US2093705A

US2093705A - Automatic firearm

Info

Publication number: US2093705A
Application number: US711846A
Authority: US
Inventors: Marriner A Browning
Original assignee: J M & M S Browning Co
Current assignee: J M & M S Browning Co
Priority date: 1934-02-19
Filing date: 1934-02-19
Publication date: 1937-09-21
Anticipated expiration: 1954-09-21

Description

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Sept. 21, 1937. M. A. BROWNING AUTMATIGFIREARM Filed Feb. 19, 1934 4 Sheets-Sheet 3 .fm/@n Dz" MarrfhEfE n @www Sept. 2l, 1937. M. A. BROWNING AUTOMATIC FIREARM Filed Feb. 19, 1934 4 Sheets-Sheet 4 Lm/51715 DF Marzi/7er @MM Patented Sept. 21, 1937 I PATENT OFFICE AUTOMATIC FIREARM Marriner A. Browning, Ogden, Utah, assignor to J. M. & M. S. Browning Company, Ogden, Utah, a corporation of Utah The general object of the present invention is to provide an automatic firearm or machine gun which is` simple in construction, reliable in operation, of light weight and capable of sustained 5 operation without excessive heating. A gun embodying the invention is of the gas operated type, the barrel being normally rigidly connected with the breech casing.

In accordance with the invention the cartridge l feed channel is below the barrel, and the cartridges arefed by means of a slide positioned below the feed channel and above the gas actuated operating slide.

Further in accordance with the invention I 15 provide an improved means for transferring the cartridges from the feed channel to the chamber ofthe barrel and improved means for ejecting the empty shells.

In the accompanying drawings I have shown 2o one embodiment of the invention, but it will be understood that the drawings are for illustrative purposes only and are not to be relied upon as limiting or defining the scope of the invention, the claims forming a part of this specification 25 being relied upon 4for that purpose.

0f the drawings:

Fig. 1 is a side view of a firearm embodying the invention.

Fig. 2 is an enlarged fragmentary view of the 30 rear portion of the firearm, this View being partly a side view and partly a longitudinal sectional View.

Fig. 3 is a view similar to Fig. 2, but showing the parts in different relative positions.

35 Fig. 4 is an enlarged fragmentary View of the front end of the firearm, this view being partly a side view and partly a longitudinal sectional view.

Fig. 5 is a view similar to Fig. 4, but showing 40 the parts in different relative positions.

Fig. 6 is a fragmentary perspective View of the v rear portion of the barrel.

Fig. 7 is a transverse sectional view taken along the line 'i-i of Fig. 4.

45 Fig. 8 is an enlarged sectional View of the front buffer means for the operating slide.

Fig. 9 is a transverse sectional view taken along the line 9 9 of Fig. 2. y

Fig. 10 is a perspective view showing the ex' 50 tractor and associated parts.

Fig. 11 is an enlarged fragmentary horizontal sectional view taken along the line ll-il of Fig. 1.

Fig. 12 is a view similar to Fig. 11, but showing 55 the parts in different relative positions.

Fig.' 13 is a plan view of the operating slide,

'together with a part of the piston rod.

Fig. 14 is a side view of the parts shown in Fig. 13.

Fig. 15 is a perspective view of the feed slide. 5

Fig. 16is a transverse sectional view taken along the line iG--IE of Fig. 12.

Fig. 17 is a view taken along the line i'i-H of Fig. 11 and showing in detail the extractor and the cam mechanism which operates it. In this 10 view the extractor, the pressure lever for the extractor and the cam mechanism are shown in full lines and all other parts are shown in dotand-dash lines.

Figs. 18, 19 and 20 are views similar to Fig. 15 17, but showing the parts in different relative positions.

