US2388291A - Machine gun - Google Patents

Description

W. B. RUGER MACHINE GUN Nov. 6, .1945.

Filed Aug. 7, 1940 6 Sheets-Sheet l NOV. 6, 3.945. W B, RUGER 2,388,291.

MACHINE GUN Filed Aug.l 7, 1940 6 Sheets-Sheet 2 Nov. 6, E945. w. B. RUGER I 2,383,29 I

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MACHINE GUN Filed Aug. 7, 1940 e sheets-sheet s Patented Nov. 6, 1945 N ETE@ S'ES PATE attain t @FFME MACHINE GUN William B. Ruger, Greensboro, N. C.

Application August 7, 1940, Serial No. 351,727

23 Claims.

In general terms this machine gun is gas oper ated, air cooled and fed by means of the well known fabric o-r metallic belt. By virtue of its unique mechanism this weapon combines re power and mobility to an unusual degree. It is relatively short, light, compact, and possesses clean exterior lines. A large proportion of the total weight of the gun is in the barrel where weight is needed to resist overheating. The entire mechanism is positive in operation; all the parts are extremely rugged and simple to manufacture. In the detailed description which follows, it will be observed that the structure described rnay be considerably altered without departing from the basic invention.

In the drawings:

Fig. 1 is a vertical longitudinal sectional view through the receiver of the gun showing the mechanism in a firing position;

Fig. 2 is a vertical sectional view on the line 2-2 of Fig. 1, omitting, however, the trunnion block, and showing the bolt; in elevation;

Fig. 3 is a perspective View showing the bolt, cartridge feeder and portions of the action slide in the firing position of Fig, 1;

Fig. 4 is a vertical longitudinal sectional View through the receiver ofthe gun showing the action slide and bolt as moved part way to the rear from the position of Fig. 1 and the cartridge feeder moved to the rear and rotated about a. longitudinal axis 30 from the position of Fig. l;

Fig. 5 is a vertical sectional View on the line 5-5 of Fig. 4, showing the bolt in elevation;

Fig. 6 is a perspective view showing the bolt, cartridge-feederand portions of the slide in the positions of Fig. 4;

Fig. '7 is a vertical longitudinal sectional view through the receiver of the gun showing the action slide and bolt as having moved farther to the rear from the position of Fig. 4, and showing the cartridge-feeder in its delivery position after having been rotated a further 60. Fig. '7 is drawn to a smaller scale than Figs. 1 and 4;

Fig. 8 is a vertical sectional view on the line 8--48 of Fig. 7

Fig. 9 is a perspective view showing the bolt, cartridge-feeder and portions of the slide in the positions of Fig. 7

Fig. 10 is a Vertical longitudinal sectional View, through the receiver of the gun, showing the action slide and bolt in their rearmost positions and to the sa-me scale as Fig. '7;

Fig. l1 is a vertical sectional view on the line Il--H of Fig. 10;

.Fig 12 is a perspective view showing the bolt,

cartridge-feeder and portions of the slide in the positions of Fig. 10;

Fig. 13 is a, vertical sectional view on the line I3-I3 of Fig. 4;

Fig. 14 is a vertical sectional view on the line lli-I4 of Fig. 1;

' Fig. 15 is a vertical sectional view on the line I5-I5 of Fig. 4;

Fig. 16 is a vertical sectional view on the line lB-IG of Fig. 4;

Fig. 17 is a vertical sectional view on the line I'I-II of Fig. 1;

Fig. 18 is a vertical sectional view on the line |8-I8 of Fig. 1;

Fig. 19 is a side elevation of the entire gun;

Fig. 20 is an extension of Fig. 10, showing certain parts which are located within the gas tube of the gun;

Fig- 21 is an end View, and 22 is an elevation of the locking pin which connects the bclt and the action slide; and

Fig, 23 is a fragmentary sectional View on the line 23--23 of Fig. 19 showing the cam surface at the rear of the ejection port which cooperates with the locking pin of Figs. 21 and 22.

With reference to the drawings, the frame of the gun consists of several rigidly assembled parts; the receiver casing i, the trunnion block 2 and the cylinder tube 3. The cylinder tube is Welded to the nut 4, which is tightly threaded into the trunnion block, and the receiver casing is held to the trunnion block by means of rivets or any other suitable means. The receiver casing is a length of steel tubing, seamless or otherwise, having the cross sectional shape shown in Figs. 13 to 18. The trunnion block has a similar cross-sectional shape, and is preferably of such dimensions that it will have a drive fit in the forward end of receiver casing i. The various ports for the entrance and exit of the belt and for the ejection of empty shells are cut through both the vtrunnion block and receiver casing to register with each other, as though these two members Ywere formed from a single solid piece.r

Theupper part of the trunnion block 2 is bored out lengthwise'to receive the cylindrical bolt i0 and the barrel 5. Threads, or any suitable means are provided to lock the barrel to the trunnion block, and the annular groove 6, entering into the slot 'l (Figs. 10, 17 and 18) and the ejection port 8, provides in conjunction with the lugs 9 on the bolt l0 a breech locking system which is old and wellvunderstood in the art.' The slot 'l and the ejection port 8 provide clearance for the locking lugs 9 when the bolt moves forward and backward, while the annular groove 6 forms a recess into which the lugs may turn when the bolt rotates, as hereinafter described, in order to lock the breech.

The lower section of the trunnion block is also bored out, and the axis of the cylindrical cavity so formed coincides with that of the cylinder tube 3 and runs parallel to the axis of the barrel and the bolt. At the rearward end of the trunnion block, the metal 'between this cylindrical cavity, and the bolt way is cut away to provide clearance for the cartridge as it is transferred from the belt to the chamber, and also to provide clearance for the feeder 42, as will be hereinafter explained.

The passageway for the cartridge belt is cut transversely through the trunnion block and is so located that it opens into the cylindrical cavity just mentioned. This belt passageway is formed to provide the curved surface Il, Fig. 16, which insures proper engagement between the loaded belt and the feedwheel 2|. At its entrance end, the passageway is just slightly wider than the lengths of a cartridge, while at its exit end 14, it is wide enough only to permit ejection of the empty belt. There is no necessity for the exit end of the passageway to curve around the periphery of the feedwheel, as does the entrance end.

