US1603684A - Automatic gun - Google Patents

Description

Oct. 19 1926. 1,603,684 J. c. GARAND UTOIATIU GUN Filed SSP?" 5. 1919 4 Sheets-Shoot 1 4 Sheets-Sheet 2 J; c. GA'RAND AUTOMATIC GUN Filed Sept. 5; 1919 ou, 19 1926..f

J. tc. GARAND AUTOMATIC GUN I Filed Sept.

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Patented Oct. 19,' 1926.

UNITED STATES PATENT OFFICE;

JOHN c. GARANnOF SOMERSET, MARYLAND.

AUTOMATIC GUN.

, Application med september 5, 1919. serial No. 321,956.

'i'nis invention relates to improvements in automatic firearms and more especially to that class of automatically loading tirearms in which the forces derived from the explosion of the cartridge are utilized to expel the spent cartridge and reload the and disassembled, and which is capable of being fired either singly or with repeated automatic action at the will of the operator. The present invention difers in several essential points from lmy prior invention as set forth in application filed July 11, v1919 bearing Serial No.l 310,249. In the prior application mentioned, the gun mechanism is so designed and constructed 'as to utilize the power of theV lprimer to actuate the automatic parts. Experiments have shown that there is a wide variation in the amount of power produced by primers uti-` lize'd in various standard makes of cartridges,l Vand this is true even in cartridges which have approximately the same ballistic properties. It is Obvious that the continuousl operation of an automatic machine gun that depends alone upon the force from the primer', is lia-blev to be interrupted if oneprimer should fail to deliver the force required to actuate the mechanism throughoutits cycle. Furthermore it has been demon.

strated with this type of gun' that delicate and troublesome adjustments in the relative masses and tensiommeans of the actu. ating mechanismare necessary, .1n order to 4 compensate for varying amou'ntsv of force derived from the. primers of standard car-1A Y tridges,- Therefore '1n-the improved vtype of gun embodied inthe present invention a novel breech mechanism is provided, which lmechanism utilizes a combination of forces VVrwhiglijorces may be enumerated as follows The recoil ofthe gun, the limited'l rearward movement of the cartridge in conined posi- 5 tion, the rearward' movement of theprimer relative to the cartridge, and the rearward movement, or blow back of the vcartridge after becoming released from the firing chamber. l A

present invention involves improvements in the general construction of -irearms which improvements, in combination .with'1 neansv for actuating the mechanism of an 'automatic machine rifle, will permit'the inter- 60 changeable use of standard makes of cartridges without requiring 'adjustments and which will provide further advantages asv will hereinafter appear.-

`One feature of this invention ispa provision of a specific breech mechanism in which'the cartridge is inserted 'into the gun barrel -at the instant offiri i thereby eliminating the danger of accntal explosion which is likely to occur in rapid. rifles ..70 when the cartridge is `allowed'to Yeven momen'tarily remain in the explosion chamber when the gun has become-heated to a deree suiiicient to caus e a-'spontaneous comy ustion of the explosivesln the cartridge.

Another feature of this'inventionrlates to a novel actuatorand breech bolt vso coacting as to insure the' itive operation of the firing pin in explo thecartridge, and also permitting operation of Athe actu- "30 ator and bolt by the ring in, inthe manner to be hereinafter descrl ed.

Another feature of 'this invention-relat`es fto a novel construction of. the Atrigger mechanism, which positively controls'the 85 automatic action of the gun, whereb it may be' fired'either singly Or repente y, bya

simplemanipulation of the trigger. Y

"Another feature of this'invention relates f to a novel construction of the receiver and stock bracket, which' allows theentire receiver and barrel, with their associated` parts',

to. -be. readily separated. from; the stock bracket and associated parts, 'by al simple manipulation of a single lockmgrbolt. Y derived .from the explosion of thecartridge,

Another feature relates. to a novel .con-

of the rie mechanismitobeeasily a It will, therefore, be observed that the. 5fl

`the cartridges into the explosion chamber.

The vinvention consists in certain novel features of construction and arrangement of parts as will be hereinafter' described and pointediout in the claims,

Figure 1 shows the longitudinal cross section of the riie in cocked position.

Figure 2 shows the longitudinal cross scction of the riie at the instant of iring,vwith the trigger mechanism held in position for re eated firing.

gure 3 is a longitudinal cross section of the un showing the position of the breech meck anism immediately after the gun is fired with the trigger mechanism in position for aV single sho Figure 4 is a top plan view of the receiver or casing.

Figure 5 is a bottom plan View of the receiver or casing.

Figure 6 is a rear view of the receiver or casing.

Figure 7 is a fragmentary detailed View of the rear end of the barrel, and locking means therefor.

Figure 8 is a side elevation of the actuator and breech bolt assembled.

Figure 9 is a top View of the breech bolt. b Figure 10 is a bottom View of the breech Fi re 11 is'an enlar ed fragmentar detaileu cross-sectional iew of the bi'leech bolt, showing the extractor and the ejector in operative engagement with a cartridge;

Figure 12 is a front view of the breech bolt with part f the cartridge shown in section.

Figure 13 is a rear view of the breech bolt.

Figure 14 is a detailed View of the extractor.v

Figurel 15 shows the side elevation `of the trigger mechanism frame and cartridge ejector. i

Figure 1G is the front View of the trigger mechanism frame and cartridge ejector.

Figure 17 is a fragmentary View in elevation of the lett hand side of the rifle.

Figure 18 is a fragmentary view,in elevation of the right hand side of the rifle.

Figure 19 is a detailed view sembly locking bolt.

Figure 2O is a cross section'of assembly locking bolt taken on line 20-20of Figure 19.-and shown in three positions, namely: ready, safe, and take-downv positions.

