US2751820A - Trigger and sear control mechanism - Google Patents

Description

June 26, 1956 A. J. POPE TRIGGER AND SEAR CONTROL MECHANISM 3 Sheets-Shea t 1 Original Filed June 24. 1950 Zhmentor (\1 men/17R OPE mm m wm m June 26, 1956 A. J. POPE TRIGGER AND SEAR CONTROL MECHANISM 3 Sheets-Sheei 2 Original Filed June 24, 1950 June 26, 1956 A. J. POPE .TRIGGER AND SEAR CONTROL MECHANISM Original Filed June 24, 1950 5 Sheets-Sheet III/I United States I atent O TRIGGER AND SEAR CONTROL MECHANISM Arthur J. Pope, Madison, Conn.

Original application June 24, 1950, Serial No. 170,178. Divided and this application May 3, 1952, Serial No. 285,839

6 Claims. (Cl. 89-140) This invention relates to firearms of the type that utilizes a breech block or bolt that responds to the reaction of the explosive for achieving cyclic actuation of the gun. This application is a division of my application Serial No. 170,178, filed June 24, 1950.

One of the objects of this invention is to provide an improved trigger and sear control mechanism for a gun of the above-mentioned type that will be of compact, strong and not unwieldy, construction, of smooth and efiicient action, and of simple and easy manual selective control. Another object is to provide an efi'icient and reliable receiver and bolt construction, action and assembly in which pneumatic action and spring action combine to give smoothness and ease of gun operation and facilitate coaction with trigger and sear for consistently dependable manual selective control.

Another object is to provide a sear control and trigger mechanism that will give ease and simplicity of action and selectivity for single fire, manual repeat firing, or automatic successive firing, and also dependable and consistent coaction with the breech block or bolt. Another object is to provide a dependable and rugged sear control and trigger mechanism that is of individually simple parts which are not costly to manufacture and are capable of ready assembly to provide positiveness and ease of manual control and action under the varying conditions of practical use.

Another object is to provide a trigger mechanism of the above-mentioned type particularly adapted for coaction with a recoil-reactive bolt movement and that is simple inconstruction and action, inexpensive in construction and assembly, that makes for ease and simplicity of construction, that is reliably selective and consistent in action, that will give smoothness, ease, and precision in handling and operation with minimum interference with precision of firing, and that permits of long-continued use with minimum of need for repair or maintenance on the part of the user. Another object is to provide a trigger and/ or sear construction and control of the above-mentioned type in which the mechanism and construction facilitate simplicity of manufacture, expedite large-scale production and assembly, avoid such precision of relative dimensioning of parts as millitates against inexpensive manufacture, simplicity of maintenance and care, and consistency of performance in practical use.

Another object is to provide a trigger mechanism of the above-mentioned character in which ruggedness and durability of construction are combined with simplicity of protection against usual but hard conditions of practical use and with simpicity and ease of use, care, and maintenance.

Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combination of elements, and arrangement of parts as will be exemplified in the structure to be described hereinafter and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is shown illustratively one of the various possible embodiments of my invention,

Figure 1 is a central longitudinal vertical sectional View of a gun construction embodying a trigger and sear control according to my invention, certain parts being broken away or omitted for greater simplicity of exposition;

Figure 2 is an end elevation partly in section as seen along the line 22 of Figure 1, showing also the rear slight and an illustrative hand grip;

Figure 3 is a transverse vertical section as seen along the line 3-3 of Figure 1, showing the relationship between the receiver, the breech block, and other parts for achieving a compound pneumatic action;

Figure 4 is a horizontal fragmentary sectional View as seen along the line 44 of Figures 1 and 2, showing certain parts of the end closure for the receiver and of the rear sight mechanism;

Figure 5 is a transverse vertical sectional view on an enlarged scale as seen along the line 5-5 of Figure 1, showing certain features of the trigger mechanism in its relation to the breech block;

Figure 6 is a transverse vertical sectional view on an enlarged scale as seen along the line 6-6 of Figure 1, showing certain relationships between the bolt and the ejector and showing also certain parts of the trigger assembly;

Figure 7 is a transverse vertical sectional view as seen along the line 77 of Figure 1, showing part of the retractor mechanism;

