1. SCOPE. - a. This technical bulletin is published for the information and guidance of those concerned pending the publication of FM 23-7 and TM 9-1276.
     b. In addition to a description of the Carbine, Cal. .30, Ml, this technical bulletin contains information required for the identification, use and care of the materiel and its component accessories, including available information on ammunition.
     c. Disassembly, assembly, and such repairs as may be handled using arms personnel will be undertaken only under the supervision of an officer or the chief mechanic.
     d. In all cases where the nature of the repair, modification or adjustment is beyond the scope or facilities of the unit, the responsible ordnance service should be informed in order that trained personnel with suitable tools and equipment may be provided, or proper instructions issued.

    2. DESCRIPTION. - a. The Carbine, Cal. .30, M1 (Figures 1, 2 and 3) is a gas-operated, self-loading, air-cooled, shoulder weapon, delivering semi-automatic fire controlled by the operator. It is fed by a box magazine containing 15 cartridges staggered in the magazine. The weapon has an over-all length of approximately 36 inches and weighs approximately 5.80 pounds with sling and loaded magazine attached.
     b. The carbine is in many ways similar in operation, functioning, and general design to the U. S. Rifle, Cal. .30, Ml, and, in general, is composed of four main groups of assemblies and ports: the barrel and receiver, the trigger mechanism, the operating mechanism, and the stock, hand guard and sling.
         (1) Barrel group. - (a) The barrel is 18 inches tong, cylindrical and without taper for two-thirds of its length. It is threaded into the forward end of the receiver, and in the rear face is a cut to furnish clearance for the extractor. To the muzzle end is attached the front sight group composed of a ring body with on integral blade positioned midway between two side wings keyed and pinned to the barrel.
        (b) A gas cylinder is positioned on the underside of the barrel near the chamber and contains the piston, locked in by the piston nut, which limits its rearward movement. A gas port is drilled at an angle through the gas cylinder and barrel, entering the bore about 4.5 inches from the rear face of the barrel. This rearward positioning of the gas cylinder and port makes it possible to take the gas from the bore close to the chamber, before cooling can take place, thus minimizing carbonization.

           