Referring to the drawings..,tbe riiie embodying the present invention may be mounted on a gun stock 1 'of the usual military type, with a, stock bracket 2 Seated therein and secured by suitable bolts 3 and 4:. The stock bracket 2 `comprises a trigger guard 5, an elongated housing 6 adapted to receive the trigger mechanism 7, and a magazine compartment 8 adapted to receive a cartridge magazinel9 of any approved pattern containing a plurality` of cartridges 10. 10, in position to be automatically sup-y `and detachably connected therewith by means of a T-slot 15 at the rear end of the' receiver, the T-slot being engaged by the lug 16 extending upwardlyfrom the rear end of the stock bracket, and by a lug 17 extending upwardly from the front end of the stock bracket, said lug. 17 being adapted to engage a recess 19 in the receiver, and an adjacent recess 18 formed in the rear end of the rifle barrel 13 (see Figure 7). The rear face of said lug 17 is further provided with a cam surface 20, which forms a scoop to guide the cartridges intoI the explosion chamber 2l during the operation of the gun.

In mounting the receiver.. on the stock bracket, the receiver is brought intoengagement therewith so that the T-slot 15 on the receiver engages the lug 16 on the stock bracket, and SOthatAthe lug 17 is positioned in the recess 18 in the rifie barrel, and recess 19 in the receiver: then by turning the bolt l2, (see Figures 19 and 20) the cam 12a engages with the notch 11n of the receiver and locks the receiver against end-wise move` ment on lthe stock bracket. With the receiver and barrel thus locked in place on.

the stock bracket, said lug 17 serves to check the recoil 'of the barrel and receiver, 4also retains the receiver on the stock bracket and v The bolt 12A also acts as a lock for the actuating mechanism as Will hereinafter be described.

lThe main elements of the reciprocating breech mechanism are mounted in the ree ceiver 11 and comprise a breech bolt 22 which is rotatably locked in a forward inthe receiverL an actuator 23 slida non-rotatably mounted in said receiver and havingconsiderable mass in relation to said bolt, and a main operating spring 24 in theV rear end of said receiver, normally under compression tending to force the actuator and bolt towards the front end of the receiver. The breech bolt is locked and un' ppsition ly but locked, to confine a cartridge in the firing chamber 21, in the following manner: The bolt is providedwith a rearwardly extending p'ortio 223 projecting into a suitable recess 23a in the actuator, and carries a pair of 'laterally extending lugs 25, 25 adapted to engage in camways 26, 26 on the actuator, said lugs and camways being 'so constructed as torotatethebolt as the bolt moves longitudinally ,in the actuator. The forward portion, or bolt head 22h, of the breech bolt 22 isn rovided witha plurality of locking lugs 2 ,.27 on opposite sides thereof, adapted to enter recesses 28, 28- formed between lugs 28", 28a in the front end ofthe receiver, and a guide iin 29 which moves in the longitudinallyextending groove 30, in thel top wall of the receiver. While the bolt is in lockedpositi'on in the front of the receiver,

and the locking lugs 27 27 are engaged in` the v'recesses 28,28, the actuator and boltoccupy a position in relation to each other as shown in Figures 2 vand 8, in which the lugs 25, on the boltare in their rearmost positionl in camways- 26, 26 on the actuator, and the guide lin 29 is in an offset portion 3l of the groove 30.- The actuator 23- is held in-forward position by tension ofA a' spring 24, and at the instant of explosion of the cartridge is caused to be moved rear.- wardly scribed. e

As the actuator moves away from the locked breechbolt, the later is rotated by the action of the lugs 25 in the camways 26, 26 so as to move the locking lugs 27, 27 out of locking engagement with the recesses 28, 28 of the receiver, and also move the guide fin 29 into the'longitudinal portion of the guide groove 30.

lt will be observed, however, that the actuator moves a short distance rearwardly before the boltjbegins to be-rotated, and the unlocking action of the bolt is therefore delayed momentarily 'after the cartridge is red. This is because of the shape of the camways 26, 26 (see Figure-8) which allow the actuator to move a substantial distance irrespective of the bolt, additional movement of the actuator beingoperative to cause the lugs'25, 25`to engage the inclined uideways and rotate the bolt out of locked! position. rlhe amount of rotation of the breech bolt is limited by the guide fin 29, which allows thefsuilicient rotation of the bolt to unlock,

in ,a 'manner to be! presently de-f required to overcome this friction, and to unlock the bolt. l have experimentally de. termined this angle of repose to be approximately 83 degrees, but this may vary somewhat according to the smoothness of the engaging surfaces or the amount of lubrication of the parts.

The actuator 23 is provided with a finger piece 23, (see Figure-'18) extendingfrom the right side of the receiver 11, and moving in recess 11, formed in the bottom wall of said receiver forthe purpose of retractin'g the actuator by hand when it is desired to cock the piece. A rearwardly extending shield 23 is attached to said actuator, serving to close the rear end of the recessllc against access of rain, dirt, or other` foreign matter.

In the construction` above described, fit will be observed that one source of power for actuating the` gun mechanism is provided by the recoil of the gun. Experiments. have shown that the recoil of a rie weiglr ing approximately ten (10) ,pounds andring a standard U. S. cartridge, gives a rearward acceleration to the mass ofthe gun amounting to approximately twelve (12)y feet per second. This' rearward-acceleration affects the whole mass of the gun, but the rearwardmovement of the gun is checked by the shoulder of the operatorhor other vsupporting means, in the usual manner.

The actuator 23, however,- being in unlocked relation to the gun, is free to move rearwardly 'against the main operating spring 24, and to exert thereagainst the momentum imparted to its massI by the recoil, to startthe actuatingmechanism in operation. rIhe amount of force derived by the actuator from this source is relative only, and depends upon the rapidity with which the acceleration of the gun itself is retarded and overcome -by the shoulder of the operator,

llO

or other supporting means; but at all events,

the force thus derived has been found to be of substantial assistance, in combination with Vother forces hereinafter disclosed, to provide energy for actuating the automatic mechanism.

