US2372652A - Firearm - Google Patents

Description

FIREARM Filed Aug. 3, 1942 [L i I Y y i i l l I 1 i 5 Charles E-IE|E111E1'5 E11 Patented Apr. 3, 1945 FIREARM Charles E. Balleisen, United States Army, Philadelphia, Pa.

Application August 3, 1942, Serial No. 453,423

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to firearms.

An object of this invention is to provide a firearm of the type shown in Browning Patent 1,293,021, with means incorporated therein for assuring a minimum amount of gun failure due to cartridge case extraction difiiculties.

Another object of the invention is to provide a firearm of the U. S. standard Browning machine gun type, with means therein for assuring that the breech bolt and cartridge are in their farthermost rear locked positions with respect to the barrel before the cartridge is fired.

Another object of this invention is to provide means in a firearm for assuring a minimum amount of gun failure due to excessive deformation of fired cartridge cases.

Another object of this invention is to provide means in a firearm for assuring minimum and machine gun.

Fig. 2 is an enlarged view of modified bolt and barrel extension members similar to those shown In Fig. 1 and showing in greater detail the assembly of spring means between the bolt and barrel extension,

Fig. 3 is a section taken substantially on line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2 showing a modified spring means.

Fig. 5 is a detail of a modified spring member of rubber or similar resilient material.

Reference will be had to the disclosure in the The resilspring R so as to move the breech bolt E in its breech bolt has moved sufficiently rearward to take up all .play in the parts.

In adjusting the Browning machine gun, it is necessary to thread the barrel B into the barrel extension C so far that, when the bolt E is in its forward locked position, no play between the bolt E and barrel extension C exists. This operation is commonly known as adjusting the headspace. It has been found when play is permitted between these components, failure of the cartridge case by axial rupture, that is separation axially, is frequent. This failure is usually attributed to excess headspace, that is, a too deep cartridge chamber, even when the headspace is only a few thousandths of an inch in eicess of commonly accepted values. It is believed however, that this excess headspace is not he true cause of ruptures, as fin'ngs have been 0 ducted, in non-automatic guns when the readspace was approximately thousandths f an inch in excess, without failure of the car ridgecase. These firings were conducted wit the same lot of cartridges which had shown fl u es in a machine gun. Other known instanct exist where the play was very accurately adjusted, but

with a relatively large headspace, no pa t e case failures occurred.

In explanation of the above perfornance applicant believes the cause of cartridge'case fa11- ure resides in lost motion between thebolt E and barrel B when the bolt is not held firmly and against rearward movement in its licked p tion: and this lost motion is attributed to disparity in mating dimensions presen; when, guns are made by production methods. on this basis, it is possible, when the mechanism'goes forward prior to firing, for the bolt and cartridge to be jolted into and remain in their fai'thermost forward positions with respect to the barrel. Upon firing, the propellant gas causes the cartridge case to expand and the forward end of the cartridge'case' being thinnest expands first and grips the chamber and thus releases the bullet; the ammunition cartridge gases then push the cartridge case to the rear. If the bolt E is not rigidly supported, it will move relative to the barrel B, and the cartridge case will elongate longitudinally as its rear end is pushed against. the face of the bolt E while the front end is gripped by the barrel chamber wall. ,As, however, the walls of the cartridge case are cold worked and cannot withstand much distortion, the case may separate into two pieces.

It is important that the cartridge case be held firmly in the barrel, 1. e., no movement of the breech bolt E relative to barrel B should result when and as the cartridge is fired. Herein lies one important phase of the invention, namely, to provide means for firmly supporting the cartridge case against the breech bolt face and to secure the: bolt. E against movement relative to the barrel B" so that gas-pressure'can act only to deform the shoulder and neck of the cartridge case whereby those elements tend to conform to the shape of the barrel chamber.