Figure 8 is a vertical sectional view of a portion of the illustrative gun structure as seen along the line 88 of Figure 7 and showing parts of the retractor mechanism;

Figure 9 is an isometric View on an enlarged scale of a subassembly of the trigger mechanism;

Figure 10 is an isometric view on a much smaller scale of a preferred form of part for closing off the rear end of the receiver;

Figure 11 is a central longitudinal vertical sectional view on an enlarged scale of the trigger and sear mechanism which is also shown in Figure 1;

Figure 12 is a transverse vertical sectional view as seen along the line 12-12 of Figure 11, showing the mounting of the sear;

Fig. 13 is a vertical sectional view as seen along the line 13 13 of Figure 11, showing on an enlarged scale a manually controlled mechanism for setting the range of trigger movement;

Figure 14 is a vertical sectional view as seen along the line 14-14 of Figure 13; and

Figure 15 is a transverse vertical sectional view as seen along the line 15-15 of Figure 1, showing the gun with a cartridge magazine attached.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring first to Figure 1, the gun construction may comprise a tubular receiver 10 having fitted at its front end and secured to it as by threads 13 a short and suitably heavy member 11 later described which has attached coaxially thereto a gun barrel 12 which may be rifled. Barrel 12 is threaded into the mounting member 11 so that shoulder 15 of the barrel abuts securely against the internal shoulder 14 of member 11. Member 11 fits snugly into receiver 10, being secured thereto, as by welding, as at 16.

Inserted into the rear or left-hand end of the receiver 10 is a breech block or bolt structure 18 comprising a relatively long, hollow, cylindrical block 19 reciprocally movable in the receiver 10; at its right-hand or forward end it has an integral bolt 20 for coaction with the cartridges. Block 19 may have a long internal bore 21 that is open at its left-hand end and of a diameter and length to leave a mass or weight of metal in the block 19 which when added to the weight or mass of the bolt 20 is appropriately related to a propulsion spring 22 to insure a forward motion of the block 18 at sufficient velocity to amply provide the energy needed to inject a cartridge into the rear end of the gun barrel 12 and impact the cartridge to detonate the explosive in the shell to propel the projectile along and out of the gun barrel.

Bolt 20 has at its center a firing pin 23 which projects from the base of an end counterbore or turned recess 24 laterally bounded by a flange 25 having suitably curved or shaped internal faces to guide the rear flanged end F of a cartridge C into substantial coaxial relation to the bolt, 20 during the injecting stroke of the bolt structure 1S.

Bolt 20 has a milled slot 26 in which is seated and mounted in any suitable manner any usual or known form of spring clip 27 appropriately toothed at its outer end as at 27 to engage over the peripheral flange F (see Figure 1) of a cartridge C to withdraw or extract the emptied shell S from the gun barrel on the rearward stroke of the block 18.

The empty shell S is carried rearwardly with the bolt 20 and ejected through a suitable receiver side opening 29, being flipped laterally off the end of the bolt 20 when it strikes an ejector pin 30 mounted on the inside of receiver at an angle to a radius by a stud 32 welded in place; pin 30 is in the path of rearward movement of the empty shell carried by the bolt 20 which has a milled slot 31, that also intersects the flange 25, to accommodate the end of the pin 30 therein during the strokes of movement of the bolt 20. The reaction from the detonation impels the bolt structure 18 rearwardly, or to the left in Figure l, at substantial velocity.

In the illustrative form the outside diameter of the block 19 is materially less than the inside diameter of the receiver 10 and the large clearance is thus made to form an air passage that is annular in cross-section. The bore 21 leaves an end annular face 36 at the rear end of the block 19 which can serve as an annular piston in an annular chamber bounded by the inner cylindrical wall of the receiver 10 and the outside wall of a tubular or bored-out part 37 projective coaxially from a relatively heavy cylindrical block 38 that fits snugly into and closes the rear end of the receiver 10 and that has a heavy flange 39 which abuts against the rear end of the receiver 10. In Figure 10 is shown in perspective at 40 the unit structure made up of parts 37, 38, and 39.

Block 38 of member 40 has a diametric hole 41 aligned with diametrically opposed holes 42 and 43 in the thickened walls of the receiver 10, thickened and reinforced by a metal band 44 shrunk onto the receiver 10 or welded or otherwise secured thereto.