An important feature in the design of this gun is the longitudinal location of the belt passageway with respect to the barrel and to the mechanism in general. As shown in the drawings (Fig. l) the rearward edge |2 of the metallic belt link I3 is in the same vertical plane as the vertical surface |4 of the trunnion block 2, and the belt passageway is deliberately located to produce this condition, With the belt in this longitudinal position the mechanism of the gun becomes as compact as possible. If the belt were located further ahead, the receiver would require additional length at its forward end and the length of the slide stroke would have to be increased, which would require additional length to the receiver at its rearward end. This matter will be further clarified in a later paragraph.

Running through the center of the cylinder tube 3 and adapted to a reciprocating movement, is the slide l5. This member consists of a heavy round tube rigidly xed at its rearward end of the slide bracket I6, so that these two members function as a single piece. The slide is guided at its forward end by the collar 21 (Fig. 20) which is fixed inside the cylinder tube, and at its rearward by the bracket IB, which has the same cross sectional shape as the inside of the receiver casing, and has a free sliding :dt therein. n

The stripper |1 is bored out to permit the passage of the slide tube I5 and has an outside diameter such that it will have a reasonably snug fit in the rearward end of the cylindrical cavity in the lower part of the trunnion block as shown in Figs. 17 and 18. The stripper is held against longitudinal displacement by means of the member I8 (Fig. 18), which will be further explained hereinafter. The upper portion of the stripper is cut away to provide clearance for the cartridges in the belt, and the upward projecting member 20 (Figs. 3 and 4) on the stripper serves to hold the belt against displacement when the cartridges are extracted therefrom.` The stripper also functions as a thrust bearing forthe feed- Wheel 2|.

The feedwheel is bored out so that the slide tube l5 may pass through it, and so that the feedwheel may rotate upon the slide. A plurality of concave grooves lying axially and adjacent one another around the periphery of the feedwheel are adapted to engage with the belt of cartridges in such a manner that when the feedwheel rotates, the belt will be advanced into the gun.

The cam sleeve 22 is mounted on the slide immediately forward of the feedwheel, the slide having a free sliding fit therein. On its rearward end, the cam sleeve is provided with ratchet teeth 23, which engage with similar ratchet teeth on the forward end of the feedwheel 2|. The cam slot 24, cut into the cam sleeve, is adapted to receive the pin 25 which is fixed in the slide. When the slide reciprocates, therefore, the pin 25 will ride back and forth in the slot 24, and when in engagement with the helical portion of the slot 24, will cause the sleeve to rotate. During the rearward stroke of the slide, the sleeve will transmit its rotation to the feedwheel through the ratchet teeth 23, thus advancing the belt.

During the forward stroke o-f the slide, the cam sleeve will be rotated in the opposite direction. The feedwheel will remain stationary, however, being held against counter-rotation by any suitable means (not shown). rThe ratchet teeth 23 naturally permit the counter-rotation of the sleeve 22 while the feedwheel remains stationary. When the sleeve has been counter-rotated the full amount A-by the forward-moving pin 25, the spring 26 (Fig. 20) snaps the sleeve back into engagement with the feedwheel, the ratchet teeth thus being reset and ready for the next cycle of operation. This mechanism, therefore, is adapted to feed the belt into the gun with an intermittent movement. The spring 26 serves at all times to press the sleeve against the feedwheel and thereby also serves to press the feedwheel against the stripper It is of course necessary that the ratchet teeth 23 and the slot 24 be so proportioned to give the feedwheel the precise amount of rotation required to advance the belt, during each cycle, a distance equal to the space Abetween the centers of the cartridges in the belt,

Inside the tubularslide is the spring 28 con-` fined at its forward end by the pin 25 and at its rearward end Iby pin 29. The rod 30 serves to hold the spring in line with the bore of the slide.

The forward end of the slide is formed as a piston and is adapted to receive the expanding gases which are tapped from the barrel through the gas port 69. The design of gas operated machine guns is well understood in this respect, and inasmuch as any practical design of gas cylinder would be satisfactory for use in this weapon, there is no need to explain this part of the mechanism in detail. As is usual in gasoperated guns, the slide I5 of this weapon is driven to the rear by expanding gases tapped from the barrel. This rearward movement loads the spring 28 which returns the .slide to its forward position after the limit of rearward movement is reached.

The slide bracket |8 is -bored through on a line coinciding with the axis of the barrel, to receive the bolt l0. A second, smaller hole is drilled through the bracket at right angles to the first to receive the pin 3|. pass through the cam slot 32 in the bolt, and

lthe movement of thev pin 3| along these slots at the beginning of the slides rearward stroke is the means whereby the bolt is rotated and thus unlocked. AIt is necessary to provide means for holding the bolt stationary with respect to the slide Ibracket during the entire cycle except. of

The pin 3| is adapted to.,

course when the slide is unlocking or locking the bolt. These means are secured by adapting the pin 3| to a slight transverse movement in the slide bracket and providing it with the maleconical surface 33, Figs. 15 and 22, which may engage as shown in Figs. 4 and 15 with a correspending female conical depression located at the rear end of the cam slot 32. A bevel 34 is formed on the receiver casing at the rear end of the ejection port as shown in Figs. 2 and 23, so that it m-ay engage a projection 35 on the pin. As the slide moves to the rear, the -bevel 34 will act on the projection 35 to press the pin inwardly to the locked position of Fig. 15 and so engage the conical part of the pin with the corresponding recess on the bolt. This occurs immediately after the slide unlocks the bolt from the trunnion and serves to lock the bolt to the slide bracket. The projection 35 rides against the inside of the receiver casing, as shown' in Fig. 15, during the remainder of the rear stroke and for a corresponding period on the forward stroke, thus holding the pin and its conical surface 33 in engagement with the corresponding depression on the bolt.

