US2868082A - Drop lock bolt for gun - Google Patents

Description

Jan- 13, 1959 R. G. NUTTING Em 2,868,082

DROP LOCK BOLT FOR GUN Filed Oct. 13, 1955 Zay INVENTOR. Rnherl E Nuingf BYRDEETL mnargp Zbd Patented Jari. 13, 1959 DROP LDCK BOLT'FOR GUN Robert G. Nutting, Glenview, and Robert F. Windstrup, Chicago, Ill., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Application October 13, 1955, Serial No. 540,362

3 Claims. (Cl. 89-190) Our invention pertains to a machine gun and more particularly to a gas-operated bolt therefor.

In the usual machine gun including a receiver, a feeder for conducting an ammunition belt therein and a bolt spring, a bolt operates in rearward kand forward strokes, from and to a battery position, responsive to discharge of cartridges in the barrel. The bolt includes enough mass and the rate of the spring is high enough to store kinetic energy from the discharge to operate the feeder, to strip live cartridges from the ammunition belt, to ram the cartridges from the feeder into the barrel and to extract the cases of the cartridges from the barrel after the discharge. The rate of fire of the gun is inversely proportionate to the mass of the bolt and the rate of the spring.

The machine gun of our invention is provided with a feeder for supplying cartridges to a feed throat` to eliminate the feeding and stripping functions of the bolt and thereby reduce the kinetic energy required to be stored by the bolt to increase the rate of the gun.

Itis an object of our invention to provide a gas-operated bolt mechanism for such a gun.

Another object of our invention is to provide such a mechanism having separate bolt and rammer components.

A further object of our invention is to provide such a bolt component having an inertia member and integral means for locking the component in the battery position thereof.

A still further object of our invention is to providesuch a gun with a rammer for operation responsive to displacement of the bolt.

Other aims and objects of our invention will appear from the following discussion thereof.

In carrying out our invention, the gun is provided with a bolt biased by a spring to a battery position adjacent the breech end of the barrel to chamber a cartridge therein, and the bolt is operable in rearward and forward strokes responsive to discharge of the cartridge to extract the case of the cartridge from the barrel, subsequent to the discharge. oted on the receiver and connected by a link, is disposed to project a cartridge from the feed throat into the barrel, responsive to the rearward stroke.

The bolt of our invention is neither required to operate the feeder nor to strip cartridges from the ammounition belt. And, since the rammer is a separate component, it may readily be seen that the mass of the bolt and the rate of the spring included in the gun of our invention may be considerably less than those of the usual gun to increase the rate of re of our gun.

For a more complete understanding of our invention, reference is directed to the following description and the accompanying drawings in which:

Fig. 1 is an elevational view, partly in section, of a machine gun incorporating our invention;

Fig. 2 is a view of one of the lbolt locks in operating position;

A rammer, including a pair of levers fpiv- Fig. 3 is an enlarged view along line 3-3 of Fig. l;

Fig. 4 is an enlarged view along line 4 4 of Fig. 3;

Fig. 5 is a view similar to Fig. 4 with the inertia member displaced rearwardly; and

Fig. 6 is a perspective view of the lock member.

Accordingly, a machine gun 12 including a receiver 14 is provided with a barrel 16 and a barrel extension 1S secured thereto. a bifurcated portion thereof, and a bolt 22 is mounted for sliding movement parallel to the longitudinal axis of barrel 16 by means of a pair of laterally-opposed rails 24 which are received by cooperating grooves 26 in tines 20.

Springs 28 engage -receiver 14 to bias bolt 22 to a battery position for breech engagement of a surface 30 thereof with the base of a cartridge 32 to chamber the carfridge in barrel 16.

Barrel extension 1S includes a piston 34 which is e11- gageable with an impact member 36 sldably disposed in bolt 22 and secured therein by an insert 3S held in bolt 22 by a pin 40. A spring 42 biases member 36 towards a normal position of engagement with insert 33, and an extension 43 of member 36 projects from bolt 22 for battery position engagement with piston 34.

A firing pin 44 is disposed for battery position engagement with the primer of cartridge 32 and insulated from bolt 22 by a cylinder Li6 of nonconductive material.r A hook 48 is pivoted on bolt 22 and biased by a spring 49 for engagement with the extraction groove'of cartridge 32.

Bolt 22 includes sides 50 and corresponding lock members 52 are pivoted at 53 in outer recesses 54 of the sides between operating and locked positions. Lock members 52 are provided with trunnions 56 which extend outwardly to be received by cooperating L-slots S8 provided in member 36. In the operating position of member 36, trunnions 56 are disposed in branches 59 of slots 58. Members 52 include extensions 6d disposed to continue rails 24 and be slidable in grooves 26 when the members are in the operating position and thereby slidingly support bolt 22 to permit bolt 22 to slide in barrel extension 18, and to be pivoted out of alignment with such rails and into engagement with a pair of stops 62 of barrel extension 18 when such members are in the locked position to secure bolt 22 in the battery position thereof.

A cylindrical case 64 including a hanged portion 66 corresponding to a shoulder of member 36 is secured therein by an insulating spacer 68. A `cap 76 is threaded to casing 64. A rod 72 and a ball 74 cupped in cap 70 are biased apart by a spring 76 for engagement of a shoulder 78 of rod 72 with spacer 63 and for engagement of ball 74 with tiring pin 44 through a slot Sti in cylinder 46. Rod 72, ball 74 and spring 76 are electrically insulated from bolt 22.