As shown in Figure 2, band 44 has two spaced depending lugs or ears 45 and 46 which provide between them a parallel-sided slot 47 whose width is at least as g eat as the diameter of the holes 42 and 43. and whose. median plane is coincident with the common axis of the holes 42 and 43.

Unitary part 40 is locked in position within the receiver 10 by a heavy pin or stud 50 which passes snugly into the aligned holes 43, 41, and 42 (see Figure l) and which has a heavy shank 51 (Figure 2) that is parallel-sided and snugly received at its upper end between the ears 45 and 46. The shank 51 forms or has secured to it any suitable means for mounting or holding the gun and, illustratively, such means may comprise a hand grip 52 (Figures 1 and 2) which may comprise suitably shaped non-metallic pieces 53, 54 secured to. the shank, as by rivets 55. The ears 45 and 46 and the shank 51 have suitable holes which become aligned when the assembly pin or stud 50 is manually forced home, a position (Figure 1) wherein the fiat horizontal face 56 at the upper end of the shank. 51 engages with the flat under face of the heavy band or ring 44, whence a bolt 57 provided with a thumb nut 58. is passed through 4 the aligned holes in the lugs 45 and 46 and the shank 51, thus holding the assembly pin 50 in looking position.

The tubular part 37 (Figure 1) has an interior diameter that is substantial in relation to the inside diameter of the receiver 10 and is closed off at its rear or left-hand end by block part 38 against which abuts one end of the spring 22 which is of relatively large diameter in relation to the tubular part 37 in which it is received and guided, particularly during those portions of movement of the turns of the spring 22 that correspond to high and maximum spring compression. The other end of the spring 22 abuts against the disc-like face 6t) at the inner end of the bore 21 in the breech block 19. In the position shown in Figure 1 the breech block and bolt structure 18 is shown in retracted position in which it is releasably held by a sear 61 later described in detail and the spring 22 is compressed and has stored in it sufficient energy which when released projects the bolt structure 18 forwardly (to the right in Figure l) to inject a cartridge into the barrel and also to detonate its charge.

In the illustrative gun thus far described the tubular part 37 and the bore 21 of the breech block 19, each with one end closed, may be made together to form a chamber X or cylinder of variable volume according to the position of the breeach block 19 in its strokes of reciprocating movement, the inner end face 60 of the bore 21 operating as a piston to change the volume of this telescoping cylinder. This chamber or cylinder of variable volume may be placed in continuous communication with the annular space or chamber X between the block part 30 and the annular piston 36 formed by the end annular face of the breech block 19, as by an annular passage 62 formed between the outside cylindrical wall of the tubular part 37 and the inside cylindrical wall of the bore 21, as by making sure that the diameter of the latter is sufliciently greater than the diameter of the former to provide a large enough clearance between the two to form the desired annular crosssection of passageway. Figures 1, 3, and 5 show in somewhat exaggerated form indicated relationships of the various diameters concerned to provide substantial airways, both at the clearance space 62 and the clearance space 35, and where it is desired that the two airways 35 and 62, both being annular in cross-section, be of substantially the same area, the radial dimension of the airway 62, of course, becomes greater than the radial dimension of the airway 35.

With such arrangement of parts, described in detail and claimed in my parent application, and which may be employed with my trigger mechanism, I am enabled to achieve a number of unique and highly advantageous actions and coactions of and between moving parts and related control mechanisms. The relatively large airways in the illustrative embodiment are formed of surfaces which are geometrically simple and inexpensive to form or machine, being turned or bored or drawn, etc. The purposeful large differences in diameters, for forming these airways, for manufacturing purposes might be considered as exceedingly large clearances; and while 1 facilitate precision of dimensioning during machining of the individual parts or surfaces, it is to be noted that these large clearances not only facilitate assembly but completely avoid any need for costly precision or fitting of one part to or into another; no concern need be given, for example, to such costly considerations as tolerances necessary for a so-called running fit.