Referring to the drawings, I represents as an entirety the main breech casing which is general- 1y rectangular in section as lshown in Fig. 9. As 20 shown the casing is formed from a single piece of steel although I do not necessarily limit myself to this integral construction. The portion I of the casing is formed to receive the rear end of a barrel 2. Behind the portion Ia are two main side walls ib, ib connected at the rear by an integral top wall 1. An opening ld is provided in .the top wall, .which opening is normally closed by a pivoted cover 3 held by a releasable latch 4. The bottom of the casing is normally closed by separate plates 5 and 5a. The rear of the casing is normally closed by a plate 6 flanged at its sides and having ribs (not shown) adapted to enter grooves 1, l (see Fig. 11) formed in the side walls Ib, lb. A suitable latch (not shown) serves to normally hold the end plate 6 in place. Carried by the plate 6 at opposite sides thereof are two brackets 8, 8 carrying

handles

9, 9.

The vbarrel 2 is preferably detachably connected with the casing and has a rear cylindrical portion 2a which fits a cylindrical hole in the portion Ia of the casing. The rear end of the barrel is provided at I with interrupted external threads adapted to engage similar internal threads formed in the casing. When the barrel is in the position shown in Figs. 2 and 3 it is firmly heldin place by the threads. It can be released by being turned through a quarter turn in the clockwise direction. The barrel is normally held in its locked position by means of a pin Il held by a spring l2. The 50 rear end of the spring is T-shaped and fits a T-shaped groove I3l in the top of the casing, and a screw IS normally serves to prevent the spring from moving rearward out of the T-shaped slot. The pin H can be withdrawn from the 1 such: as the h'ead of `ai cartridge and then the 1' barrel lcan be turned in the: clockwise direction 1 f to disengage the .interruptedthreadsat l0.' This. 1 permits'the barrel to be ldrawn out in the forward' direction ls'Jimlte'd nyal shoulder 1|.'| .onf the .tube L which engages a shoulder |8011 fthe; casinlg-1y At 1 f its forwardend1r the tube connected with and direction. In order to ravoid the necessity 1for= f rusingl a toolltoreplaoethe barrehthebarrel is 1' 1 1 `fprovided asshown ;in1Flgs.16 and 16 with a lon- 1: 1 gitudinal groove positioned to receive fand pro The groot/e151l 'has a beveled surface' |15*Il adjacent rits `forward :1 end, which surface serves toj cam the pin 1|| `out'- 1 I' wardwhen the barrel `is moved ink the 'counter-l f clockwise direction into locking position. iAs 'soon as Alocking position isr reached thepin .i l 1 snaps; A; i into the'hole in the barrel,1 thus firmly locking it.

vide 1 clearance for ithe` pinr ||.1

' l *The'bar'rel2 is'preferably'providedwitha series' barreland-r substituting another.y -1 1 1 1 1 1 1 The casingl 1| iis' provided lwith Een integral ein` 11 tension ld which extends forward underneath the barrel. i".l'hisextension:is hollow and it. serves to 1 engage; and :retain a :piston :tuble Iii.. The tube' i6' is preferably. slidable :longitudinally with1 rez-1 l f spect to the casing,y andmovement-inthe forward 1 supported by the' barrel. Preferably the. tube fis f providedjatthe top thereof with"aTIT-'shapedpiro-fy 1 Vjection .|9`whch "fits: a sir'nilarly shaped T-.slot '1 formed ini a band :20 secured to the barrel.' jWith. j the parts engaged as .shown in Figs. 14 1and171 the 1 1 .tube fis heidi in ri-'gid relationship to the barrel.' 1 butby moving the tuberearwardgit,y isdisengaged f ytron'ithe Abari-elses shown in li'ig.` V5, thusle'aving 1 1 thefbarrel Ii-eef to fbe Atui-nettso .that it may be 1 disengaged from the casingln =the manner already explained.

The tube |16 is normally heldin its forward en-f gaged position by means of two .links 2| and 22 which are pivotally connected with each other by a pin 23. Preferably the link 2| is U-shaped in'cross section so as to partly surround and enclose the link 22. The link 2| is pivoted to the front end of the portion |d ofthe casing by means of a removable pin 24, and the link 22 is pivoted to the tube I6 by means of a pin 25. A spring 1 pressed latch 26 is provided for holding the link 2| in its upper or normal position. It will be observed that with the parts in the positions shown in Fig. 4 the tube I8 is held in its forward position, the link 2| substantially enclosing the link 22. When it is desired to move the tube I6 in the rearward direction the link 2| is disengaged from the latch 26 and the link is moved 4downward to the position shown in Fig. 5, thus drawing the tube rearward and disengaging the projection I9 from the T-slot in the band 20.

