrew counterclockwise.

b. Removing Gas Piston and Piston Nut (FIELD OR DEPOT MAINTENANCE).

(1) The gas piston and piston nut are the only removable parts of the gas cylinder group. To .remove the piston, clamp the barrel firmly in a vise with protected jaws, and using gas piston nut removing tool M5 5621065 or gas cylinder reconditioning tool 7160995 (with wrench component), unscrew the piston nut counterclockwise from gas cylinder (Fig. 77). Take care not to bur or twist prongs on nut when removing (nut. is staked in place) or piston will not move freely. Remove nut, elevate muzzle of barrel, and slide piston out of gas cylinder. If necessary, tap cylinder lightly with a wooden block to slide piston out. If nut does not loosen readily, soak with preservative lubricating oil, special, for about an hour to loosen. Oil can be dropped through gas port drill hole in gas cylinder.

(2) If piston becomes "frozen" in the gas cylinder due to carbon or rust, soak with preservative lubricating oil (special) for about an hour and then work out of cylinder. When the nut and piston are removed, clean gas cylinder and piston thoroughly and oil lightly.

Carbine Gas Piston
Figure 73. Rear sight showing staking.

(3) The gas cylinder may be integral with the barrel, or swaged on the barrel at manufacture. Do not remove the gas cylinder. If gas cylinder is unserviceable, barrel assembly should be replaced (DEPOT MAINTENANCE ONLY).

INSPECTION

(1) Inspect operating slide spring well for rust or foreign matter. Visually inspect receiver for break-through of the operating slide spring hole. This breakthrough occurred in the original manufacture of some receivers because of the drill running out through either the bottom or right-hand exterior surfaces. If the forward end of the break-through is 3 inches or more from the front end of the receiver, it is acceptable; otherwise, it must be rejected (DEPOT MAINTENANCE ONLY). Any sharp or feather edges around this break-through are to be removed.

(2) Inspect receiver under "black light" (Magnaglo or approved equal) for cracks in the area around the bolt locking slot at the right hand side and at the front and rear trigger housing retaining lugs (DEPOT MAINTENANCE ONLY). Receivers having cracks extending in both directions around a corner must be rejected.

(3) Visually inspect condition of firing pin retracting cam mating cut in the bridge of receiver (Fig. 78). This cam was cut to an angle of 33 degrees in the earlier manufacture of receivers and later to 45 degrees. Both are acceptable if in good condition.

(4) Visually inspect trigger housing retaining pinhole in the receiver. If out of-roundness is apparent, reject the receiver (DEPOT MAINTENANCE ONLY).

(5) Inspect the bullet ramp in the receiver to assure it is clean and smooth for proper feeding of the ammunition. Burrs and sharp edges should be removed by careful polishing with fine emery cloth. The lower edge of the

How Linkless Feed System Works

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  • Kibra
    How do you move the rear aperature on the ramp of the sight on m1 carbine?
    8 years ago
  • Leah
    How does m1 oiler work?
    8 years ago

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