Thereby, also, I am enabled to achieve almost frictionless movement of the relatively heavy bolt structure relative to both the inside wall of the receiver 10 and the outside wall of the tubular part 37 in that the piston-andcylinder actions that take place during both strokes of movement of the breech block structure 18 insure movement of air through the annular airways 21 and 35 at suitable. relative. pressures to virtually float the moving bolt structure on the air streams flowing through the two airways. Moreover, though the bolt structure 18, relatively speaking, is heavy, the two annular airways coact with relatively large areas of surfaces of the block 19 so that small relative air pressures per unit area are usable. Also, the relative air pressures exerted in the annular airways 21 and 35 are in each uniformly distributed relative to the axis of the moving bolt structure and exert thereon a nicely balanced and in effect a centering action, tending always to float and maintain the moving breech block 19 in coaxial relation with the fixed coaxial parts, namely, the receiver and the tubular part 37.

When the bolt structure 18 in Figure 1 is released by the sear 61, the energy stored in the spring 22 moves the bolt structure 18 toward the right, to inject the cartridge C into the barrel 12 and impact it with the necessary energy to detonate it.

The detonated explosive propels the projectile P through and out of the barrel 12, and the reaction that results impels the bolt structure 18 rearwardly, or to the left, at substantial velocity and energy; this retrograde movement of the bolt structure 18 compresses the spring 22 to store energy into it for the next firing cycle and coacting with the resistance to compression of the spring 22 to bring the bolt structure 18 to a substantial gentle halt, are the chambers X and Y and the air passages 35 and 62.

In this manner dependable deceleration, particularly during the latter part or parts of the retrograde stroke, and bringing the bolt structure 18 to a momentary halt, are greatly facilitated. Moreover, I am enabled to bring this about while at the same time utilizing a spring 22 of materially less weight and power than would be necessary were the spring 22 to be relied upon solely. The point of momentary halting of the bolt structure 13 is just to the left of the position shown in Figure 1, so that the front end of the breech block part 19 by-passes the sear 61 which, under controls later mentioned, can move upwardly through the slot 64 to enter the receiver 10 and to assume a position to hold the bolt 18 in retracted position against the action of the spring 22. The spring 22 is thus held compressed, so that when the bolt structure 18 is released by actuating the sear 61, the firing stroke of the bolt commences and the cycle above described is repeated. If the sear 61 has been precluded from catching the bolt structure 18 in retracted position, the above cycle will automatically repeat itself.

Desirably, I prefer to employ a scar construction and coacting trigger mechanism that is also capable of use in a gun constructed to have the above-described air-floating actions on the bolt structure, and a preferred form thereof I have shown in the drawings as including the abovementioned sear 61. Both sear and trigger mechanism I prefer to construct as a sub-unit or sub-assembly which may be easily and quickly assembled and also disassemled from the gun structure.

This sub-assembly preferably comprises a casing, generally indicated at 65 (Figures 1, 5, and 6), which may be made of suitably heavy sheet metal stamped or otherwise formed to provide a bottom wall 66 from which there are upstanding parallel side walls 67 and 68 (Figures 5 and 6) and also an end Wall 69. End wall 69 (Figure 1) is provided with a hole 70 into which is received one arm of an L-shaped heavy lug 71 depending from the underside of the receiver 10, near the rear or left-hand end thereof, being secured to the receiver 10 as by welding.

Opposite the end wall 69 of the casing 65, the latter is open so that after first hooking the end wall 69 onto the lug 71 and then swinging the casing 65 in clockwise direction to bring the upper beveled face of the side casing walls 67 and 68 (see Figures 5 and 6) into engagement with the receiver 10, a heavy, relatively large lug 72 (Figures 1 and 6) depending from the underside of the receiver 10 enters in between the side casing walls 67 and 68 at their front or right-hand end, as is better shown in Figures 1 and 6. The lug 72 thus forms the opposite .end wallclosure for the casing 65, and it has a transverse hole '73. with which holes 74 and 75 in the side walls 67 and 68, respectively, become aligned. The hole 74 may be threaded (Figure 6) to receive the threaded end of a screw 76 that passes through these aligned holes and thus detachably holds the casing 65 assembled to the gun structure.