Longitudinally movable along the bottom of the main casingis an operating slide 21, this slide being connected with a piston rod 28 and a piston 29 positioned within the piston tube I6. Preferably the piston 29 is formed integrally with the vrod and consists of one or more annular anges thereon. A cylinder 30 is provided in the forward end of the tube I6, being held in place by threads, and the piston 29 accurately fits the said cylinder. A series of registering gas holes connect the bore of the barrel '2 with the interior of the cylinder 30 in order that a portion of the gases For returning the slide in the .forward 1 after having beenzmovedrearward :by the .piston 1 that nagllyr through a of explosion may .enter the cylinderand .actiupoll the-'piston 2s toforce it rearward 1' and piston rod, there is provided an action Aspring :3| supported upon and guidedrby; a rod 32.y :Pref-i 1 -1 l l erably. the spring 'and ro1d13| and .312 extend into 1 l 1 `ahcllow :buffer 3.31 carried Aby the rearplate ,6.1 1

l34 ldetachably secured in place inthebuiler.1 The :Thespringatits rearjendfabuts against a head 1. .1.

spring at yits forward end extends into an aper-1 turein-the slide 21 land abuts against a shoulder .1 i

35. .Ahole'36 provides clearancefor the Arod132 1.

when .thesiideis in its rear.position.'1l

1 .When the slide moves: ,forward under one in- 38. A lremovable screw 139 serves to'y hold the; two

i bushings yin place.; It will be'observedthatwhen1 1 1 f 1 lthe slide; 2 linox/es,fcnfwari ltengages the-inner.1 i .1 .1 f i lbushing A38 which isforced'into theouter bush-1 'ing' 31. .1 outer bushingby reason of the 4fact 1 it lis split and is resilientfoers friction which 1 1 'resistsandi stops sthe forward movemcntofl the 1 1 1 slide.: :When the slide againA moves rearward the 1 1 1 inner-bushing: 13B followsituntil limited by the: :1.11 11.

screw139; the' bushing thus; beinggready tobe er1- 1 cased1r bythe slide upon its next-onward move-fi iment. :1.

1 11n ma a.. sans 181.* mais sans, .fag at. j i i; sorbing thev energy ofthe slide at the end of its by the front end portion of the casing which abuts against the shoulder |1 on the tube. In order'to permit limited movement of the tube the link 2| is provided with elongated holes 'for receiving the pivot pin 24. From the foregoing description it willv be observed that the energy of the slide is absorbed in part by the two coacting bushings 31 and 38 and in part by the plunger 40. The plunger serves to return the piston tube I6 to its normal position'as shown in Fig. 4 after it has been moved forward as the result of the blow delivered by the slide.

The plunger 40 not only serves as a buffer to absorb the energy of the slide, but it also serves to permit or cause sharp vibratory movements of the piston tube which tends to break loose any deposits which might otherwise tend to form in the cylinder 30 or on the guide surfaces at I9. With some types of ammunition these deposits become seriously objectionable and the vibratory movement which I have provided assists in preventing the accumulation and adherence of such deposits.

The slide 21 serves to operate the feeding, loading and firing mechanisms of the gun and these mechanisms will now be describedin detail.

Extending transversely through the casing below the rear portion of the barrel is a cartridge feed channel 4| adapted for the reception of a. cartridge belt, such as A. The channel 4| is sufciently wide' at the left hand side of the gun to permit the entry of cartridges, but preferably its width is only slightly greater than the length of forward moi/ement, provisionales :be made for` 1 permitting the1entire; tube |61 to move; longitulifl 1 slightdistance. shown theref is providedr a spring'pressedplunger lil carried the cartridges. At the right hand side the feed channel is much narrower, being onlyv wide enough to permit the exit of the canvas belt which carries the. cartridges. Below the cartridge channel `4| and above the slide 21 are two opposite

transverse ribs

42, 42 which form guiding means for a feed slide 43. The feed slide with its appurtenances is in some respects similar to that disclosed in Patent No.. l,293,021 to John M. Browning.