The mechanism for utilizing the power derived directly from the explosion of the cartridge comprises a firing pin 32 in the bolt head 22". Said firing pin is prefer-l ably\provided.with a striking face 32?, sufficiently large to engage the entire area of a standard cartridge primer, and having a firingipoint 32", in the center thereof. The ring pin is further pi'ovided with a flanged portion 33, which engages a shoulder 34 inn the cartridge is not pushed to its innermost position in the firing chamber, but is moved a short distance further therein by the firing pin as the gun is fired.

The gun mechanism is held in cocked position as shown in Figure l with the actuator and bolt retainedin a retracted position in the rear end of the receiver. In this position the actuator is spaced from the rear end of the firing pin and held by a sear 44, as will be described. When the sear is released, the actuator and bolt are moved forward by the spring 24, and as the bolt is being rotated to locked position as hereinbefore described, the forwardly extending portion 23b of the'actuator approaches the firing pin 32 and forces it against the primer 10ZL o'f the cartridge 10, as shown in Figure l2. Owing to the construction of the firing chamber and bolt, as above described, the entire cartridge will be forced by the firing pin to its innermost position in the firing chamber, forming a head space between the bolt and the cartridge before the primer is detonated b y the firing pin. 'The subsequent explosion of the cartridge, as is well known, generates a large pressure of gas in the firing chamber, which expels the projectile through the rifle barrel and at the lsame time tends to force the cartridge rearwardly against .the breech bolt. The cartridge will therefore be thrown rearwardly through the head space between the bolt and catridge until it is checked against the locked breech bolt. The ring pin, bein@ in contact with the primer, will b e thrownblrearwardly with the cartridge, and the impulse of this movement is transmitted through the firing pin to the actuator, and serves to give it a rear` ward acceleration which is utilized to unlock`the bolt and further actuate the mechanism.

The purpose of this novel construction which utilizes the limited movement of the cartridge while the bolt is in locked position isvras follows: It is a well known fact that those military types of cartridges having a reduced portion at the forward end of the cartridge case cannot be immediately withdrawnfrom the explosion chamber after firing, because of the danger of bursting the cartridge case. Consequently, it.\has heretofore been the usual practice to rigidly `secure the cartridge in its place'by retaining the breech bolt in its locked position until the pressure in the explosion chamber has become sufliciently reduced to allow the cart-ridge to be safely withdrawn; However, I have experimentally demonstrated that the` cartridge. may be allowed to move rearwardly a limited distance at the instant of explosion, Without danger of bursting orv otherwise injuring the case, provided thel` rearward movement does` not exceed approximately .015 of an inch. I have, therefore, provided the above described construction to utilize the direct force of this movement, vwhich force, if the cartridge were securely locked against movement, would be transmitted directly to the body of the rifle. I have found that the best' results are' obtained by allowing a head clearance of approximately ten one thousandths (.010) of an inch between the cartridge and the bolt after it islocked. The importance and magnitude of thisv impulse, or acceleration, though carried through but a short distance, is more readily understood when it is pointed out that the standard U. S. cartridge has been found by experiments to exert a lforce of approximately 12,000 lbs. on the breech bolt at the instant of firing.

The construction herein described also affords a further source of power for utilizing ited rearward movement of the primer in excess of its movement with the cartridge. As has been above described, -the limited rearward movement of the cartridge-case and primer transmits an impulse to thel actuatorthrough the firing, pin. The gas pressure generated in the cartridge, however, is amply sufficient to force the primer beyond its normal position in the cartridge, after the movement of the cartridge has been checked by the bolt. Consequently. the firing pin '32 is so arranged that it may. be moved rearwardly by the primer through an additional distance into the face of the breech bolt, (see-Figure 3.) thereby affording an additional acceleration to the actuator. The rearward movement of the lprimer and firing pin is limited by the shoulder 34 as shown in Figure 3, as it has been found inadvisable to allow the primer to come out of the cartridge before the firing pin is brought to rest.v It will be observed that the face 32 of the firing pin is so dimensioned as to be of approximately the same diameter as the cartridge primer illustrated, yet it is obvious that theface of the firing pin may be made substantially larger in diameter than the primer without materially affecting the action of the respective parts. I have demonstrated that many different makes of cartridges, havingr varying sized primers, can be used with uniform shccess in my rifle, without necessitating any change in the construction of the firing pin, or associated.l

- ent invention this force is utilized as van 410 inches long when uncompressed.

values may be changed'somewhat depend-v vface of the bolt head 22h.

auxiliary to the before mentioned forces in operating the moving parts.

I find that it is necessary that the recprocating parts which receive energy from the force derived yfrom the explosion as described, should lhave a certain minimum' weight i-n order that they may accumulate energy suicient to carry out the operations or' lejecting the cartridge and inserting Ia fresh one, and to overcome the lfriction of the parts in passing through a cycle oi." operations. Also the spring must be capable of storing suliicient energy to return the reciprocatingparts from their rearmost position to the cocked position, and to force the parts home to locked and firing positicn. I have found by experiments that good results are obtained when the actuator weighs about 11/1 lbs. and the spring is of spring wire (.073 in. diameter) coiled into a helix about These ing upon the ballistic properties of the car-- tridge used, or when it is 'desired to vary the'speed of the operation of the gun.

