TB 23-7-1
INTRODUCTION
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| Scope |
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| Description |
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| Data |
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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) | ||
| Weight of carbine with magazine (loaded) and sling | ||
| Weight of magazine (unloaded) | ||
| Weight of magazine (loaded) with 15 cartridges | ||
| Weight of 100 cartridges | ||
| Weight of 1 cartridge | ||
| Magazine capacity | ||
| Overall length of carbine | ||
| Length of barrel | ||
| Rifling, R.H., one turn in | ||
| Grooves in barrel | ||
| Sight radius | 21.46 | |
| Trigger Pull | 4 - 6 | |
| Ballistics of cartridge | (Refer to Section VII - Ammunition) |
NOTE: 7000 grains equal 1 pound avoirdupois measure.
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