At the top of -the slide 21 there is provided a cam path which is preferably in the form of a cam groove 44 cut in the top surface of the slide. At least a portion of this groove 44 is inclined with respect to the longitudinal movement of the slide, and as shown the cam path also has a longitudinal rear portion 44a and a longitudinal forward portion 44h. On the bottom of the feed slide 43 there is provided means such as a pin 45 for engaging the cam path or groove 44. The feed slide should be made as light in weight as strength requirements will permit, the object of this being to keep the total mass of the moving parts actuated by the operating slide as rsmall as possible so as to obtain maximum speed of operation and to reduce the total weight of the firearm. By forming the cam groove 44 in the operating slide' and providing the feed slide with the pin 45 the width of the feed slide can be reduced to that necessary for proper feeding of the cartridges. As shown, the feed slide is substantially less in width than the cartridge feed channel 4|. When the slide 21 is in its rearmost position as shown in Fig.` ll the feed slide 43 is at the left hand limit of its movement; and when the operating slide 21 is in its forward position as shown in Fig. l2 thejfeed slide is at the right hand limit of its movement. Thus longitudinal movement of the operating slide 21 serves to cause transverse movement of the feed slide 43. Carried by the feed slide 43 is a plvoted pawl 46 which is adapted to engage the successive cartridges of the belt A to feed the said belt from left to right during the movement Aof the feed slide from left to right. The pawl 46 is provided with a tail piece 46a which underlies and helps to support the cartridge which is engaged. During movement from right to left the pawl 46 passes under the next 'following cartridge and then snaps upward in position to engage it. A pawl 41 carried by the casing serves to prevent outward `movement of the feed belt.

Preferably the slide 21 and the parts associated therewith are removable from the rearm at the rear thereof. To effect such removal it is necessary first to remove the spring 3| and the rod 32 and to then remove the end plate 5 with the parts carried thereby. The slide is then free to be withdrawn in the rearward direction except for the fact that the pin 45 is engaged in the cam vgroove 44. In order to permit the rearward re- 'moval of the cam slide, provision is made to per- -'mit the cam engaging means onthe feed slide,

that is, the pin 45, to be disengaged from the cam path, that is', from the groove 44. ll'his disengagement may be eiected in different ways, but I have shown the groove 44 as having a transversely unobstructed portion or opening 48. During the normal reciprocation of the slide 21 the unobstructed portion or opening 48 does not come into register with the pin 45, but by moving the slide rearward slightly beyond its normal limit ofmovement the opening 48 is brought into register with the pin 45, thus permitting the pin and slide to be moved transversely sufficiently to be disengaged from the cam groove 44. In order to permit this transverse movement the adjacent wall of the casingbelow the feed slide is provided with a notch 48a to provide clearance for the pin 45. With the pin 45 thus disengaged from the cam groove the slide can be readily withdrawn rearward.

Preferably the feed slide 43 is entirely removable from the firearm, being normally held in place solely by reason of the engagement of the pin 45 with the groove 44. So long as the operating slide 21 remains within its normal range of movement the feed slide 43 is held and removal thereof is prevented. However, when the operating slide is moved sufficiently to bring the opening 48 into register with the pin 45 the feed slide can then be entirely removed from the firearm. Y y

The firearm is provided with a reciprocating breechA bolt 49 having lateral guide ribs 49B-, 49a which enter longitudinal'grooves in the side walls -|b, ib of. the casing and thus guide the breech bolt for longitudinal movement. The breech bolt is operated and controlled by mechanism operated by the slide 21, this mechanism being similar 'to that disclosed in Patent No. 1,293,022 to John M. Browning. As shown in Fig. 2 the breech bolt 49 is connected with the slide '21 by means *of two links 50 and 5| pivotally connected with eachother at 52. The link 50 is pivotally connected with the breech bolt at 53 and the link 5| is pivotally connected with the slide at 54. When'the slide 21 is in its rear position asshown in Fig. 2, .the two links 50'and 5| are substantially in alignment and an extension 50B 'on the link 50 engages the top wall ofathe casing to hold the links in the relative positions shown.