The above-mentioned sear 61 is of a width to fit neatly between casing side Walls 67 and 68, being pivotally carried on a stud shaft that is bridged between these side walls 67 and 68; conveniently that stud is in the form of a stud bolt 77 (see Figure 5) which passes through a suitable hole 78 in the side wall 67 and has its threaded end threaded into a threaded hole 79 in the opposite side wall 68. The sear 61 is preferably in the form of a lever of the first class (see Figure 1) and has two substantially equal arms 61 and 61 making an obtuse angle, as is better shown in Figure 1. The sear 61 is made of any suitable metal, suitably hardened, as may be desired. Side walls 67 and 68 hold the sear 61 centrally of the casing 65 (Figure 5) and against axial shift, while permitting freedom of pivoting, so that assembly of the casing 65 to the receiver 10 aligns the arm 61 of the sear with the slot 64 in the receiver 10 for movement into and out of the path to the forward end of the breech block part 19.

Depending from the bottom wall of the trigger casing 65 is a U-shaped trigger guard 80 having end lugs 81 and 82 provided with countersunk holes to receive screws 83 and 84, respectively, which pass through suitably spaced holes in the casing bottom wall 66 and are threaded into the base plate 85 of an internal frame generally indicated at 85, whereby the two screws dependably clamp both trigger guard 80 and the internal frame 85 to the casing structure. The base plate 85 fits snugly between the side casing walls 67 and 68 and overlies substantially the entire length of the bottom wall 66, thus strengthening and reinforcing the latter. The base plate 85 and the bottom casing wall 66 have registering slots (Figures 1 and 5) downwardly through which extends the finger lever 86 of a trigger structure designated generally by the reference character 87. At the upper end of the finger lever 86 the trigger structure 87 is pivotally mounted by a stud shaft in the form of a screw 88 (see Figure 5) which passes freely through the casing side wall 67 and has its threaded end threaded into the opposite side wall 68.

Spaced lengthwise along the frame plate 85* are two upstanding lugs 91 and 92 (Figure 1) of which lug 91 is taller than lug 92 in order to slidably support, in down ward and forward inclined relation, a rod 93 that is round in cross-section except at its forward end where it is square, as at 93 to be slidably received in a slot 92 in the lug 92; at its rear or left-hand end the rod 93 carries or has integrally formed therewith a head or anvil 94 which is round in cross-section and rests for sliding support in a correspondingly shaped hole 91 in the rear lug 91. About the rod 93 is a spring 95, one end of which abuts against the anvil 94 and the other abuts against the forward lug 92; this action is to bias the rod 93 rearwardly, or to the left in Figure 1. The squared forward or right-hand end 93 of rod 93 extends into a vertical central slot 61 in the lower lever arm 61 of the sear 61 to which it is pivotally connected by a cross-pin 96. The spring 95 thereby also biases the sear 61 in clockwise direction about the pivot 77.

Parts 9394, spring 95, sear 61, and cross-pin 96 can be assembled as a sub-assembly or sub-unit, head 94 slid into hole 91 squared end 93 slid down into slot 92, and pivot stud 77 then put in place.

The spring 95, which can be relatively light inasmuch as it operates upon the sear 61 through the relatively long lever arm 61 of the sear, tends to swing the upper sear arm 61 upwardly through the slot 64 and into the interior of the receiver 10; during the retrograde stroke of the de'scribed biasing action, urging the upper end of the sear arm 61 into engagement with the outer cylindrical wall of the breech block 19 and continues so to do until the block 19 by-passes the sear arm 61, whereupon the spring 95 in effect snaps the sear 61 further in clockwise direction to project the end of the sear arm 61 into the path of forward movement of the breech block 19. The extent to which the sear arm 61 can thus be projected into the path of the block 19 is limited by the coaction between the sear arm 61 and the bottom wall of the trigger casing 65 which is reinforced and strengthened by the frame base plate 85 such limiting action also limits and fixes the rearmost position that the head of anvil 94 can assume. The lower slotted end of the sear arm 61 is shaped and dimensioned to abut the part 85 flatwise, thus providing a large bearing area to take up the reaction when the forward end of the breech block 19 engages the sear arm 61 to hold the breech block and bolt structure 18 in the position shown in Figure 1 against the force of the compressed spring 22. The scar construction and mounting above described can thus dependably hold the bolt structure in retracted position and is well adapted to take up and withstand such minor mechanical shocks and also the force of the compressed spring 22 that may accompany its action in holding the bolt structure in retracted position; the construction of the sear permits positioning of its pivot 77 relatively close to the receiver 10, and stresses exerted on the sear by the bolt structure are distributed by the reactions upon the pivot pin 77 and the reactions between the lower sear arm 61 and the bottom wall against which it abuts.