At the end of the bolts forward stroke, the pin 3| and its projection 35 being opposite the ejection port and out of engagement with the bevel 34, there is nothing to prevent the conical sur-Y faces from camming the pin outward in order to allow the continued forward movement of the slide, which is of course necessary to turn the bolt and lock it to the trunnion block.

The ring pin 35 is retained in thebolt by the pin 31 and is provided with the rebound spring 38 (Fig, 1). The ring pin is driven forward to re a cartridge by the pin 3|, which, as previously explained, is mounted in the slide bracket. The pin 3| is so located with reference to the rear end of the firing pin 3B, that the gun will re just as the slide reaches the limit of its forward movement. Since the bolt is inevitably locked when the slide is in this position, it is mechanically impossible for the gun to fire if the bolt is not completely locked.

The extractor 39 (Figs. 4, 5 and 6) is pivoted at l and is provided with a strong coil spring under its rearward end. This spring does not show in the drawings, but the entire extractor mechanism is conventional and any person faf miliar with the art will readily understand it. The ejector, shown at 4| (Fig. 8) is a small detent which can project about one-tenth of an inch from the face of the bolt and is actuated by a strong spring not shown. Its action is similar to the ejector on the U. S. semi-automatic rifle MI (Garand) and also to that on certain other familiar automatic and semi-automatic small arms.

To accomplish the extraction ofthe cartridges from the belt and their transfer to the barrel 5, a

feeder 42 is provided. The feeder is shown as carried by a round shank 43 mounted with a sliding t in a hole in the slide bracket. The axis of this hole, and therefore the axis of the feeder shank 42, is parallel to the two other main axes of the gun, namely, the axis of the slide and that of the barrel. The forward end of the feeder is adapted to receive and hold a cartridge in a manner to be fully explained hereinafter. The round shank 42 of the feeder is bored out for lightness and is provided with the cam slots 43. rThe pin 44 mounted in the slide bracket passes through and engages the cam slots in the feeder shank. At the rearward end of the feeder shank is provided the pin 45, which is held in the feeder shank by the spring pressed detent 46 and which is adapted to engage the cam slots 41 of the backplate cam 48.

The forward end of the feeder consists of a cartridge-feeder `head which slips endwise over the leading cartridge in the cartridge belt, grasps the cartridge firmly, extracts the cartridge from the belt, and while firmly holding the cartridge moves to a delivery position adjacent to the path of the bolt, and finally guides the cartridge while the bolt pushes the cartridge into the chamber of the gun. The cartridge-feeder head is open at its forward end and comprises two longitudinally extending guide ribs 5| (Figs. 2 and 3) spaced apart less than the diameter of the cartridge, and carried by two flanges 5|) which receive the cartridge between them. A follower member 52 in the form of a spring-pressed arm pivoted at 53 is adapted yieldingly to press the cartridge toward the guide ribs 5|, and when the cartridge is so positioned, a portion of the cartridge protrudes laterally from the cartridgefeeder head in the opening `between the guide ribs 5|, 5| as shown for example in Figs. 2, 5 and 11.

In the forward or receiving position of the cartridge-feeder head, it lies in a recess in the trunnion block 2 above the main body of the stripper member I7, engaging the leading cartridge in the belt, as shown in Figs. 1, 2, 3, 17 and 18, with the flanges 5|] horizontal and with the ribs 5| and the open side of the cartridge-feeder head facing the next succeeding cartridge in the belt. In this forward or receiving position the cartridge-feeder head cannot rotate, the shape of the adjacent surfaces of the trunnion block 2 and stripper member Il precluding such rotation, as shown in Fig. 17.

As the slide moves to the rear from its extreme forward' position, it will carry the feeder rearwardly with it. The pin 44, engaging the annular portion of the cam slot |53 (Fig. 1) acts to lock the feeder against any longitudinal displace ment in the slide bracket. When the feeder has been carried back far enough for its forward end to clear the trunnion block, lthe pin '115 in shank l2 engages with the cam slots El' in the back plate cam 48 causing the feeder to be rotated in the direction indicated by the arrow X, Fig. 5, to the position of Figs. 4, 5 and 6. The amount of feeder rotation produced by the cam slot 4l and the pitch of the cam slot 4l are such that the pin 44 will be clear of the annular portion of the feeder shank cam slot 1|3 at the same time that the feeder reaches the limit of its rearward stroke. The stroke of the feeder from its extreme forward position to its extreme rearward position cating the belt should now be apparent. If Vthey belt were located further forward, the feeder stroke would have to be lengthened in order to bring the cartridge back far enough for its bullet tip to clear the vertical surface lll, so that the cartridge may be lifted. Lengthening the feeder stroke would in turn require lengthening of the slide and bolt strokes for reasons hereinafter appearing, thus requiring thel over-all length of v the mechanism to be increased` As the slide continues to move, after the feeder has been stopped, the pin 44 rides into the helical portion of the feeder shank cam slot 43 and continues to rotate the feeder. The helical portion of cam slot 43 has the same pitch as the cam slot 41 and therefore the feeder is rotated at a continuous, uniform rate. The total rotation of the feederin the structure shown is 90, the rst 30 of which is produced by the back plate cam 48, while the feeder is still moving and the subsequent 60 of which is produced by the passage of the pin 44 through the cam slots 43 after the feeder has reached the limit of its rearward travel. The function of the back plate cam ,43 is essentially to clear the annular portion of slot 43 in the feeder shankof the pin 44. The helical portion of the slot 43 in the feeder does the bulk of the work of rotating the feeder. It is desirable to arrange the cams in this manner because it permits them to have a more gradual pitch for a given feeder stroke. If, for instance, the back plate cam were to rotate the feeder 60 rather than 30, and the rearward stroke of the feeder were not to be increased, the cam slot 41 would have to have twice as steep a pitch as it does in the arrangement shown in the drawings. Insofar as the mechanism operates at high speed, it is obviously desirable to design the various cam slots to have as long a pitch as possible.