When the slide 21 moves forward under the influence of the action spring 3| the two links 50 and 5I and the breech bolt 49 move in unison with it until the breech bolt nearly reaches its forward position, the 'link 50 being then approximately in register with the opening ld in the top wall of the casing. At or about the time that the link comes into register .with the opening the curved portion 5|!b of the link 50 engages two cams 55 projecting inward from the respective side walls Ib, lb of the casing. lIn the drawings only the cam on the left hand side is clearlyslide 21 has continued its forward movement,

thus bringing the link 5| into a substantially upright position. With the parts in the positionk shown and described, the breech bolt is firmly locked in its forward or breeched position and is well adapted to resist the recoil-action incident to firing. Following firing the slide 21 is moved rearward by the action of the gases of explosion in the manner already described, the

link 5| then serving rst to .draw the link 50 downward out .of locking position and then to move the link 50 and also the bolt 49 rearward to the positions shown in Fig. 2.

Referencehas already been made to the fact that the slide 21 can-be removed through the rear oi the casing. It will be understood that 'the breech bolt 49 and the links 50 and 5| are similarly removable, all of these parts being removable as a unit.

A firearm incorporating the present invention is intendedl to be used with cartridges having annular grooves in the heads thereof, andthe front end of the breech bolt is provided with vertical ribs 56, E1 which cooperate to form a vertical groove for receiving and retaining the heads of the cartridges. When the breech bolt is in its forward position as shown in Fig. 3 the head of the cartridge which is in central position in the feed channel 4| is vertically below the groove in the front of the breech bolt. For. withdrawing the cartridge from the feed channel and lifting it into proper relationship to the breech bolt vthere is provided. an extractor 58 shown in detail vin Fig. 10. 'Ihis extractor is provided with a pivot pin 59 which fits a transverse pivot opening in the breech bolt, the extractor thus' moving bodily rearward and forward as the breech bolt moves. The extractor 58 is provided with a transversely extending tooth 60 which is so shaped and positioned as to enter the groove in the cartridge when the breech bolt and the extractor are in their forward positions as shown in Fig. 3. For pressing the forward end of the extractor upward so as to hold the tooth 60 in firm engagement with the cartridge, there is provided a pressurelever 6I pivi oted to the breech bolt and engaging at its forward end with the extractor. A coil spring 62 tends to move the pressure lever 6| in the counter-clockwise direction, thus pressing the forward end of the extractor upward.

A suitable cam mechanism is provided for controlling and guiding the relative movements of the extractor and preferably this mechanism is located at the left side of therearm. For convenience of construction the left side wall Ib is cut away to provide an .opening 63 as shown in Fig. 2 and this opening is covered by a plate 64, shown in Figs. 11 and l2. The cam mechanism to be now described is carried by the plate 84 and projects inward through the opening 6I.

The extractor 58 is provided with a pin 65 which projects toward the left and which serves as a means for controlling the upward and downward movements of the extractor. Preferably this pin is spring pressed outward so as to provide frictional engagement at its end with the surface of the cam plate 64. When the breech bolt moves rearward from the position shown in Fig. 3 the extractor 59 withdraws the cartridge with which it is engaged and the extractor is moved upward by the lever 6|. Thereafter as shown in Fig. 17 the pin 65 engages a cam surface 66 on the plate 64 which forces the pin upward and thus causes continued upward movement of the extractor. Thus the cartridge is moved not only rearward but also upward. Continued rearward movement brings the parts into the relative positions shown in Fig. 2, the pin being retained between two cam walls and the cartridge being lifted nearly to its firing level.

