Replacing Mount Base Rifle Ma

a. General. The mount base of this rifle is alined and leveled with respect to the bore line of the rifle to which it is assembled at manufacture, and should not be removed except for repair. If necessary to replace base on account of wear in the front mount ring mounting recess, or other damage, the new base must be leveled with respect to the bore line of the rifle. Lateral alinement of the base is fixed by the position of the screw holes in base and receiver for each barrel and receiver assembly. Leveling of the base with respect to the bore line is attained by raising the front or rear end of the base. Metal shims A153174 A, B, C, and D ranging in thickness from 0.005 plus or minus 0.001 inch to 0.020 plus or minus 0.001 inch are provided for this purpose. These shims are inserted between mount base and receiver, at front or rear end, to level the base.

b. Leveling Mount Base. To level the mount base, proceed as follows;

(1) Assemble mount base to receiver without shims, unless proper shim and its position is known. Turn mount base screws down, but not tightly.

(2) Adjust sight to zero windage and 100 yards elevation as described in TM 9-270, and mount sight to mount base.

(3) Bore sight rifle for windage as prescribed in paragraph 54r and note position of horizontal cross hair with respect to mark sighted on. If horizontal cross hair is above the mark the rear end of the base must be raised. If below the mark, the front end of base must be raised.

(4) Loosen both mount base screws slightly and insert a shim (thinuest first) between mount base and receiver at front or rear end as may be necessary, and tighten screws. Then check position of horizontal cross hair. (Be sure position of rifle is not shifted while inserting shim.) Continue with leveling until proper shim is found; then remove base and assemble shim, and screw base down tightly

(5) Check alinement and leveling on the range, and when correct stake mount base screws in position.

NOTE: To prevent rusting, oil receiver, mount base, and shim where they contact, before final assembly, using OIL, lubricating, preservative, medium.

58. ADJUSTING MOUNT RINGS ON TELESCOPIC SIGHT.

a. General. The front and rear mount rings of the Telescopic Sight M73B1 (Weaver No, 330 C) are adjusted and clamped to the sight when issued, and should not be removed except for repair. If these rings should become loose or detached while the sight is dismounted from the rifle, they can be assembled to the sight as explained in subparagraph b, below. The proper position of the mount rings with respect to the tube, and the proper position of the assembled sight with respect to the mount base are shown in figures S and 5.

Ik Assembly and Adjustment of Mount Rings.

(1) Loosen the mount ring screw and slide the narrow, rear mount ring onto the sight tube from the front end and back against the adjustment plate on the rear end of the tube. Turn the ring until the flat face of the lug is on the opposite side of the tube from the elevation screw marked "UP." Then tighten the mount ring screw sufficiently to hold in position, NOTE, step (4), below.

(2) Slide the board, front mount ring onto the sight tube in a similar manner until the front face of the ring is approximately 3Vi inches from the front end of the sight tube and the flat face of the mounting lug is parallel with the flat face of the lug on the rear mount ring; then, insert the lug on the front mount ring into the undercut recess in the mount base and turn the sight as in mounting (par. 8 d). As the rear mount ring approaches the mount base, move the sight backward or forward in the front mount ring until the rear ring will seat squarely in position on the mount base. Thread in and tighten the right lateral adjusting screw to hold the rear mount ring in position, and then partially tighten the two mount ring screws in the front mount ring Be sure the edges of the cupped heads of the lateral adjusting screws fit squarely in the radial notches in the lug on the rear mount ring and mount base before tightening the front mount ring screws.

CAUTION: Tighten mount ring screws only enough to hold sight firmly in position. If screws are drawn down too tight, the sight tube may become bent, the sight thrown out of adjustment or the lenses cracked.