The mechanism V.for extracting the ex# panded lcartridgefiom the firing chamber and ejecting the same -from the rifle, comprises a laterally movable extractorl 36, mounted in a socket 36, formed in the front Said socket is provided with undercut walls adapted to re-` tain the laterally extending flanges 38 on thev extractor so. constructed as tol-permit a re-v taining Alip 39, formed on'the extractor, tobe moved into engagement with the cartridge flange 'Said flange 10b is adapte-dto t into a recess v37 formed i'n the'front face 'of' the bolt head 22". (See Figures 11, 12and 14.) A small compression spring 37a tends to vretainthe extractor in positionto ,engageV with the cartridge' flange. The extractor and spring may be inserted in the recess 36 while the retaining ring 35 is out of its posititin in the bolt head. When the re` taining ring is replaced, the extractor abuts the edge of the ring and is held .in position as shown. 'In order to ited movement'of the cartridge 1n the firing chamber after the bolt becomes locked, it is necessary to provide for a small amount of allow for the lim.

gagement'with the 'actuator end-wise movement of the cartridge flange.

under the retaining lip 39, as is in icated at 39a (see Figure 11). As the bolt forces the cartridge into position in the firing chamber, the cartridge lange becomes seated in the recess-37 and is engaged by the retaining lip 39 of the extractor. As Jche bolt becomes unlocked 'and moves rearwardly, the cartridge 'is drawn rearwardly therewitliuntil the bolt reaches a position substantially as shown in Figure 1. At this instant a suitable finger 40, (see Figure l1) formed integrally with the frame member 41 0i the trigger mechanism, extends into the path of l the cartridge case by reason of the incut 37 a in the edge of the bolt, (see F igue 1,2) and comes into contactwith the edge of thc'cartri'dge case at a point opposite the ejector .as shown in Figure 11, so that the cartridge is flipped out of the recess 37, and is ejected from the Aaperture 42 lformed in the side wall of the receiver. p

A pairof anges 43, 43 extend upwardly from the stock bracket into the rear end of the receiver for the purpose of'. retaining the operating spring 24 in longitudinal position.

I `have provided a series of grooves 11", 11b, extending longitudinally in the interior walls of the receiver, which grooves serve to facilitate the conductance of heat generated in the rapid" lfiring o the riie and also to lighten the construction ofl the gun.

The automatic trigger mechanism 7 is seated in a suitable -housing 6 in the stock bracket'v and comprises a trigger frame 41,' a sear 44 and trigger45. aid'sear 44 is mounted on a pivot pin 44", and has limited longitudinal movement thereon by reason of the slot 44'. A suitable spring 46 is provided` so positioned as to normally force the sear rearwardly and upwardly, into engaging position with the detent or catch 23 on the actuator. The trigger 45 comprises a rocking arm pivoted on pin 45 having a. Sear-engaging head 46 which extends through an aperture 47 betweenthe endsof the scar, and is adapted to engage the top surfaces 48 or 49, depending upon whether it. is desired to hold thesear 1n position to permit the Vgun to tire a single shot or to fire repeatedly, as will hereinafter be described.

j V4In the position ofthe trigger mechanism shown in Figure 1, the' gun isshown inv cocked, position with the detent' or catch 23, 'of the actuator in engagement with the Sear.A In this position, the lforce. of the 1main operating spring 24 is suliicient to overcome the4 force of the' spring 46 of the sear and to force the searto, a forward position as shown. 'with the. rear end of the trigger BCL head '46 hooked over Ythe surface 49 of the Sear. -As the trigger .is pulled in the usualv manner, the sear is 'depressed -out of entorethegun.

lic

, spring 46 acting on the Sear is sufiicient to throw the sear rearwardly to a position. l

shown in Figure 3, in which the surface 49 Y of the sear becomes disengaged from the retain the 'latter in'place.

trigger head 46, and is free to move upwardly into position to catch the actuator as it is thrown rearwardly, and to retain it in cocked position. Therefore, in order to again fire the gun, it is necessary to fully release the trigger and to pull it anew.y A small spring 45", is so positioned as to force the trigger head upwardly and to return the trigger to operating position, with the head 46 engaging with surface 49 of the sear. The slot 45c of the trigger allows sufficient longitudinal movement of the trigger arm 45, on the pivot pin45, to compensate for the corresponding longitudinal movement of the sear 44.

When it is desired to allow the gun to function as a repeating rifle, the stop 51' provided in the trigger guard 5, is pushed upwardly by the linger of the operator out of engaging position with the trigger, to the osition shown in Figure 2. In this position the trigger may be retracted to its rearmost position, so that the front end of the trigger head 46 engages with the-'surface 48 of the sear and holds thev sear out of the path of thel actuator, so long as the trigger is held in' retracted position. When the trigger is released from retracted position, a suitable spring 51a carried by the stop 51, automatically returns the stop to its normal position, so that the rifle is con-v verted into condition for firing single shots only. It will therefore be seen that the operator can continue the repeated ring of the rifle until the `trigger is released, at which instant the sear will again be forced upwardly in position to catch the actuator and to stop the firing of the gun. 4.

The trigger frame also carriers a magazine locking arm 52, pivoted on pin 53, and having a locking linger 54 adapted to en.- gage in a suitable catch on the magazine to A second locking finger 55 on said arm 52, is adapted to engage a grooved portion 12c on the as- -sembly bolt 12,'to lock the same against endwise movement. The spring 46. which serves to operate the Sear, also maintains the locking arm 52 in locked position. Whenever it is desired either to take out the magazine 9, or to extract the lockinfr bolt 12` the locking arm 52 may be released by manipulating a linger piece 52a, preferably located within the trigger guard.

l The locking bolt 12 not only serves to retain the receiver in locked position onl the stock bracket, as has been before described, but it is also provided with a cam portion 12c which is so constructed 'as-to engage a notch 56 in the bottom face' of the actuator,