The cam plate 64 carries a pivoted cam member 61 which is normallyspring pressed to the position shown in Figs. 2, 18 and 20. However, the pin 65 in moving rearward passes under the rear portion of the cam member 61 and lifts it as shown in Fig. 1'1. When the parts move forward from the position shown in Fig. 2, the pin 65- iand 3..

movement continues the vcartridge'is pushed into the chamber in the barrel as shown in Figs. 19

When the :cartridge has been sufficiently entered in. the chamber to be retained thereby, .the extractor 58 is withdrawn from, it, the` pin 85 engaging the lcam surface 68 as shown in Fig. 19 and being pushed downward. In order 4to support the rear end of the cartridge and to prevent it from "moving downward with the extractor, there is provided a resiliently held detent 69 pivoted in a slot in' the-bolt 49. This detent is pressed in the forward directionby a spring plunger 10. and it thus snaps under the cartridge to support it. l f

As forward movement continues to the position shown in Fig. 20, the extractor is moved still further downward, the pin 65 being disengaged from the cam members and the extractor being held directly by the ,cam surface 1i. As the extractor reaches the position shown in Fig. 20, which is the same position shown in Fig. 3, the

tooth 60 engages the next cartridge and the parts are in positions for a repetition of the loadingy operationwhich has just been described.

With the parts in the positions shown in Figs. 3 and 20, firing is automatically effected by means to be presently described and the parts again move in the rearward direction. The shell'of the cartridge which has just been red is still held inthe groove in the front face of the bolt and this shellis-drawn vrearwardas the holt moves'rearward. When the new cartridge from the feed channel is moved rearward and upward in the manner already described, it engages the empty shell of the preceding cartridge and moves it upward to the position shown at B in Fig. 9. As shown in Fig. 9 the right hand rib 51 ,forming the cartridge groove extends to the top of the bolt, but the left hand groovev 56 terminates below the top of the groove. When a cartridge has beenmoved to the position indicated at B it is still in engagement with the right hand groove 51, but it is above and out of engagement with the left hand groove 56. At the top of the bolt and .at .the left side thereof there is provided an ejector 12 normally held by a spring 12* in itsrearward position with respect to the bolt as shown in Fig. 12. The ejector 12 is connected to the bolt by means of a stud on the bolt extending through a slot in the ejector. In Aits normal position the ejector is not engaged .by the shell as 'it moves upward to position B, but preferably Athe ejector has a hook portion 1I which is vertically above the shorter rib 56 on the bolt. It will thus be seen that as the shell is moved upward to the position B it is adapted to be engaged partly by 'the upper end of the rib 51 -and partly by the hook portion 12 of the ejector 12. Carried by the casing at the left side thereof is a pin 14 which is in position to engage a stud 15 projecting from the ejector. Just before the ybreech bolt reaches its extreme rearward position the pin 14 engages the stud 15 and moves the ejector relatively forward with respect to the bolt as shown in Fig. 1l, thus throwing the cartridge shell toward the right to the position B' shown in Figs. 2 and 11. An ejection opening 16 is provided Ain the right wall of the casing and the shell is thus thrown out through this ejection opening.

Preferably the pin 14 is carried by a spring 11 secured to the-left side wall of the casing. 'Ihis spring mounting for the pin 14 enables the pin to be withdrawn so as to avoid interference when I have referred to the lifting of the cartridge shell to the position B by the action of the next following cartridge. It is necessary, however, to eject the last cartridge that is to be red, that is, the last cartridge in thecartridge belt, and in order that this last cartridge maybe properly lifted to ejection position I preferably avoid complete dependence upon the next following cartridge as the lifting means. As clearly shown in Fig. l0, a lifter 18 is pivotally mounted on the extractor 58, the said lifter being shaped to fit around the cartridge that is being moved by the extractor and the said lifter having an upper surface 19 adapted to engage the cartridge shell to be lifted and ejected. This lifter cooperates with the next following cartridge, if there be one, to lift the shell to the level B, and if there be no next following cartridge the lifter serves in and of itself to so lift the shell. The lifter 18 is resiliently held and as the extractor moves downward again as shown in Fig. 19 the lifter yields laterally. y v

Mounted in the breech bolt is a firing pin 80 biased in the forward direction by means of a spring 8l. Pivoted on the breech bolt is -a sear 82 adapted to engage a shoulder 83 on the pin as shown in Fig. 2. A spring pressed plunger 84 serves to bias the sear toward its operative position. 'I'he firing pin 80 is provided with a shoulder 85 which is adapted to be engaged by a shoulder 86 on the slide 21. From the description which has already been presented, it will be understood that the slide 21 moves rearward to a greater extent than does the breech bolt 49 and it will, therefore, be evident that in moving from the position shown in Fig. 3 to the position shown in Fig. 2 the shoulder 86 will engage the shoulder 85 to move the Vfiring pin 80 relatively rearward into its cocked position so that it can be engaged and held by the sear 82. As the parts move forward from the position shown in Fig. 2`

to the position shown in Fig. 3 the lower tail portion of the sear 82 is engaged by a shoulder 81 on the slide 21, the sear being thus withdrawn from the firing pin and the firing pin being thus released to move forward under the influence of the spring 8| and to effect firing of the cartridge.