At this time there are two types of barrel and gas cylinder. In the first type the barrel and gas cylinder are integral; in the second type the gas cylinder slides onto the barrel and is retained in position by a pin.
         (c) On the lower sides of the barrel, to the rear of the gas cylinder,parallel guide grooves are cut, which mate with guide lugs on the body of the operating slide to form a guideway for the operating slide and hold it in position.In the left hand barrel groove is a relief cut, by means of which the slide body is positioned and removed. (Refer subparagraph (3) (d) below).
         (2) Receiver group. - (a) The receiver is of one piece, open at top and bottom, and contains the operating mechanism, and to it the trigger housing (mechanism) is attached. In the inner sides of the receiver parallel bolt guide grooves are cut, in which the bolt reciprocates and bolt lug locking apertures which are cut with a shoulder which holds the bolt locked in the closed position when cam-rotated by the operating slide at the end of the forward movement.
         (b) On the right outer side of the receiver is the operating slide retaining groove in which the rear end (handle) lug of the operating slide reciprocates when the slide is actuated by the piston and operatingslide spring respectively. In the top of this groove is arelief cut, by means of which the rear end (handle) of the operating slide is disengaged from the bolt. Slightly to the rear and below this relief cut is an aperture for seating the operating slide stop.
         (c) On the rear face of the receiver is a lug which engages in an undercut in the recoil plate (mounted in the stock) to lock the rear end of the barrel and receiver group to the stock. Below this lug, on the underside of the receiver, are two L-shaped lugs into which a T-lug on the rear end of the trigger housing slides and is retained. On the forward end of the receiver is a straight tug with a pin hole which aligns with pin holes in a mating U-lug on the forward end of the trigger housing. Through these aligned pinholes the trigger housing retaining pin passes to hold the trigger housing in position.
         (d) In the bridge of the receiver an aperture is cut with which the tong of the firing pin must mate in order to move forward in the bolt. This mating cannot be accomplished until the bolt is rotated to the locked position.
         (e) On the top rear of the receiver is the rear sight group composed of a base (dovetailed into the receiver), leaf, spring, and pin. The leaf is on L-shaped piece, consisting of two leaves set at right angles to each other, each pierced with an aperture at a different height. The leaf can be rotated 90 degrees on the leaf pin, thus positioning one or the other of the integral leaves, thereby giving sight elevations for two range limits. This construction necessitates one leaf remaining upright at all times. When the low leaf is perpendicular, the carbine is sighted up to 200 yards, and when the high leaf is perpendicular, up to 300 yards. (For shot grouping at 100 and 300 yards, refer to paragraph 50 c).
         (f) In the under side of the receiver is an aperture into which the magazine fits, and is retained by the magazine catch positioned in the trigger housing.
         (3) Operating mechanism group. - (a) The operating mechanism is composed of the bolt, the operating slide, operating slide spring, and spring guide. The bolt operates within the receiver, and the operating slide in its grooves on the right outside face of the receiver and lower rear faces of the barrel.
         (b) The bolt contains the firing pin, extractor and ejector groups and is connected to the operating slide by a lug on its right side, which mates with a camming aperture in the left face of the operating slide (handle). In line with this lug, and similarly placed on each side of the bolt, are locking lugs which engage in the receiver locking apertures already described.
        (c) The extractor is of the claw type, seated in an aperture in the top of the bolt and actuated by a plunger and spring. The ejector is seated in a well in the lower port of the bolt, locked in by the extractor, and actuated by a spring. The firing pin is seated in a well in the center of the bolt, is locked in by the extractor and has a tang on the rear end which blocks it from functioning until the bolt is locked, as already explained.
        (d) The operating slide is composed of an integral body and (retracting)handle. The body reciprocates in its guideways on the underside of the barrel, and the handle in its guideway in right outside face of the receiver. The function of the slide is to move the bolt backward and forward unlocking it from, and locking it to, the receiver at the proper time. The bolt in turn cocks the hammer on its rearward movement and feeds the cartridge into the chamber on its forward movement. The force to accomplish these actions is supplied by the backward thrust of the piston on the recoil stroke and the forward thrust of the loaded operating slide spring on the counter recoil stroke. The operating slide is provided with a retracting handle for retracting the bolt. On the shank of the handle is a lug which contains the afore mentioned bolt lug camming aperture. To the rear of this lug is the guide lug. The operating slide spring seats in a well in the forward face of the receiver, and acts on the operating spring guide, the forward end of which seats in an indentation in the rear face of the operating slide (body). In the rear end of the operating slide (handle) is a stop operated by a spring. The stop hangs the bolt when depressed and held into its retaining aperture in the operating slide (handle) guideway in the receiver.
         (4) Trigger mechanism group. - (a) The trigger (housing) mechanism group is composed of the trigger housing, trigger, hammer and sear, together with their component springs and pins, and the hammer spring plunger. The trigger housing is attached to the receiver at the rear, by means of a lug on the rear end of the trigger housing which engages with L-shaped mating lugs on the lower rear face of the receiver. The front end of the housing is held in position by a retaining pin passing through mating lugs on the forward end of the receiver and trigger housing and held in position by a spring. (Refer to subparagraph b (2) (c), above).
         (b) The trigger and sear rotate about the trigger pin and the hammer about the hammer pin. The hammer spring plunger seats in a notch in the rear face of the hammer shank and extends through an aperture in the rear of the trigger guard body, while the hammer spring bears upon the trigger housing and a collar on the plunger. The trigger spring is a U-shaped spring which fits in a slot in the rear end of the trigger, and an aperture in the rear end of the trigger housing. The rear end of the sear spring is seated in a well in the trigger body, the forward end in an aperture in the rear lace of the sear.
         (c) A safety is housed in the forward end of the trigger housing just forward of the bow. The safety is in the form of a cylindrical pin with a cut so fashioned that it clears or blocks the forward end of the trigger when the safety is pushed from side to side in its aperture. The safety is held in position by the safety plunger and spring. On the right side of the trigger housing just ahead of the safety, is the magazine catch. This catch functions in an aperture in the forward face of the trigger housing, and is held in engagement with two small lugs on the magazine by the magazine catch spring and plunger. The catch, when pressed, moves laterally to disengage it from the magazine lugs so that the magazine may be removed from the receiver.
         (5) Stock, hand guard and sling group. -(a) The stock group is composed of the stock in which the receiver and barrel are bedded, and the hand guard positioned on top of the barrel forward of the receiver. In the rear of the aperture in which the receiver is bedded, the recoil plate is positioned. This plate is secured to the stock by the recoil plate screw passing through the tang of the recoil plate and thence through the grip of the stock, and threaded into an escutcheon let in to the underside of the stock grip. The recoil plate serves to lock the rear end of the receiver to the stock as here to fore described, and to protect the wood of the stock from the hammering of the recoil mechanism. A recessed butt plate is screwed to the butt end of the stock by a wood screw.
        (b) To the rear end of the hand guard a metal liner is riveted, which protrudes slightly beyond the wood of the hand guard. This liner, when mated with an undercut in the top forward face of the receiver, secures the rear end of the hand guard to the receiver. The forward end is secured to the barrel by the front band which slides over the barrel and forward end of the stock and hand guard, thus securing all three together. The band is locked in position by a locking spring and screw.
         (c) A web sling is attached to a sling swivel mounted on the left side of the front band. In the rear end of the sling a loop is formed by means of a metal button passing through two button holes in the sling (recent style). This loop passes from the left side around the oiler, which seats in the right side of on aperture cut through the stock near the butt. The dimensions of the aperture through which the oiler is inserted prevents it falling out after the sling has been passed around it. Thus the oiler is held in the aperture by the sling, and acts as an anchor pin for the rear end of the sling. To the forward end of the sling a locking buckle is attached, by which adjustment of the sling is attained, after it has passed through the sling swivel.
NOTE: The oiler is cylindrical in shape and has a screw top to which a dropper rod is attached. It is used for lubricating the carbine as well as to hold the sling in position.
         c. The magazine is composed of a tube, base, follower, and spring. When loaded, the cartridges lie staggered in the tube and are pushed into line with the bolt, at the mouth of the tube, by the action of the follower and the follower spring, The mouth of the tube is narrower than the body of the tube and has its lips crimped inward. Thus one cartridge at a time is positioned and held in line with the bolt, ready to be pushed forward and loaded into the chamber as the bolt moves forward on the counter recoil stroke.

    3. DATA. --

Weight of carbine with magazine (unloaded)	pounds	5.19
Weight of carbine with  magazine (loaded) and sling	pounds	5.80
Weight of magazine (unloaded)	pounds	0.17
Weight of magazine (loaded) with  15 cartridges	pounds	0.59
Weight of 100 cartridges	pounds	2.79
Weight of 1 cartridge	grains	1.95
Magazine capacity	rounds	15
Overall length of carbine	inches	36
Length of barrel	inches	18
Rifling, R.H., one turn in	inches	20
Grooves in barrel	number	4
Sight radius	inches	21.46
Trigger Pull	pounds	4 - 6
Ballistics of cartridge	(Refer to Section VII - Ammunition)

NOTE: 7000 grains equal 1 pound avoirdupois measure.