Fig. 4 illustrates the mechanism just as the feeder is brought to a stop by the pin 45 as it reaches the end of the helical portion of slot 41 in the back plate cam. As the slide continues tothe rear, turning the feeder further, the pin 45 is turned into the annular portion or continuation of the slot 41, thus locking the feeder against any longitudinal movement whatever. After the feeder has been completely rotated to the position of Figs. 7, 8 and 9, the pin 44 passes into the straight section of the slot 43, and by this means the feeder is also held against any rotation. Once the pin 44 is riding in the straight or axial portion of slot 43 no further movement of the feeder takes place during the remainder of the slides rearward stroke. The rearward limit of the slides stroke is defined by the buffer 49, and when this limit is reached, and the slide is moved forward by the spring 28, the feeder` goes through the reverse of the movements just explained.

In both the rearward and forward strokes of the action slide, the rotary and reciprocating movements of the feeder bar the same relation to the reciprocating movement of the action slide. Thus, the rotation of the feeder to delivery position ends when the slide and bolt are in the I' position of Figs. 7, 8 and 9 going rearwardly, and the rotation of the feeder to receiving position begins when the slide and bolt are in this Isame position of Figs. '7, 8 and 9 going forwardly. Likewise, the rearward reciprocation of the feeder to delivery position ends when the slide and bolt art in the position of Figs. 4, 5 and 6 going rearwardly, and the forward reciprocation of the feeder to receiving position begins when the slide and bolt are in this same position of Figs. 4, 5 and 6 going forwardly. There is a similar identity of positions of these parts for each lposition of the of the cartridge which is to be extracted 'from they belt during the next cycle, and the two flanges 50 will again lie horizontally, directly above and below the cartridge, as shown in Figs. 1, 2 and 3.

The feeder head should be as long as possible, or, in other words its two flanges should extend as far forward along the cartridge as possi-ble. A narroW belt, such as that used in the Browning machine gun is to be preferred for use in this gun. The Browning belt exposes a very considerable length of the base end of the cartridge, permitting in this mechanism the use of a feeder head having suicient length to properly perform its function of holding and guiding the cartridge.

Mounted in the feeder head and adapted to a slight sliding movement therein, is the belt extractor 54. This member is cylindrical in shape and so formed at its inner end that it Iwill ride over the base of the cartridge at the end of the feedersv forward stroke and engage the rim or cannelure of the cartridge. It is held in engagement with the cartridge him or cannelure by the spring 55,.mounted in slot 53 in the slide bracket. The pin 5.1 (Fig. 8) serves to retain the belt extractor in the feeder and limit its movement as well as to hold it against rotation. This retain ing pin acts on the -belt extractor in much the same manner as the pin I9 acts on the stripper retaining piece I8, (Fig. 18).

By means of the engagement of the belt extractor in the cannelure of the cartridge, the cartridge will be Withdrawn from the belt when the feeder moves to the rear. The spring pressed arm 52 also serves to steady the cartridge by holding it firmly against ribs 5|. As the feeder nears the limit of its rearward movement it will begin to rotate, as previously described. The center of the cartridge is so positioned with respect to the axis of the round feeder shank 42, that the rotation of the feeder will elevate the cartridge. When the feeder actually reaches the limit of its rearward movement (Figs. 4, 5 and 6 show the mechanism at this stage), the slide, continuing to move rearwardly will carry the pin 44 through the helical portion of slot 43 in the feeder shank, causing the feeder to rotate further until a total of of feeder rotation has been achieved, and the delivery position of the cartridge-feeder head shown in Figs. 7 to 12 is attained. The cartridge-feeder head reaches this delivery position While the forward face of the rearwardly-moving bolt is still forward at the cartridge-feeder head, as shown in Fig. 7. The cartridge comes into contact with the bottom of the bolt I0 before the rotation of the feeder is complete, and since the approximity of the bolt prevents further elevation of the cartridge, the upward rotation of the feeder subsequent to that point results, in effect, in pressing the cartridge downward with respect to the feeder head. This relative movement between the feeder head and cartridge acts to press the arm 52 downward around its pivot 53 against the spring 58. The

same movement also slides the belt extractor 54 downward and outward; it will be seen in Fig. 8 that the rotation of the feeder head removes the belt extractor from the influence of the belt `extractor spring 55.

With the feeder head completely elevated, then, the flanges 50 will be in a vertical position and the cartridge will be riding against the bottom of the rearward moving bolt l0 against which it is held by the arm 52 as shown in Figs. 7, 8 and 9. As soon as the forward end of the rearwardly moving bolt clears the base of the cartridge, the arm 52 actuated by spring 58 will lift the cartridge about 1/8", where it will again be held by the guide ribs 5| and where it lies in the path of the bolt asA shown in Figs. 10, 11 and 12. The belt extractor, being out of engagement with its spring, will remain in its downward position, and is thus disengaged from the cartridge. When the slide and bolt move forward after completing their rearward stroke, the bolt will push the cartridge forward toward the chamber, in much the same manner that the bolt feeds a cartridge to the chamber in magazine-fed weapons. The lramp 59 (Figs. 10 and 1S) lifts and guides the bullet tip, and the ribs I, against which the cartridge is held by the arm 52, guide the base end of the cartridge. When the cartridge has been moved forward suiiiciently to clear the feeder head and ribs 5|, the supplementary ramp 6i), 60, Fig. 18, in the trunnion block serves to prevent the rear end of the cartridge from dropping down out of engagement with the bolt. Continued movement of the slide will then rotate the feeder downward again bringing the belt extractor 5 into engagement with its spring 55. A bevel 5I is provided on the outside end of the belt extractor (Figs. 8 and 11) in order to enable the spring 55 to iirst cam the belt extractor inwardand then slip over the end of the belt extractor.

From the foregoing, it will be seen that the feeder performs the following functions and movements in the course of a cycle: moves back, pulling the leading cartridge from the belt, rotates, thus lifting the cartridge, and then stands still until the slide and bolt complete their rearward stroke. On the slides forward stroke, it goes through the reverse movement. Thus it remains stationary until the guiding eifect of its ribs 5| are no longer needed to chamber the cartridge. then turns down and goes forward to seize the neXt cartridge, the belt having been advanced meanwhile, as previously explained.