For holding the slide 21 in its rear position as shown in Fig. 2 there is provided .a second sear 88 pivoted to the bottom plate 5. This sear is spring pressed upward and engages a notch 88 in the bottom of the slide. Carried by the rear plate 6 is a manually operable trigger 98 having a tail portion 9| which projects forward through an opening in the plate and is adapted to engage the sear 88. A spring pressed plunger 92 tends to hold the trigger inits rearward inoperative position.

By referring to Fig. 2 it will be observed that when the slide 21 is held by the sear 88 the shoulder 85 on the ring pin is directly engaged by the shoulder 86 on the slide, the ring pin thus being firmly held entirely independently of the sear 82. This makes it impossible for the ringv pin to be accidentally released by Vibration or otherwise while the breech bolt is in its rear position.

,In initially loading the gun in order to start ring it is ordinarily necessary to operate the mechanism of the gun by hand in order to withdraw the first cartridge from the belt and transfer it into the position'shown in Fig. 2. For this purpose there is provided a handle 93l extending through a slot 94 in the left side wall of the casing and fitting a hole 95 in the slide 21. The

slot 94 is enlarged at its rear end and the handle 93 is so formed that it can be removed only when in register with the enlarged rear end of the slot.

From the foregoing description the operation of the gun will be readily understood and only a very brief summary is needed. When the trigger 90 is pressed forward the-sear 88 is disen-- gaged from the slide 21 and the slide moves forward, causing the several parts to assume the positions shown in Fig. 3. When these positions are reached the sear 82 is engaged by the shoulder 81 and is moved, thus releasing the ring pin 80 and causing firing. Thereupon the gases of explosion enter the cylinder 30 and drive the piston 29 rearward, thus moving the slide 21 rearward and causing the various parts of the gun to assume the relative positions shown in Fig. 2. During this rearward movement a new cartridge is extracted from the belt and the shell of the exploded cartridge is ejected in the' Avolley firing may be continuedA so long as ,the

trigger 90 is held and so long as the supply of cartridges in the belt is not exhausted.

What I claim is:

l. 'Ihe combination in an automatic rearm, of a barrel, a breech casing carrying the barrel and having a transverse cartridge feed channel` therein immediately below the rear portion of the barrel, a movable breech bolt inthe casing, a transversely movable cartridge feed slide below the feed channeLan operating slide below the feed slide automatically movable rearward upon ring connected with the breech bolt tol move the same and having at the top thereof a cam path at least a part of which is inclined with respect to the direction of movement and which has a transversely unobstructed portion,

and means lon the bottom of the feedyslide normally engaging the cam path to cause .normal y transverse movements of the feed slide, the last said means being readily separable transversely from the cam path when in register with lthe unobstructed yportion thereof to permit the operating slide to be removed longitudinally from the casing independently of the feed slide.

2. The combination in an automatic rearm, of a barrel, a breech casing carrying the barrel and having a transverse cartridge feed channel therein immediately below the rear portion of the barrel, a movable breech bolt in the casing, a transversely movable cartridge feed slide below the feed channel, a cam path engaging means on the bottom of the feed slide, and an operating slide below the feed slide automatically movable rearward upon firing connected with the breech bolt to move the same and having vat the top thereof a cam pathI which engages the said means on the bottom of the feed slide and atleast a part of which is inclined with respect to the direction of movement of the operating slide so as to cause normal transverse movements of the feed slide, the said cam path serving when the operating slide is lwithin its normal range of movement to retain engagement with the engaging means on the bottom of the feed slide and ,the said cam path being tr svers'ely unobstructed at one end to permit isengagement of the said means therefrom when the operating slide is in an abnormal position.