-Rod 72 extends through spacer 68 for battery position engagement with a spring-biased contact 82 of a terminal 84 electrically insulated from barrel extension 18 to conduct electric current to the primer of cartridge 32 for discharge thereof.

Gases from the discharge operate on piston 34 for displacement of member 36 rearwardly in bolt 22. Cam surfaces 86 are provided in slots 53 for engagement with trunnions 56 for displacement thereof to branches 88 of slots 58 and consequent displacement of members 52 to the operating position during the rearward displacement. When trunnions S3 are positioned in Ibranches 88 member 36 engages a surface 9i) to urge bolt $22 in a rearward stroke against springs 28.

The case of discharged vcartridge 32 is carried rearwardly by bolt 22 and the case is rotated out of engagement with the bolt responsive to engagement of the base of the case with a stop 92 disposed on receiver 14.

Live cartridges 32 are supplied to a substantially cylin- Barrel extension 18 includes tines 20 ofy drical throat 94 by a feeder (not shown) responsive to the discharge, and a rammer 96 includes a pair of levers 98 and 100 pivoted on receiver 14 with a link 102 connected therebetween. Lever 98 is biased free from engagement with a cartridge 32 disposed in throat 94 by a spring 104 secured to receiver 14.

The axis of cylindrical throat 94 intersects the axis of barrel 16 at the breech end thereof, and a cam 106 is provided on bolt 22 for engagement with lever 100, to sequentially project the cartridges from throat 94 into barrel 16, responsive to the rearward strokes of bolt 22.

Bolt 22 operates in a forward stroke responsive to spring 28, and as the bolt arrives at the battery position, member 36 is returned to engagement with insert 38 responsive to springs 42, and members 52 pivot to the locked position. Electrical contact between firing pin 44 and contact 82 is broken as member 36 is displaced rearwardly, and the contact is completed again when member 36 returns to the normal position.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

We claim:

l. In a machine gun including a barrel and an extension member mounted on the breech thereof, a bolt device comprising a bolt member actuatable between a recoil and a battery position, a bifurcated portion in the extension member to'slidingly receive said bolt member, a pair of tines formed by said bifurcated portion and disposed for sliding engagement with the side of said bolt member, a groove extending along the inside of each of said tines parallel to the longitudinal axis of the barrel, supporting means extending from each side of the bolt member for sliding cooperation with said grooves, means for pivotally interrupting said supporting means when tracks, means for pivoting said lock members to move said extension portions out of alignment with said grooves when said bolt member is in battery position, and stop portions in the extension member engageable by said extension portions when said lock members are pivoted to move said extension portions out of alignment with said tracks for blocking said bolt member in battery position.

3. In a machine gun including a barrel, an extension member mounted on the breech thereof and a piston energized by gases generated in the barrel during operation of the machine gun, a bolt device comprising a bolt member actuatable between a recoil and battery position, a bifurcated portion in the extension member for slidingly receiving said bolt member, a pair of tines formed by said bifurcated portion and disposed for sliding engagement with the sides of said bolt member, a groove extending along the inside of each of the tines parallel to the axis of the barrel, an impact member slidingly mounted on said bolt member for movement between a forward and rearward position, said impact member being disposed for engagement by the energized piston when in the forward position, engaging portions on said bolt and impact member for transferring the energy from the piston to said bolt member when said impact member is in the rearward position, longitudinally-disposed track portions extending from the sides of said bolt member to be slidingly received by said grooves, recesses formed in each side of said bolt member to interrupt said track porsaid bolt member is in battery position to block said bolt t member against rearward displacement, and stop portions in said extension member engageable by said supporting means where interrupted for releasably blocking said bolt member in the battery position.

2. In a machine gun including a barrel and an extension member mounted on the breech thereof, a bolt device comprising a bolt member actuatable between a recoil and a battery position, a bifurcated portion formed in the extension member to slidingly receive said bolt member, a pair of tines formed by said bifurcated portion and disposed for sliding engagement with the sides of said bolt member, a groove extending along the inside of each of said tines parallel to the longitudinal axis of the barrel, lock members pivotally mounted on opposite sides of said bolt member, means cooperating with said grooves to slidingly support said bolt member for movement between a battery and recoil position including tracks extending from said bolt member for sliding cooperation with said grooves and extension portions disposed on said lock members for alignment with said tions, a lockmember mounted in each of said recesses for pivotal movement between an operating and lock position, extension portions on said lock members disposed to continue said tracks when said lock members are in the operating position, stop portions in `the extension member engageable by said extension portions when said lock members are in the lock position to block displacement of said bolt member from battery position, trunnion portions extending from said lock members, and slot means in said impact member operationally cooperating with said trunnion portions for pivoting said lock members from the lock to the operating position during movement of said impact member from the forward to the rearward position.

References Cited in the file of this patent UNITED STATES PATENTS 1,430,661 Lewis Oct. 3, 1922 2,098,727 Lahti Nov. 9, 1937 2,378,331 Schirokauer June 12, 1945 2,466,929 Catlin et al. Apr. 12, 1949 2,487,198 Swebilius Nov. 8, 1949 2,577,026 Maillard Dec. 4, 1951 2,590,981 Lippert et al. Apr. 1, 1952 2,594,770 Hammer et al. Apr. 29, 1952 2,615,370 Koucky Oct. 28, 1952 2,642,779 Trevaskis June 23, 1953 2,714,334 Harvey Aug. 2, 1955 2,746,357 Dixon May 22, 1956

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