The round cross-sectioned anvil 94, which may be made of any suitable wear-resistant metal, has a rear end face 94 of substantial vertical height, as indicated in Figure l, but less than the vertical dimension or diameter of the anvil 94 itself, the lower edge of the end face 94 being formed by a horizontal chord or line at which it merges through a small radius into a cam face 94 that has a substantially flat portion followed by a curved portion as shown in Figure 1.

With these end faces of the anvil 94 coact certain structural features of the trigger structure 87, which is better shown on a larger scale in Figure 9. The upper part of the trigger structure, which may be made out of relatively thick flat stock, is in effect an upstanding parallel-sided plate-like part 8'7 which extends rearwardly, or to the left, sufficiently so that its lower under edge 37 can and does overhang the double bottom wall 66-85 of the trigger casing 65 (see Figure l) to the left of the slot through which the finger lever 86 extends downwardly, thus to provide a stop to limit the extent of counterclockwise pivoting movement of the trigger structure 87 under the bias of a spring 99 shown in Figure l, and also to support, to the rear or left of the pivot 88, a pivot pin 100 which extends through a hole in the plate-like part 87; at its ends pin 100 pivotally supports the arms 101 and 1'01 of a U-shaped detent 101 whose cross-part 101 extends crosswise of the forward or right-hand end of the plate part 87 of the trigger structure. This cross-piece 101, as shown in Figure 1, is thus positioned with its forward or right-hand face or edge juxtaposed to the rear or left-hand face 94 of the anvil 94. The detent 101 can be made of relatively heavy flat stock and as viewed in Figures 1 and 9 it is biased in counter-clockwise direction by a spring 102 whose upper end is received in a recess 101 formed, as by drilling, in the underface of the crosspiece 101 and whose lower end is received in a recess 87 formed, as by drilling, in a forwardly-projecting part 87 of the plate part 87 of the trigger structure 87. Suitable means are provided to limit this biasing action of the spring 102, conveniently by a forwardly-projecting portion 87 at the upper forward end of the plate-like trigger part 87; as is clearly shown in Figures 1 and 9, part $7 projects over the cross-piece 101 of the detent 101 and as shown better in Figure 1 its forward face or edge is juxtaposed to-the face 94- of the anvil 94 but is spaced rearwardly therefrom by a materially greater distance than the spacing of the cross-piece 101 of the detent 101 from the anvil face 94. Since these parts, as is later explained, coact with each other to engage the anvil 94, they are preferably made of any suitable wear-resisting or hardened metal. The spring 99 (Figure 1) is anchored at its one end to a suitable ear provided in the base of the frame 85, and its other end is secured to the trigger structure 87 at a point above the pivot 88 and preferably is connected to the detent pivot pin 100; normally the spring 99 biases and holds the trigger structure 87 in counterclockwise direction to the extent limited by the engagement of the ledge 97 thereof with the frame base plate thus holding the finger lever 86 in foremost position and ready to be manually pulled rearwardly (to the left) to swing the trigger structure 87 in clockwise direction.

As above noted, detent 101 is U-shaped; its parallel arms 101 and 101 are neatly received between and, respectively, lie alongside the side walls 67 and 68 (see Figure 5), adequate clearance being provided to insure freedom and ease of both movement of translation of the detent 101 as the trigger structure is pivoted about its pivot stud 88 and swinging movement of the detent 101 about its own pivot pin 100; the casing side walls 67 and 68 can act also to hold the pin 100 against material axial displacement.

Preferably the upper left portion of trigger part 87- is milled out as is better shown at 87 in Figure 9, in effect giving it a U-shaped horizontal cross-section by whose arms or side walls is supported the pivot pin 100 and between which extends the upper end of the spring 99 for linking to the pin 100.