3. Anautomatic firearm comprising in combination, a barrel, a breech casing carrying the barrel and having a transverse cartridge feed channel-therein immediately below the rear portion of the barrel, a movable breech bolt in the casing, a transversely movable cartridge feed slide below the feed channel and removable transverselyfrom the'casing, a cam path engaging means on the bottom o f the feedslide, and an operating slide below the feed slide automatically movable rearward upon firing con-- unobstructed at one end to permit such removal when the operating slide is in an abnormal lposition.

4. In an automatic firearm, the combinationof a barrel, a breech casing carrying the barrel and having a transverse cartridge feed channel therein below the level of the barrel, a breech bolt in the casing automatically movable rear- 1 from the feed channel and to move each of them upward with its head in the said groove in front of the bolt. and a resiliently held detent on the bolt permitting free upward movement of each cartridge and automatically moving forward under each cartridge to prevent downward movement thereof.

5. The combination in an automatic firearm, of a barrel, a breech casing carrying. the barrel and having a. transverse cartridge feed channel therein below the level of the barrel, a breech bolt in the casing automatically movable rearward upon Afiring and having in the front thereof a vertical groove for. receiving and retaining the heads of the cartridges, an ejector carried by the bolt at a level above the firing position of the cartridges, an extractor movable with the bolt and serving during movements to extract successive cartridges from the feed channel and to move each of them upward into firing position with its head in the said groove in the front of the bolt and also serving to movethe shell of the next preceding cartridge upward into position to be engaged by the ejector, and means acting near the end of the rearward movement of the bolt for causing relative movement of the ejector to disengage the said cartridge shell from the bolt and eject it from the firearm.

6. The combination in an automatic firearm, l

forming a vertical groove for receiving and retaining the heads of the cartridges, an ejector carried by the bolt above the end. of the shorter rib, an extractor movable with the bolt and serving during movements to extract successive cartridges from the feed channel and to move each of them upward into ring position with its head in the said groove in the front of the bolt and also serving to move the shell of the next preceding cartridge upward out of engagement with the shorter rib While retaining engagement th the longer rib, and means acting near the nd of the rearward movement of the Ibolt for relatively moving the ejector and thereby causing it in cooperation with the longer rib to eject the said cartridge shell from the firearm.

7. The combination in an automatic firearm, of

`a barrel, a breech casing carrying the barrel and having. a transverse cartridge feed channel therein below the level of the barrel, a breech bolt in the casing automatically movable rearward upon firing and having at the front thereof twoA rigid vertical ribs of different lengths and heights forming a. vertical groove for receiving and retaining the heads of the cartridges, an ejector carried by the bolt at the top thereof and having a hook portion aboveand in vertical register with the said shorter rib, an extractor movable with the'bolt and serving during movements to extract successive.4 cartridges from the feed channel and to move each of them upward into firing position with its headin the said groove in the front o'f the bolt and also serving to move the shell of the next preceding cartridge upwardout of engagement with the shorter rib and into engagement with the hook portion of the extractor while retaining engagement with the longer -rib, and means acting near the end of the rearward movement of the bolt for relatively moving the ejector and thereby, causing it in cooperation with the longer rib to eject the said cartridge shell from the firearm.

8. In an automatic firearm the combination, of a barrel, a breech casing carrying the barrel and having a transverse cartridge feed channel therein below the level of the barrel, a breech bolt in the casing automatically movable rearward upon firing and having in the front thereof a vertical groove for receiving and retaining the heads of the cartridges, an ejectorV carried by the bolt at a level above the firing position of the cartridges, an extractor movable with the bolt and serving during movements to extract successive cartridges from the feed channel and to move each of them upward into firing. position with its head in the said groove in the front of the bolt, and a lifter carried by the extractor and adapted to engage the shell of the next preceding cartridge to move it upward into position to be engaged by the ejector, and means acting near the end of the rearward movement of the bolt for causing relative movement of the ejector to disengage the said cartridge shell from the bolt and eject it from the firearm.

MARRINER A. BROWNING.