From the foregoing description it is apparent that the rupturing of cartridge cases. may be prevented by insuring that the cartridge case and bolt are in their rearmost lock position before firing. This can be accomplished by means of springs or other expanding devicesv of, low strength, which strength need only be sufficient to overcome the inertia and friction of the: parts to be moved to their rearmosti position. and the initial, force of the reaction spring R. These spring elements may be placed wherever the configuration of the parts conveniently permits; however, it appears most practical toplace them within the rear end'of. the modified barrel extension C as seen in Fig. 2 to act with the rear downwardextension of the modified breech bolt E,'. It. is noted that the modified barrel extension C and'modified bolt E have structure similar to that of corresponding elements in Fig. 1 and'in the Browning Patent 1,293,021 and have identical'functions. A pair of helical springs I0, I I are shown in Fig. 3 but it is apparent that one or a plurality of leaf springs l2; Fig. 4, may be iubstitut'ed for the helical springs I, I I, or small Wlinders l3 (Fig. 5) of highly; elastic material such as rubber may also be employed instead of cyindrical helical springs I, H.

n Figs. 2 and 3thesprings H]; H are received ant held. in barrel extension recesses 14, I5. In Fig.4 curled leaf spring 12 is held in the downwarlly extending portion of breech block E.

Inzhe prior art practice as seen in the Brown- Patent. 1,293,021,,the reaction spring R tends to mme the boltE as far forward as, possible and barrel extension C is moved as far forward as possible by the tension of the spring on the pisn Q- It is quite apparent that no means are discloses in. the Browning Patent 1,293,021 for takingu play and assuring positive engagement,

betweenv the breech bolt E and. locking block N; the. spring devices or resilient means which overcome the effect of reaction spring R assure positive engaglment of the bolt E against locking blo ck.N ani thus positively maintain, the bolt E andlcartridge in. their farthermore rear position with respect to the barrel 3.

I claim: a

1.. In:a firearm having a recoiling barrel and a rearwardly exzendingbarrel extension, a breech bolt; means-for locking the breech bolt and barrelextension together against relative axial movement intheir firingposition said locking means of the type subject to, axial play when in locked position, and a spring urging. the breech bolt forward; the. improvement comprising, resilient means interposed between. the breech bolt and barrel extension and bearing, directly on each,

and stronger than said spring when the latter is in expanded condition, said stronger resilient means being adapted to take up play between the breech bolt and barrel extension incident to the bolt locking means when said bolt and extension are in firing. position, thus assuring that when said bolt and extension are in such position, the cartridge and bolt are in their furthermost rear position with respect to the barrel at the time of firing the cartridge.

2. In a, firearm having a breech bolt, a recoiling barrel, a barrel extension, a locking block carried by the extension for locking the bolt and extension together against relative axial movement in firing position said locking means of the type subject to axial play when in locked position, means for actuating the block to effect such 1ocking during the forward movement of said bolt and extension, and a breech bolt spring urging said bolt forward; the improvement comprising a separate spring interposedbetween the breech bolt and the barrel extension and'bearing directly on each, and stronger than the breech bolt spring in its expanded condition and" adapted to take up play between the breech bolt and barrel extension incident to the locking block when in locked position, thereby assuring engagement between the bolt and the barrel extension and the maintenance of the bolt and cartridge'in the barrel in their furthermore rear position with respect tothe barrel at thetime of firing the cartridge.

3. In a firearm'having: a -recoiling' barrel having a cartridge case chamber allowingexpansion of the cartridge case within' the limits incident to the thermal condition in the cartridge case chamber when the cartridge is fired and a rearwardly extending barrel extension, a breech bolt, and means for locking. the: breech bolt and barrelextension together in their firing positionsaid locking means of the type' subject to axial play when in locked position, the improvement comprising resilient means directly engaging the barrel: extension: and: bolt and urging the latter to its furthermost rear position by taking up the 2 play inthe bolt locking means, thus assuring that the cartridge as well as the bolt are in their Iurthermost rear position withrespect to the barrel at the time of firing the cartridge.

4. In a firearm, a recoiling barrel having a chamber for insertion of a cartridge and-a barrel extension having a rearwardly disposed face, a breech bolt slidablymounted in. thebarrel extension, a recoil spring urging saidlbolt to firing position, said bolthaving a portion extending substantially parallel with the barrel extension face, bolt locking means carried by the barrel extension for locking the bolt and barrel extension together in firing position said locking means of the type subject to axial play when in locked position, and a spring stronger. than the recoilspring when said recoil spring is iniexpanded position, said spring being interposed between said bolt portion and barrel extension face, bearing directly on each, and urging the bolt tolitsfurthermost rear position against the bolt locking means at the timeof firing the cartridge.

CHARLES E. BALLEISEN.

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