The advancement of the belt during the rear stroke does not begin until the feeder has traveled to the limit of its rearward movement. The straight or axial portion of the cam sleeve slot 2li makes provision for this timing, which is necessary to prevent interference between the feeder together with the cartridge it is holding, and the belt, as the latter is advanced into the gun.

For the manual operation of the mechanism the cooking handle 62 is provided. This member extends forwardly along the inside of the receiver casing, clearance being provided for it by the cuts S3 in the back plate M (Fig. l5), and the slidebracket IB. Its forward end fits into a recess, not shown, in the rear end of the trunnion block, and is provided with a lug or hook which adapts it to engage with the slide bracket in such a manner that when the cooking handle is drawn rearwardly by the operator, the slide will also be drawn back. The cocking handle does not move when the gun is firing, and a small spring catch may be provided to hold this member in its forward position when not in use.

The firing of the gun may be controlled by any conventional trigger and sear mechanism. This mechanism should so act that when the trigger is released some form of sear will hold the slide in its rearward position. This is an almost mandatory requirement in air-cooled machine guns because such high barrel temperatures are produced that if a live round is permitted to remain in the chamber for any length of time there is a liability of its being fired by becoming too hot. In this gun it is also necessary for the scarto hold the slide back because the forward stroke of the slide is utilized to actuate the firing pin. In Fig. 19 I show a suitable form of pistol grip 'l5 and suggest a desirable form of trigger 16.

This grip would presumably be formed integral with or be rigidly attached to the back plate 64.

The back plate has the same cross sectional shape as the trunnion block and slide bracket, and is a push t in the rear end of the receiver casing. It is held in place by the two transverse screws 65.

It is desirable in air cooled machine guns to provide for the quick dismounting of the barrel in order that a hot barrel may be readily replaced by a cool one with a minimum loss of time. To make this operation of utmost convenience to the gunner, I provide the sleeve 66 which is bored out to receive the barrel andis pivoted at 61 on the forward end of the rigid gas cylinder and cylinder tube assembly 3 and 68. The barrel has a sliding iit in the sleeve 6'6, and, as previously explained, is locked at its breech end to the trunnion block by any suitable means, but preferably by heavy screw threads of either the continuous or interrupted type. A supplementary, spring-actuated latch may b-e employed to lock the barrel against any rotation and thus prevent the threads from becoming disengaged. The gas port 69 in the barrel must be so located that when the barrel is assembled into the gun, the port 69 will register with the passage 10 in the gas cylinder.

To remove the barrel, the gunner will unlock it from the trunnion block and slide it forward in the sleeve 66 until the breech end of the barrel is entirely clear of the trunnion. The breech end of the barrel is then lifted enough `to bring it out of line with the trunnion, whereupon it may be withdrawn rearwardly from the sleeve 66. "The pivot 61 of course adapts the sleeve 66 for the rotation necessary to facilitate this lifting of the breech end of the barrel. With this arrangement the barrel may be removed rearwardly without disassembling the remainder of the gun, so that the operator will be enabled to change barrels quickly and without the necessity of leaving his position behind the gun.

To disassemble the mechanism, the. gun is cleared of the belt and the slide is brought to its rearward position (Fig. 10). The rod 30 is pushed inward about by means of the button on its rearward end, and given a quarter turn. As the rod 30 is pressed inward the ends of the pin 29 will pass through clearance slots 80 (Figs. 1 and 14), not shown, in the slide bracket l5, and when the rod isturned -the ends of the pin will engage in the recesses Il (Fig. l) thus locking the driving spring into the slide. The two bolts are then removed, permitting removal of the back plate 64. The slide is then pulled -back a half inch or so further than the limit of its rearward movement with the back plate in place, thus bringing the hole 12, indicated by dotted lines in Fig. 18, into registration with the stripper lock I8. The stripper lock is a small cylindrical member retained in a radial hole in the stripper H by means of the pin I 9, Fig. 18. With gun assembled, the stripper lock extends into a hole in the trunnion and is held in this position by the v slide l5, thus locking the stripper against any abling this member to be'pushed inward by means of a bullet tip or other convenient instrument applied to its outer end through the hole 13 in the casing. Having thus been moved inward, the

stripper lock will be disengaged from the trunnion and the stripper `-will be free to move rear wardly. The slide is then withdrawn' rearwardly from the gun, carrying vwith it the bolt, the feeder, the stripper, the feed `wheel and the cam sleeve, to which is attached the cam sleeve spring 26. It is obvious Ithat the stripper lockV described herein is merely a suggested arrangement 'and that it can be designed in many different ways.

The rear sight 11 is mounted on the rear of the receiver casing and is of conventional design. The front sight 18 is formed integral with the barrel sleeve 66.

A circular recess 'I9 on either side of the receiver casing provides means whereby the weapon may be moun-ted on a tripod.

The foregoing, beings. complete description of the gun, I claim: f

1. In a machine gun of the type adapted to receive a cartridge belt and including a cartridge belt-feeding mechanism and a reciprocable breech bolt, the combination of r an action-slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the action-slide and also rotatable about an axis extending longitudinally of the gun, the reciprocation and rotation of the cartridgefeeder head carrying it between a cartridgereceiving forward position adjacent to a cartridgebelt received in operative position within the gun and a cartridge-delivery rearward positionadjacen-t to the path of the breech bolt; said cartridge- 9 feeder head being shaped -to receive and discharge a cartridge through its forward end; a belt extractor carried by the cartridge-feeder head for extracting a cartridge from such belt; and cam mechanism for rotating the cartridge-feeder head about said axis toward said delivery position after the cartridge therein has been extracted from such belt and toward said receiving position after the cartridge has been pushed out of the cartridge-feeder head by the forwardly moving bolt.

2. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-'feeding mechanism; an action-slide; a breech bolt reciprocable forwardly and rearwardly by the action-slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the action-slide and also rotatable about an axis extending longitudinally of the gun, the reciprocation and rotation of the cartridgefeeder head carrying it between a cartridge-receiving forward position adjacent to such cartridge belt and a cartridge-delivery rearward position adjacent to the path of Ithe breech bolt; a belt extractor carried by the cartridge-feeder head for extracting a cartridge from such belt; and cam mechanism for rotating the cartridge-feeder head about said axis, said cam mechanism being timed with relation to the reciprocation of the bolt to complete the rotation of the cartridgefeeder head to said delivery position before the forward face of the rearwardly moving bolt reaches said delivery position of the cartridgefeeder head and to initiate the rotation of the cartridge-feeder head to said receiving position after the forward face of the bolt has moved forwardly past said cartridge-feeder head.

3. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; an action-slide; a breech bolt reciprocable forwardly and rearwardly by the slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the action-slide and also rotatable about an axis extending longitudinally of the gun, the reciprocation and rotationof the car# tridge-feeder head carrying it between a cartridge-receiving forward position adjacent to such cartridge belt and a cartridge-delivery rearward position adjacent to the path of the breech bolt; the stroke of reciprocation of the cartridgefeeder head being materially shorter than the stroke of reciprocation of the breech bolt; a belt extractor carried by the cartridge-feeder head for extracting a cartridge from such belt; and cam mechanism for rotating the cartridge-feeder head about said axis, said cam mechanism being timed with relation to the reciprocation of the bolt to complete the rotation of the cartridge-feeder head to said delivery position before the forward face of the rearwardly moving boltyreaches said delivery position of the cartridge-feeder head and to initiate the rotation of the cartridge-feeder head to said receiving position after the forward face of Vthe bolt has moved forwardly past said cartridge-feeder head.

4. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; an action slide; a breech bolt reciprocable forwardly and rearwardly by the slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the action-slide and also rotatable about an axis extending longitudinally of the gun, the reciprocation and rotation of the cartridgefeeder head carrying it between a cartridge-receiving forward position adjacent to such cartridge belt and a cartridge-delivery rearward position ladjacent to the path of the breech bolt; the stroke of reciprocation of the cartridgefeeder head being materially shorter than the stroke of reciprocation of the breech bolt; a belt extractor carried by the cartridge-feeder head for extracting a cartridge from such belt; and cam T mechanism for rotating the cartridge-feeder head about said axis, said cam mechanism being timed with relation to the reciprocation of the -bolt to complete the rotation of the cartridge-feeder head to said delivery position before the forward face of the rearwardly moving bolt reaches the delivery position of said cartridge-feeder head and to initiate the rotation of the cartridgefeeder head toA said receiving position after the forward face of the bolt hasrmoved forwardly past said cartridge-feeder head; the cartridgefeeder vhead being shaped to permit reception and discharge of the cartridge only through its forward end, a lateral Vface of the cartridge-feeder head being open to expose a portion of the cartridge therein to forwardpushing action of the breech bolt.

5. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; an action-slide; a breech bolt reciprocable forwardly and rearwardly by the action-slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the slide and also rotatable about an axis extending longitudinally of the gun, the reciprocation and rotation of the cartridgefeeder head carrying it between `a cartridge-receiving forward position adjacent to such cartridge belt and a cartridge-delivery rearward position adjacent to the path of the breech bolt; the stroke of reciprocation of the cartridge-feeder head being materially shorter than the stroke of reciprocation of the breech bolt; a belt extractor carried by the cartridge-feeder head for extracting a cartridge from such belt; and cam mechanism for rotating the cartridge-feeder head about said axis, said cam mechanism being timed with relation to the reciprocation of the bolt to complete the rotation of the cartridge-feeder head to said delivery position before the forward face of the rearwardly moving bolt reaches said delivery position of said cartridge-feeder head and to initiate the rotation of the cartridge-feeder head to said receiving position after the forward face of the bolt has moved forwardly past said cartridge-feeder head; the cartridge-feeder A head being shaped to permit reception and discharge of the cartridge only through its forward end, a lateral face of the cartridge-feeder head being open to expose a portion' of the cartridge to forward pushing action of the breech bolt, and

the cartridge-feeder head including a follower member yieldingly pressing the cartridge toward said lateral face, the follower permitting the cartridge to be pressed inwardly from said lateral face of the feeder head by engagement with the bolt as the feeder head rotates toward said delivery position.

6. In a machine gun, the combination of z an action-slide mounted to reciprocate longitudinally of the gun; a cartridge-feeder head mounted to reciprocate with said slide during at least a part of the reciprocation thereof and also to rotate about an axis extending longitudinally of the gun; and cam mechanism for rotating the feeder head about said axis during the reciprocation of said slide, said cam mechanism operating in both directions of travel of the action slide to cause the rotary movement of the cartridge-feeder head to bear the same relation to the longitudinal movement of the action-slide in both the forward and rearward movements of the actionslide.

'7. In a machine gun, the combination of: an action-slide mounted to reciprocate longitudinally of the gun; a cartridge-feeder head mounted to reciprocate with said slide during a part of the reciprocation thereof and also to rotate about an axis extending longitudinally of the gun; a'lock adapted to cause the cartridge-feeder head to partake of a part of the reciprocation of the actionslide; and cam mechanism for rotating the feeder head about said axis during the reciprocation of said slide, said cam mechanism operating in both directions of travel of the action-slide to cause the rotary movement of the cartridge-feeder head to bear the same relation to the longitudinal movement of the action-slide in both the forward and rearward movements of the actionslide; and means for unlocking said lock at a place in the rearward movement of the action-slide and for locking said lock at the same place in the forward movement of the action-slide.

8. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; a breech bolt reciprocable forwardly and rearwardly; a cartridge-feeder head arranged to receive a cartridge from such belt and to discharge the cartridge through the forward end of the head; a lateral face of the cartridge-feeder head being open to expose a portio-n of the cartridge to forward pushing action of the breech bolt; driving means operating in timed relation to the reciprocation of the breech bolt for moving said cartridge-feeder head from a forward receiving position adjacent to such cartridge belt to a rearward delivery position adjacent to the path of the breech bolt before the forward face of the rearwardly moving bolt reaches said delivery position of the cartridge-feeder head; and a follower member in the cartridge-feeder head adapted yieldingly to press the vcartridge toward said lateral face of the cartridge-feeder head.

9. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; a breech bolt reciprocable forwardly and rearwardly; a cartridge-feeder head arranged to extract a cartridge from such belt and to discharge the cartridge through the forward end of the head, said feeder head including a belt extractor carried by said feeder head for extracting a cartridge from such belt; a lateral face of the cartridge-feeder head being open to expose a portion of the cartridge to forward pushing action ofthe breech bolt; driven means operating in timed relation to the reciprocation of the breech bolt for moving said cartridge-feeder head from a forward receiving position adjacent to such cartridge belt to a rearward delivery position adjacent to the path of the breech bolt before the forward face of the rearwardly moving bolt reaches said delivery position of the cartridgefeeder head; a follower member in the cartridgefeeder head adapted yieldingly to press the cartridge toward said lateral face of `the cartridgefeeder head and the path of the bolt; and means for urging the belt extractor into operative engagement with a cartridge in said receiving position and releasing the belt extractor therefrom in said delivery position- 10. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; an action slide; a breech bolt reciprocable forwardly and rearwardly by the slide; a cartridge-feeder head reciprocable forwardly and rearwardly by the slide, said cartridge feeder head including a belt extractor for extracting a cartridge from such belt; means for terminating the rearward reciprocating movement of the cartridge-feeder head while the slide moves rearwardly and the front face of the breech bolt lies forwardly of the feeder head, allowing the slide and breech bolt to continue to the rear carrying the breech bolt past the cartridge in the feeder head; and means for yieldingly pressing the cartridge in said cartridge-feeder head into the path of forward movement of the bolt; the cartridgefeeder head being shaped to guide the cartridge as the cartridge is pushed forward by the bolt.

1l. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: cartridge belt-feeding mechanism; an action-slide; a rotatable and reciprocable breech bolt; a cartridge-feeder head reciprocable forwardly and rearwardly with the slide during rotation of the bolt and part of the reciprocation thereof, the cartridge feeder head including a belt extractor for extracting a cartridge from such belt and the rearward reciprocation of the cartridge-feeder head being suflicient in length to cause said extractor to extract a cartridge from such belt; means for terminating the rearward reciprocating 4movement of the cartridge-feeder head while the slide moves rearwardly and the front face of the rearwardly moving breech bolt lies forwardly of the cartridgefeeder head; and means for yieldingly pressing the cartridge in said cartridge-feeder head into the path of forward movement of the bolt when the bolt has passed to the rear of the cartridge in the cartridge-feeder head.

12. In a machine gun of the type including a reciprocable breech bolt and a cartridge beltfeeding mechanism, the gun being adapted to receive a cartridge belt in operative position within the gun, the combination of: an action-slide; a cartridge-feeder head reciprocable forwardly and readwardly; an extractor carried by the cartridge-feeder head for extracting a cartridge from such cartridge belt as the cartridge-feeder moves rearwardly; means for rotating the cartridgefeeder head about a longitudinally extending axis to carry it toward and from a delivery position where it delivers the cartridge to the breech bolt; a locking connection between the cartridge-feeder head and the action-slide adapted to cause the cartridge-feeder head to partake of a part of the reciprocation of the action-slide; said locking connection being actuable to unlock by rotation of the cartridge-feeder head toward delivery position and being actuable to lock by rotation of the cartridge-feeder head away from delivery position.

13. In a machine gun, the combination of: an action-slide mounted to reciprocate longitudinally of the gun; a cartridge-feeder head'adapted to discharge a cartridge through its forward end; a lateral face of the cartridge-feeder head being open to expose a, portion of the cartridge; a shank for the feeder head rotatable about a longitudinal axis in the action-slide; a separable cam and cam follower connection between the shank and a fixed part of the gun adapted to rotate the shank as the action-slide moves; a lock between the `shank and action-slide to lock the shank and and action-slide so that they reciprocate together during a part of the reciprocation of the action slide, said lock being adapted to be unlocked by said rotation of the shank during the rearward movement of the slide so that during rearward movement of the slide the cartridge-feeder head is first moved rearwardly while locked to the slide and is then rotated by said cam and cam follower connection and thereby unlocked from the slide.

14. In a machine gun, thecombination of: an action-slide mounted to reciprocate longitudinally of the gun; a cartridge-feeder head movable from a. cartridge-receiving position to a cartridge-delivery position; a shank for the feeder head rotatable about a longitudinal axis in the action slide and reciprocable therein; a lock for preventing reciprocation of the shank relative to the slide, said lock being actuable to unlock by rotation of the shank; a stationary cam adapted to act on the reciprocating shank to rotate the shank and thereby unlock said lock; a stop to detain the'shank against reciprocation in the gun when said lock is unlocked; and a cam between the action-slide and the shank adapted to rotate the shank while the shank is detained against reciprocation by said stop, said last-named cam having a dwell permitting movement of the slide in its rear positions while detaining the shank stationary with the cartridge-feeder head in its delivery position.

15. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of: a cartridge-feeder head open at the forward end and comprising longitudinally extending cartridge-guiding ribs, a follower element adapted yieldingly to press a cartridge against said ribs, and an extractor positioned in the rear of the cartridge-feeder head and arranged to extract a cartridge from such belt; and means for moving said cartridge-feeder head from a cartridge-delivery position to a cartridge-receiving y position where said ribs and assaggiV follower embrace a cartridge lying in normal position in such cartridge belt.

i6. In a machine gun adapted to receive a cartridge belt in operative position within the gun, the combination of a reciprocable action-slide; a cartridge-feeder head open at the forward end and comprising longitudinally extending cartridge-guiding ribs, a follower element adapted to be deilected away from said ribs by a cartridge and adapted yieldingly to urge said cartridge against said ribs, and an extractor positioned in the rear of said cartridge-feeder head and arranged to extract a cartridge from such belt; and means operated by said action slide as it moves forwardly to slip said cartridge-feeder head endwise over the base portion of a cartridge in its normal position in such belt until the extractor in said head engages the extraction groove of the cartridge.