`when an indicating arm 57 carried by the bolt, is moved to safe position, as shown. This notch is so positioned that it cannot be engaged by the cam 1 2c unless the actuator is in the furthest forward position, as shown in Figure 2, in which position the liring pin must extend beyond the vface of the breech bolt. With such a construction, the actuator cannot be locked unless the firing chamber is empty. A series of markings` such as: take-down, safe, and ready, or similar markings may be provided on the outside of the rifle as'indicated in Figures 17 and 20 to show the three positions to which the locking bolt is adapted to be turned, as desired,

The opration of the rifle is as follows: The mechanism is cocked by drawing the finger piece 23d rearwardly to 'al cocked position, as shown in Figure l, with the actuator 23 under compression of the spring 24, but retained by the sear 44 .in a rearward position in the receiver. As the trigger is pulled the sear is released and the actuator and bolt move forwardly, with the guide lug 29 of the bolt moving in the longitudinal groove in the receiver, which construction Aholds the actuator and bolt head 22a spaced apart because ofthe cam action between the lugs 25, 25 on the bolt and the camways 26, 26 on theactuator. As the bolt moves forward, a projection 58, on the bolt face engages the rear end of the cartridge 10 in the magazine and forces the cartridge forward out of theV magazine and, guided by the scoop 20, adjacent the mouth of the firing chamber, the cartridge is forced upwardly and into the firing chamber by the breech bolt. As the breech bolt approaches the forward end. of the receiver, the guide fin 2f) 'hs *le offet "f'tin l in t e lonfritudinal grooveV 30, whichfrees the bolt'for rotation in a clock-wise direction. The lugs 25 25 on the bolt are now free to be rotated in the cams 26, 26 so as to bring the locking lugs 27, 27 into locking engagement with the recesses 28, 28 on the receiver, thereby firmly locking the bolt and confining the cartridge in the firino` chamber. The actuator approaches the bdlt head 22b while the bolt is being rotated, and the camways primer of the cartridge in the firing chamneoaeaa ber. Owing to the construction of the dring chamber as has been described, the

lcase rearwardly against the face of' the breech bolt. As has been above described, a limited rearward movement of the cartridge is permissible, provided it 'does lnot exceed 015 of an inch. The construction ,ofV the firing pin is such that: it engages withv the primer and, as the cartridge is thrown rearwardly, the force of this movement is transmitted rearwardly through the ring pin to the actuator. The rearward movement of the cartridge ischecked by the face.

of the locked breech bolt, but vthe primer 10 of the cartridge is still under great pressure caused by the'generation of gases inthe ring chamber, which pressure is transmitted through the primer Vhole of the car'- tridge to such a degree as to -force the primer rearwardly from .its normal position on the" cartridge, as shown in Figure 2. This rearward movement of the vprimeris there. fore a continuing force, acting onthe actuator through the ring pin, tending to ac-o celerate the actuator in a rearward direction. After the actuator has moved rearwardly a short distanoathe lugs25, 25 are rotated in the camways 26,. 26 tounlock the bolt. As the bolt is released,'there is stillav considerable amountof pressure in the firing chamber, which serves toA blow the cartridge out of itsgpositicn in the firing chamber, without however, having suiiicient pressure to damage the cartridge case as it is expelled therefrom. The expended cartridge case lis held in the recess 37 of the breech bolt by means of the extractor 36 during the rearward movement ofthe'bolt until the ejector 40, ixed on the trigger mechanism casing 41, comes into Contact with the rear edge ofthe cartridge casing as shown 'in Figure 11, and flips the expended cartridge out of the receiver. The actuator and bolt continue their rearward movement, storing up suiicient energy' in the spring 24 to return the actuator and bolt to locked and firing position. In single fire work the actuator-is caugl t by the sear i4 dnringvits rear-' 'ward moveldent, and retained in. cocked position'as in Figure 1 ready lto be red again.

rlhe automatic repeating action of theJ rifle is the same as above described except that the stop 51 is raised to permit the trigger 45 to depress the Sear 4d out of the path 'of the actuator, in'which cas'e the automatic action ofthe gun will continue until the magazine is exhausted, or the trigger is released so as to bring the sear back into position for engagement by the actuator.

The operation of disassemblingthe rifle is as follows: if there are any cartridges in the magazine, vit is preferable, first, to manually withdraw the cartridge magazine 9 after releasing the magazine lock 54. The locking bolt 12 is then turned to the take-- down position, as shown in Figure 20, and the cam 12c will be disengaged with the notch 11a on the receiver, thereby permitting the receiver and Vbarrel to be pushed forwardly'on the stock bracket to disengage the lugs 16 and 17A on the stock bracket. The receiver, barrel, and reciprocating breech mechanism can then be withdrawn from the stock bracket. The actuator and breech bolt will normally be retained in the receiver by means of the spring 24, which tends to hold them' in locked relation at the front end of the receiver,but by pushing back the finger pieceA 23d suciently to unlock the bolt, Ythe actuator, bolt and spring may be adroppedout of the receiver for inspection -j or cleaning, if-desired. As the guide fin 29 is no longer held in the groove 30v of the receiver, the lugs 25, 25 on the breech bolt may nowv be rotated out of the open ends of camways 26, 26 s'o that the breech bolt is readily withdrawn from the actuator. The extractor 36 and the firing pin 32 ma be removed from` the breech bolt, if desired, by removing 'the retaining 1 ring 35 which is preferably retained in place in the breech bolt by a pressit, so that it may be'ejected therefrom by forcing'the firing pin against its rear face. Therefore, when the entire breech mechanism is disassembled,'it comprises but six (6 parts, namely: actuator, spring,breechbo t, ring pin, extractor and retaining ring. The assembly of these'parts is equally simple, the only care. necessitated being that of insertingthe breech bolt in the actuator before placing the actuator in the receiver, and then insuring that the guide fin 29 is seated in the longitudinal groove 30,50 that the lugs 25, 25 on the breech bolt cannot be rotated out of the open ends of the camways 26, 26 on the actuator.