(3) Dismount and mount the sight to test position of rings. When properly mounted, the elevation screw (marked "UP") should be on top and the windage screw (marked aL") on the left side with respect to the rifle. When position of mount rings is found to be correct, tighten the mount ring screws, after checking cross hairs,

(4) Check the cross hairs to see that they are exactly vertical and horizontal in the tube when mounted and, if necessary to correct alinement, adjust sight with respect to the mount base by loosening mount ring screws and turning the tube in the rings as prescribed in paragraph 56, above,

NOTE: To facilitate sliding of mount rings on the sight tube or turning tube in rings, expand rings slightly by inserting blade of small screwdriver or other similar instrument in slit in ring. Mount ring screws should not be fully tightened until sight is mounted and checked for position of cross hairs. Observe above caution.

c. Removal of Mount Rings. The mount rings may be removed from the sight tube by loosening mount ring screws and sliding rings from tube in same general manner as when assembling.

59. CARE, CLEAN1-SG, AND LUBRICATION.

a. Rifles should be cleaned and oiled not later than the evening of the day on which they are fired, preferably immediately after cessation of firing, and should be inspected, cleaned and oiled daily for 3 days following cessation of firing.

b. The first step in cleaning is to remove the groups from the rifle as described in paragraph 7. This is sufficient for cleaning in the field (FM 23-10), but for a thorough cleaning of the rifle by trained ordnance personnel, the groups should be disassembled, as described in section II, so that each piece can be cleaned and oiled.

c. Care and Cleaning of Bore, Chamber, and Metal Parts. The bore should be thoroughly cleaned with CLEANER, rifle bore. This cleaner is a combination solvent and preservative issued for use by troops for cleaning small arms. When CLEANER, rifle bore, is not available, the bore should be cleaned with soap and hot water solution, SODA ASH and water solution (1 Vi spoonfuls per pint of water), hot water alone, or in the absence of these, cold water. To avoid possible injury to the rifling at the muzzle, rifle bores will be cleaned from the chamber end, the bolt being removed for this purpose,

(1) To use CLEANER, rifle bore, insert a clean patch, cut, in the slot in the cleaning rod and saturate it with cleaner. Push patch back and forth through bore several times, taking care that all points of the bore are cleaned from muzzle to chamber. Be sure the patch goes all the way through the bore before the direction is reversed. This will prevent the patch and rod from becoming stuck in the bore. While the bore is wet, a clean brush, if available, should be run all the way through and all the way back three or four times to remove any hardened particles in the bore. Remove the brush and run several patches saturated with cleaner, entirely through the bore, removing them from the muzzle end; then wipe the cleaning rod dry and, using dry clean patches, thoroughly swab the bore until it is perfectly dry. Clean chamber thoroughly in same general manner, using a patch wrapped around a stick if necessary. To use soap and hot water solution, SODA ASH and water solution, or water alone, follow the same procedure. Care should be taken to avoid wetting the wooden stock or guard. Examine the bore and chamber carefully for cleanliness. If they are not free from all residue repeat the cleaning process-

(2) Oil bore and chamber thoroughly, using the cleaning rod and clean cut patches saturated with OIL, lubricating, preservative, speciaL The bore and chamber must be wiped completely dry of oil before firing the rifle.

(3) Use clean dry CLOTH, wiping, for cleaning all parts of the rifle other than the bore and chamber; then wipe the parts with clean CLOTH, wiping, dampened with oil and well wrung out. At all atmospheric temperatures OIL, lubricating, preservative, special, is suitable for this purpose. Excessive oiling is a waste of oil and results in a collection of dirt which causes friction and wear. In weather below freezing, care should be taken to use oil very sparingly, after careful cleaning of all parts. For care of weapons in extremely cold weather, refer to paragraph 61.

(4) In active service, use OIL, lubricating, preservative, special, for daily amplication or as a rust-preventive for short periods where daily inspection i:s possib!e. The weapon will be thoroughly cleaned and reoiled every 5 days. For surf landing operations or where high humidity or salt water spray is present use OIL, lubricating, preservative, medium. To prepare the weapon for storage, refer to paragraph 64.

d. Care of the Rifle Slock. About once a month apply OIL, linseed, raw, with a CLOTH, wiping, to the wood. The surplus oil should be wiped off and the stock polished with a clean dry cloth or the palm of the hand. Care must be exercised not to allow the oil to get into the mechanism of the rifle as it will harden and prevent functioning. The stock and hand guard or barrel guard should be removed from the barrel and receiver for such oiling.

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