17. In a machine gun adapted to receive a cartridge belt in operative position Within the gun, the combination of a reciprocable action-slide; a cartridge-feeder head open at the. forward end and comprising longitudinally extending cartridge-guiding ribs, a follower element adapted to be deflected away from said ribs by a cartridge and adapted yieldingly to urge said cartridge against said ribs, and an extractor positioned in the rear of said cartridge-feeder head and arranged .to extract a cartridge from such belt; a shank mounting the cartridge-feeder head in the action slide for rotation about a longitudinal axis of the gun; mechanism actuable during forward movement of the action-slide to hold the cartridge-feeder head in a, delivery position, then rotate the shank and cartridge-feeder and advance them longitudinally until said cartridge-feeder head has slipped endwise over the base portion of a, cartridge in its normal position in such belt.

18. In a machine gun of the type adapted to receive a cartridge belt in operative position within the gun and including a cartridge belt-feeding mechanism and a reciprocable breech bolt, the combination of a cartridge-feeder head arranged to carry a, cartridge from such belt to the path of the bolt, said head being shaped to slip over the rear end of a cartridge in such belt, and comprising longitudinally extending guide ribs spaced apart less than the diameter of the cartridge, and a follower member yieldingly tending to press the cartridge against the said ribs; means for reciprocating the cartridge feeder head forwardly and rearwardly of the gun and means for rotating the cartridge-feeder head about an axis extending longitudinally of the gun, to carry the cartridge-feeder head between a forward position in which it engages a cartrigde in such belt with said ribs facing the next succeeding cartridge in such belt and a rearward position in which said ribs lie adjacent to the path of the bolt.

19. In a machine gun of the type adapted to receive a cartridge belt in operative position within the gun and including a cartridge belt-feeding mechanism and a reciprocable breech bolt, the combination of: a cartridge-feeder head arranged to carry a cartridge from such belt to the path of the bolt, said head being adapted to slip over the rear end. of a cartridge in such belt and comprising longitudinally extending guide ribs spaced apart less than the diameter of the cartridge, a follower member yieldingly tending to press the cartridge against the said ribs, and a belt extractor for extracting a cartridge from such belt; means for reciprocating the cartridge-feeder head forwardly and rearwardly of the gun and means for rotating the cartridge-feeder head about an axis extending longitudinally of the gun, to carry the cartridge-feeder head between a forward position in which it engages a cartridge in such belt with said rings facing the next succeeding cartridge in such belt and a rearward position in which said ribs lie adjacent to the path of the bolt.

20. In a machine gun adapted to receive a cartridge belt in operative position in the gun, the combination of: cartridge belt-feeding mechanism adapted to advance a cartridge belt; an action slide; a breech bolt reciprocable forwardly and rearwardly by the slide; a cartridge-feeder head arranged to carry a cartridge from such belt to the path of the bolt, said head being shaped to slip over the rear end of a cartridge in such belt, and comprising longitudinally extending guide ribs spaced apart less than the diameter of the cartridge, a follower member yieldingly tending to press the cartridge against the said rigs, and a belt extractor for extracting a cartridge from such belt; means for reciprocating the cartridge-feeder head forwardly and rearwardly of the gun and means for rotating the cartridge-feeder head about an axis extending longitudinally of the gun and offset with respect to the axis of the lsaid cartridge in such belt to carry the cartridge-feeder head between a position in which it engages the cartridge in such belt and a position in which it holds the cartridge against the side of the rearwardly moving bolt; the rearward movement of the bolt being sucient to carry its front face to the rear of the said cartridge in the said cartridge-feeder head, and the follower member thereupon moving the cartridge in the cartridge-feeder head into the path of the forward movement of the bolt, and the said ribs and follower member serving to guide the cartridge a-s it is pushed forward by the bolt.

21. In a machine gun, the combination of an action slide mounted to reciprocate longitudinally of the gun; a breech bolt adapted to reciprocate with the action slide; a cartridge-feeder mounted to reciprocate with the action slide during the first part of the reciprocation of the action slide; means for terminating the rearward reciprocating movement of the cartridge-feeder while the action slide continues to move rearwardly;

and an interconnection between the action slide and cartridge-feeder for retaining the cartridgefeeder at a predetermined position with respect to the path of the bolt as the bolt is moved rearwardly past the cartridge-feeder.1

22. In a machine gun adapted to receive a cartridge belt in operative position in the gun, the combination of a breech bolt reciprocable forwardly and rearwardly of the gun; a rearwardly movable belt-extractor comprising a member adapted to engage the rim of a cartridge in such belt; means for causing said rim-engaging member to release the cartridge rim of the extracted cartridge; and spring-pressed means for pressing the extracted cartridge against the bolt as the bolt moves rearwardly, so that when the forward face of the bolt passes the rearward face of the extracted cartridge, the cartridge is moved by said spring-pressed means into position to be engaged by the forward face of the Ibolt upon forward movement of the bolt.

23. In a machine gun adapted to receive a belt of cartridges in operative position within the gun, the combination of: a breech bolt reciprocable forwardly and rearwardly of the gun; cartridge belt-feeding mechanism, the belt-feeding mechanism being located to position such belt of cartridges with their rear faces substantially to the rear of the forward position of the forward face of the bolt; a rearwardly movable belt-extractor comprising a member adapted to engage the rim of a cartridge in such belt; means for causing said rim-engaging member to release the cartridge rim of the extracted cartridge; and springpressed means for pressing the extracted cartridge against the bolt as the bolt moves rearwardly, so that when the forward face of the bolt passes the rearward face of the extracted cartridge, the cartridge is moved by said springpressed means into position to be engaged by the forward face of the bolt upon forward movement of the bolt.

WILLIAM B. RUGER.

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