The, disassembly of the trigger mechanism from. the stock bracket is equally simple .da has been described, the locking bolt 12 is rotated so as to allow the receiver to be pushed forward and disengaged from. the stock bracket'. The cam 12, which serves as a lock for the actuator, normally extends upwardly into thereceiver-'so that the bolt 12 cannot be withdrawn, or accidentally fall out of the gun as long as the receiver is in place on the stock bracket. However, after the receiver has',been removed the stock bracket, as above described, the

from

locking bolt 12 may be withdrawn by manipulating the locking arm 52 which disengages the locking finger 55 from the groove 12e on the locking bolt. When the locking bolt has been thus disengaged and withdrawn from the stock bracket, the entire trigger mechanism may be withdrawn by moving the same forward, out of engagement with the bolt 3 which extends transversely through the trigger mechanism housing, as shown. "l`he trigger mechanism, therefore, may be easily handled, inspected or cleaned as a unit, or if desired to further disassernble the mechanism, this is easily accomplished by pushing out the scar pivot pin 44", `the trigger pivot'pin 45, and the locking arin pivot pin 53 which normally are retained 1n the trigger frame between the walls of the stock bracket but are free to be withdrawn from the trigger frame when the trigger mechanism isnot confined in the stock brackct. Wlien the trigger mechanism is fully disassembled, it comprises nine (9) parts, namely: sear 44, scar spring 4G, trigger 45, trigger 'spring 45", locking arm 52, pivot vpins 44h, 45a and 5?), and the trigger frame V4l. It will, therefore, be observed that the entire `gun can be disassembled for the purpose ofcleaning, repairs, replacement or transportation, in a minimum of time, and in reassembling, the parts are so few and simple in construction that they are easily understood and replaced by even an unskilled operator. t may be taken down, that is, separated 1nto two major parts by dismounting the receiver from the stock bracket and yet the breech mechanism will be retained iii the receiver and the trigger mechanism will be retained in the stock bracket sotliat none of 'the moving parts will drop out of their respective positions unless positively disengaged and removed by the operator.

It will be observed that the entire mass of the breech mechanism reciprocates substantially on aline with the axis of the rifle barrel, and that the' locking action is by retationvon this axis, instead of any movement of parts transverse to the said axis. This 4feature has been' found to be a determining factor in the accuracy of firing, for it has been demonstrated with automatic rifies having any substantial part of the actuating mechanism moving either transverse` ly of the barrel axis, or even parallel to the axis, that such movement invariably tends to affect the accuracy of firing b v throwing the piece out of predetermined alignment with the target when the gun is fired. In .the present construction, all movements o-f the breech mechanism are directly in line with and on the axis of the barrel, and therefore much greater accuracy is afforded than with other types of construction above mentioned.

As ordinarily constructed, the primers of Furthermore, the riie standard cartridges are provided with com-- made the striking face 32a of the firing pinwith a concave surface which substantially conforms with the normally convex head of a primer, as shown in Fig. 11. The striking point B2b is sufficiently raised to detonate the primer, but as 'the primer is thrown rearwardly the entire rear face of the primer contacts with the striking face of the firing pin in such a manner as to prevent any considerable distortion of the primer, and a consequent loss of power which would be caused by such distortion. It will be remembered that the successful operation of the automatic mechanism depends upon the impulse imparted to the firing pin acting through a very short distance, and for this reason it is preferable to provide the c'onstruction of tiring pin herein described in order to utilize the maximum of power imparted from the limited rearward movement ofthe cartridge, in the manner described.

Having thus fully described my invention what I claim as new and desire to secure by Letters'latent is:

l. The method of operating an automatic gun provided with reciprocating firing mechanism, which consists in so confining a cartridge in the firing chamber as to allow a limited rearward longitudinal movement thereof, exploding the cartridge, and utilizand the rearward movement of. the primer relative to the shell to return the said mechanism to operative position.

2. The method of operating an automatic gun provided with reciprocating firing mechanism normally under the influence of power tending to move it toward the firing chamber, which consists in communicating to said firing mechanism the combined forces of a rearward movement of a cartridge primer relative to its shell and ofv ing the said rearward movement of the shell Y i'io machine gun provided with a reciprocating actuator, which consists in confining a cartridge inthe firing chamber, closing the end of the ring chamber, exploding the cartridge while it is spaced from the closed end rcoacaa of said Chamber, utilizing a rearward movement of the exploded cartridge, vand of the exploded primer, relative to the shell to drive the actuator rearwardly, and then opening the end of the firing chamber and withdrawing the exploded cartridge before the actuator has reached the limit of its rearward movement..

5. The method of operating an automatic machine gun provided with a reciprocating actuator, which consists in confining a cartridge in the firing chamber, closing the end of the firing chamber, moving the cartridge away from the closed end of said chamber, exploding the cartridge while it is spaced from the closed end of said chamber, utilizing a rearward movement of the exploded cartridge, and of the exploded primer, relative to the shell to drive the actuator rearwardly, and then .opening the end of the firing chamber and withdrawing the'exploded cartridge before the actuator has reached the limit of its rearward movement.

6. The method of operating an automatic machine gun provided with a reciprocating actuator, which consists in coniining a cartridge in the firing chamber, closing the end of the firing chamber, exploding the cartridge while it is spaced from the end of said chamber, utilizing a rearward movement of the exploded cartridge and a further rearward movement of the primer thereof relative' to the shell todrive the actuator rearwardly, and then opening the end of the firing chamber and withdrawing the exploded cartridge before the actuator has reached the limit of its rearward movement.y

7 rl`he method of operating` an automatic machine gun provided with a reciprocating actuator, which consists in confining a cartridge in the tiring chamber, closing the end of the'firing chamber, moving the cartridge away from the closed end of said chamber, exploding the cartridge while it is spaced from the end of said chamber, utilizing a rearward movement of the exploded cartridge and a further rearward movement of the primer thereof relative to the shell to drive .the actuator rearwardly, and then opening the end of the firing chamber and withdrawing the exploded cartridge before the actuator has reached the limit of its rearward movement.