The cross-piece 101 of the detent 101 (see Figure 9) has a forward contact part which is a blunt edge or narrow horizontal face 101 formed by a beveling or tapering off of the cross-piece 101 to form also an upper cam face 101 which thus merges or terminates in the blunt contact edge 101 In the at-rest position of the parts of the trigger structure and with the bolt structure 18 held retracted by the sear 61, the parts occupy relative positions substantially as shown in Figure l; anvil 94 is in its rearmost position, fixed by the engagement of sear arm 61 with the casing bottom wall, and the narrow horizontal contact face 101 of the detent is juxtaposed to the lower horizontally-edged end face 94 of the anvil which, if desired, it can actually contact or engage in the at-rest position.

In actuating the finger lever 86 of the trigger structure the operator has a choice of two ranges of movement or pull of the trigger, according as he desires to fire a single shot only and hence put the gun mechanism through only a single cycle of injecting, firing, and ejecting strokes, or to fire a succession of shots in rapid sequence and hence to cause the gun automatically to repeat the justmentioned cycle as many times as desired.

To cause the gun to fire only a single shot the operator pulls the trigger at any desired speed only part-way of its complete range of possible clockwise movement; illustratively, the above-described parts may be so proportioned that for single fire the trigger is pulled only halfway of its complete range of possible swing. It has been found in practice that an operator quickly learns to control at will and dependably the part-way range of movement.

When the trigger lever 86 is pulled or swung only partway as above described, the front face 101 of the crosspiece 101 of the trigger detent 101 moves forwardly (to the right) and as a result it moves the anvil 94 forwardly by pushing against it just above the junction of the anvil face 94 with the flat part of face 94 which makes about a 90-degree angle. The front face of the detent cross-piece 101 is of small vertical dimension and its lower boundary line is at the start of the movement just about at the apex of this angle. -As movement continues the anvil 94 and its rod 93 are moved forwardly, that is,

to the right, and relative pivoting between trigger part 87 and detent 101 about the axis of the pin 100 takes place, bringing overhang 87 closer to cross-piece 101; through the pin connection 96 counter-clockwise swinging of the sear 61 commences and continues until the upper sear arm 61*, whose upper end may be a bit rounded over as shown in Figure 1, is depressed enough to release the breech block and bolt structure 18, thus to commence under the action of the stored energy in the compressed spring 22, a Single cycle as earlier above described. By the time the bolt structure is so released by the sear, the trigger structure has just about reached the limit of its intended range of movement for single-fire action, and concurrently the detent pivot 100 has become physically elevated and the detent cross-piece 101 (which is to the other side of the trigger pivot 88) has become depressed or lowered by overhanging trigger part 87 and moved downwardly along the anvil face 94 to bring it below the apex-like junction between face 94 and face 94 and thus cause cam face 101 to coact with that apex junction to cam the detent 101 clockwise against its biasing spring 102 underneath the fiat part of anvil face 94 This happens with a snap action. In this manner, though the trigger lever 86 be now held in its midway position or even slightly moved further, the anvilactuating trigger detent 101 is cammed out of the path of retrograde movement of the anvil 94 and rod 93; the spring 95 is thus freed to bias the sear 61 in clockwise direction to catch and hold the bolt structure 18 at substantially the end of its retrograde spring-compressing stroke, thus halting the gun mechanism at the end of a single cycle. Bolt spring 22, now compressed, acts through the sear-stopping engagement of sear arm 61 with the casing bottom wall to fix the rearmost position of the anvil 94, detent cross-piece 101 still being underneath the anvil 94.

Subsequent release of the finger lever 86 from this illustrative midway position lets the spring 99 swing the trigger structure 87 counter-clockwise to its at-rest position; during such swing the detent cross-piece 101 moves rearwardly and cams itself, under the action of its spring 102 and by the coaction of its cam face 101 and the anvil cam face 94*, back into its normal position juxtaposed to the rear end face 94 of the anvil 94, as shown in Figure 1. All is now ready for a subsequent actuation of the trigger.