8. The method of operating an automatic machine gun provided `with a reciprocating actuator, which consists in causing the forward reciprocation of the actuator vto confine a cartridge inthe firing chamber, closing the end of the chamber, exploding the car` tridge while it is spaced from the closed end, utilizingthe resultant rearward move- -ment of the exploded cartridge to drive the actuator rearwardly, causing the actuator, in its rearward movement, to open the firing chamber and withdraw the exploded carment of the exploded cartridge and a further rearward movement of the primer thereof relative to the shell to drive the actuator rearwardly, causing the actuator, in its rearward movement, to open the firing chamber and withdraw the exploded cartridge, and expelling the exploded cartridge from the 10. The method of operating an automatic machinev gun which consists in deriving energy from 'a movement of an exploded cartridge, and a further rearward movement of an exploded primer relative to its shell confined in the ring chamber.

11. A machine gun comprising automatic reciprocating mechanism operated by power derived from a limited longitudinal movement of the exploded cartridge, and a further limited movement of the exploded primer relative to the shell while the shell is confined inthe ring chamber.

12. A machine gun comprising automatic mechanism operated by power derived from a combination of (zo-acting movements caused by the explosion of a cartridge, including a limited longitudinal movement of the cartridge shell while confined in the firing chamber, and a limited relative movement between the primer and the cartridgeshell.

13. A. machine gun comprising automatic i mechanism operated by power derived from a combination of co-acting movements caused by the explosion of a cartridge primer and of the subsequent explosion of a cartridge, including a limited longitudinali movement of the primer relative to the shell and of a similar movement of the cartridge shell while confined in the firing chamber, and a rearward movement of Asaid shell after the same becomes chamber. Y

1.4. A. machine gun comprising automatic mechanism operated by power derived from a combination of co-acting movements caused by the explosion of a cartridge primer and of the subsequent explosion of a cartridge, including a longitudinal movement of a part of said mechanism mounted for individual rearward movement under impulse of the recoil of the gun, and a limited longitudinal movement of the cartridge shell while confined in the firingv chamber, and a further longitudinal movement of the primer relative to the shell.

15. A machine gun comprising automatic partially released `from said Y mechanism operated by power derived from acombination' ot c'o-acting movements caused by the explosion ofa cartridge, including alongitudinal movement of a part of said mechanism. mounted for individual movement under impulse of the recoil of the gun, a limited longitudinal movement of the cartridge shell while confined in the irin chamber, and a further limited movement o the primer in Vrelation to said shell.

16. A machine gun comprising automatic mechanism operated by power derived from a combination of yco-acting movements caused by the explosion'of a cartridge, in-

cluding a limited longitudinal movement of the cartridge shell while confined in the firing chamber, a further limited movement of the primer relative to said shell and a fun ther movement of said shell after the same `gas become unconned in said tiring cham- 17. A machine gun comprising automatic i mechanism operated by power derived from a combination of co-acting movements caused by the explosion of a cartridge prim-` er and of the subsequent explosion of a cartridge, including a longitudinal movement of a part of said mechanism mounted` for individual rearward movement under impulse of the recoil of the gun, a limited rearward movement of the cartridge shell while confined inthe ring chamber, a rearward movement of the exploded primer relative to the shell, and a further rearward movement of said shell after the same has become partially unconfined in said firing chamber.

18. A machine gun comprising automatic mechanism operated by power derived `from a combination 'of co-acting movements caused by the explosion of a cartridge, including a longitudinal :movement of aart of said mechanism, ymounted for indivi ual rearward movement under impulse of the recoil of the gun, a limited lon itudinal movement of the cartridge shell w ile confined in the tiring chamber, a further limited movement of the primer in'relation to said shell, and a further movement of said shell of firing, vwhile the cartridge is completely forward, and a ring element extending through said member.

21. .A machine gun of the character de- -ing t ex lbo incassa scribed provided with a Vfiring chamber having a rear retaining memberspaced from the cartridge' confined thereby during thein'- stant of tiring, while the cartridge is completel forward, and a firing element extendliirough said closure and reciprocable mechanism adapted for engagement with said element to explode the cartridge.

22. In an automatic machine gun, in combination, a breech bolt adapted to be locked in a forward position, a firing chamber so constructed as to afford a limited longitudinal movement of the cartridge in said firing chamber while the bolt is in locked osition, and means to receive energy from said'limited movement of the exploded cartridge, and from a movement of the exploded vprimer relative tothe cartridge shell, to operate the mechanism of the gun. i v

23. In an automatic machine gun, in combination, a breech bolt ada ted to be locked in a forward position, a ring chamber so constructed as to aliord a limited longituf dinal movement of a cartridge in said chamber, while the bolt is in locked position, means affordin a further limited movement between the exp oded cartridge and the primer in relation to said cartridge while the bolt is in locked position, and means to receive energy from the movement of said exploded cartridge and primer to operate the mechanism of the gun.

24. A machine gun comprising a breech bolt having reciprocating action and adapt# ed to be locked 1n a forward position a f ing chamber so constructed as to adord Ya limited longitudinal movement of .a cartridge in said firing chamber, while the bolt is in locked position, an actuator, means in:

contact with said cartridge and its primer, adapted for throwing said actuator rearwardly u on .explosion of the cartridge, to

unlock sald bolt, and a spring for returning' said actuator.

`25. A machine gun comprising a. breech bolt adapted to be locked 1n a forward position, a firing chamber so constructed as to permit a limited rearward movement of a cartridge therein, a' ,firing pin movably mounted-in said breech bolt and arranged to en age the primer of and explode said cartri ge, and permitting a further rear` ward movement 'of said primer in relation to said cartridge an-agtuator adapted to be thrown rearwardly by said firing pin upon plosion of the. cartridge to unlock said t, and a spring 26. An automatlc gun comprising in com` bination with a reciprocating actuator and a firing chamber a bolt carried by the actu'f ator and adapted to be locked in' sition atl the rear end of' the firing cham r andto' operate as a closure'spaced fromv the 'con-Y to 'return said actuator.'

tained cartridge after the latter has been projected to the limit of its forward moveaeoaeea ment, means carriedby the bolt for tiring the cartridge under impact of the actuator, and means carried by the actuator and bolt for unlocking the bolt after the cartridge is tired.

27. An automatic gun comprising a tiring chamber, a reciprocating actuator, a breech bolt carried thereby, means carried by the actuator' and bolt for locking the bolt in position to close the rear end of the tiring chamber but spaced from the contained cartridge after the latter has been projected to the limit of its forward movement, and a tiring element carried by said bolt and operable under impact of the actuator.

2,8. In an automatic gun provided with a tiring chamber, a reciprocating actuator, and a breech bolt carried thereby, meansl carried by the actuator and breech bolt whereby the forward movement of the former will lock the latter in position to close thetiring chamber, but spaced from the contained cartridge after the latter has been projected to the limit of its forward movement, and whereby the actuator may move rearwardly and, at a certain point in its rearward movement, will operate to unlock the breech bolt, and means carried by the bolt for exploding the cartridge under impact of the actuator.

29. An automatic gun mechanism comprising in combination a bolt forcontining the cartridge in the firing chamber, said bolt leaving the cartridge free to move, a lock for said bolt, and a reciprocatory actuator adapted to move rearwardly after the tiring of the cartridge, and. to thereafter release said bolt. f

30. lin an automatic machine gun in comi bination a receiver, a reciprocatory actuator,

. tridge in the tiring chamber, but leaving thev cartridge free to move a limited distance in 'a breech bolt having rotatable and longitudinal movement, cam connections between said actuator and breech bolt, locking members in said receiver for locking the bolt to con? fine a cartridge in the tiring chamber, but leaving the cartridge free to move a limited distance in said firing chamber when the bolt is in locked position, and a tiring pin movably mounted in said bolt and engaged by the actuator to move the cartridge awayy from the breech bolt.

3l. In an automatic `machine gun in combination a reciprocatory actuator, a breech bolt adapted to be locked to confine a carsaid ring chamber when the bolt is in locked position, a firing pin move-bly mounted in said bolt and engaged by the actuator to move the cartridge away from the breech bolt, todetonate the primer, and to throw the actuator rearwardly, and means carried by the actuator for unlocking the bolt after the cartridge is fired and before the actuator has completed its rearward movement.

32. vAn automatic machine gun provided.

with a receiver, a reciprocatory f actuator mounted therein, a breech bolt-carried by the actuatorand having longitudinal and rotative movement therein, said bolt being adapted to so confine a cartridge as to per-T mit a limited longitudinal movement thereof, and means carried by the receiver for guiding the actuator in its reciprocationsand for co-operatingtherewith in the rotative movements of lsaid bolt.

33. An automatic machine gun provided with a receiver, a reciprocatory actuator mounted therein, a breech bolt carried by the actuator and rotatable therein, and adapted to confine a cartridge, while permitting a limited longitudinal movement of the latter, a iin on the bolt, means carried by the receiver for guiding said iin, and means on the bolt and actuator for rotating said bolt.

34. An automatic machine gun provided with a receiver and aiiringchamber, a reciprocatory` actuator mounted in said receiver, a breech bolt carried by said receiver and rotatable therein, saidbolt being adapted to confine a cartridge in said chamber while permitting a limited rearward movement thereof, and co-operating means mounted on the bolt, the actuator and the receiver adapted upon forward reciprocation of the actuator to rotate said bolt and to tiring chamber.

35. An automaticmachine gun provided with a receiver and a firing chamber, a reciprocatory actuator mounted in. said receiver, a breech bolt carried by said receiver and rotatable therein, said bolt being adapted toconiine a cartridge in said chamberwhile permitting a limited rearward movement thereof, and co-operating means mounted on the bolt, the actuator and the receiver, adapted upon forward reciprocation of the actuator to rotate said holt and to lock it in position to close the rear end of the tiring chamber, said means on the bolt and actuator also operating to unlock the bolt and open the firing chamber, upon rearward reciprocation of the actuator.

36. A machine gun comprising automatic mechanism operated by power derived from a combination of co-acting movements caused by the explosion of a cartridge, including a limited longitudinal movement of .the cartridge shell while confined in the ring chamber, a further limited movementof the primer'relative to said shell, andl a further movement of said shell after the same hasbeen unconined in said ring chamber, said means also operating to hold the bolt locked during a relatively short rearward reciprocation-of the actuator, but operating to unlock the bolt and open the firing chainber upon further rearward reciprocation.

' 37. A machine gunprovided with tiring mechanism, a magazine, and alocking bolt,

, lock it'in position to close the rear end of the and also provided with aplockin arm enand provided with Ban es'preventing unde 'gaging 'sald magazine and hol 'ng it in sired movement of sai spring.

operative position, said arm carrying a porn 39. In a device of the class described a tion normally preventing retraction of said firing pin provided with a strikingr point 5 lockin bolt. and a surface surrounding said pomt and 15 Y 38. n automatic machine gun provided conforming substantially'with the shape ofwith a. receiver containing automatically a primer t be detonated. operating breech mechanism, a spring for In testimony-whereof I aix my signature.

actuatin said mechanism, and a stock 10 bracket etachably connected to said receiver JOHN C. GARAND.

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