For continuous and automatic repeat fire the operator gives the trigger structure 87 its full or complete range of swinging movement, a range which, desirably, is limited by the engagement of the finger lever 86 with the sear arm of the trigger guard 80. When this is done the trigger detent 101 pushed against the anvil face 94 as before, and as the movement continues and the detent 101 becomes more and more depressed by the overhang 87 as the latter tilts about the trigger axis 88, the detent cross-piece 101 again moves downwardly along and snaps off the anvil cam face 94 and its cam face 101 cams it underneath the anvil 94, but because the range of swing of the trigger structure and the tilting of these parts thereof that lie above the trigger pivot 88 are greater, the forwardly-projecting part 87 of the trigger structure is brought into engagement with the anvil face 94*" immediately after detent 101 has snapped off it and part 87 now holds the anvil 94 and its push rod 93 in forwardly-moved position, blocks it against materialretrograde movement, and thus maintains the upper sear arm 61 depressed so that it cannot catch and hold the bolt structure; the latter and coacting mechanism, therefore, have to operate in a succession of cycles, each cycle comprising cartridge injection, firing, and shell ejection.

Cyclic repetition continues for as long as the trigger structure 87 is held in maximum depressed or actuated position; release of the finger lever 86 during any one of such cycles swings the upper trigger structure part 87 rearwardly, or to the left in Figures 1 and 9, thus freeing the anvil 94 and push rod 93 for retrograde movement under the action of the spring 95 to thereby bias the sear 61 to catch and hold the bolt structure 18 at the end of the selected cycle; such manual release of the trigger structure effects a restoration of the trigger detent 101 to its normal position as shown in the drawings, whence the mechanism is again ready for selective firing according simply to the range of trigger movement to be elfected manually.

If desired, the operator may manually set a suitablestop to make sure that he does not pull the trigger beyond the single-fire range of movement and this feature, about to bedescribed, is of advantage in training personnel. For this purpose I provide in the thickened part of the rearmost vertical arm of the trigger guard 80, where it merges into the receiving lug 81, a stop member in the form of a suitably heavy lug 104 that is secured at right angles to a short shaft 105 pivotally carried in the arm of the trigger guard an outer extended and shouldered end 105 of the shaft 105 carries a thumb lever 106 by which the stop lug 104 may be swung into or out of the path of rearward swing of the finger lever 86 of the trigger structure 87.

Parts 104, 105, and 106 are assembled as a unit and as such are insertible into position on the trigger guard before the latter is secured to the trigger casing 65. The rear arm trigger guard 80 is milled out or recessed centrally as at 80 leaving two spaced side walls in one of which is a bearing hole 80 to receive the free end of shaft 105 and in the other is a companion bearing 80 slotted as shown to be open from above, thus to permit the stop lug 104 to slide through as the sub-unit is axially slid to enter the free end of shaft 105 into bearing hole 80*.

The slotted or open bearing 80 permits ease of drilling a hole 80 in which is inserted a spring 80 and to receive a ball 80 above the spring, both being held in place by the overlying shaft 105 when the latter is slid into place. Shaft 105 has two curved recesses 105 and 105, some-- what less than half-spherical in shape to coact alternatively with the ball 80 as the shaft is turned by the.- thumb lever 106 and thus to releasably hold the shaft in. either of two positions; in one of them, stop lug 104 is. housed in the recess 80 and thumb-piece 106 stands up: alongside and snugly against the trigger casing wall 68 whose bottom wall 66 overlies and just contacts the shouldered part 105 of the shaft 105 to hold the latter down in its curved bearing seat 80", and in the other position stop lug 104 stands displaced about degrees and is about horizontal (Figure l) with its end in the path of movement of trigger finger lever 86 while finger-piece 1 06 stands projected rearwardly of the trigger guardv where it can be easily and quickly engaged by a finger or the thumb to swing it upward and out of triggerlimiting position. Thus the shift from single-fire to automatic successive firing can be quickly achieved should the operator have chosen initially to set the trigger stop lug 104- to single-fire position.

The assembly of the trigger guard 80 to the casing, as by the screws 82 and 83 as above described, in eifect completes the assembly of the sub-unit 104, 105, and 106 and of spring 80 and ball 80 to the gun for thereby-the slotted or open bearing 80 is closed off and the underside of the bottom wall 66 of the trigger housing 65 prevents such swing of the shaft as is needed to align stop lug 104 with the slotted bearing 80; without such alignment the sub-unit 104, 105, and 106 cannot be slid out of its bearings.

The above-described sear and trigger mechanism makes possible, also, simple provision for locking the mechanism in a safety condition, that is, to lock it against firing should the trigger lever 86 be accidentally pulled. As above described, the bolt structure 18 is held in retraoted position and the spring 22 held in compressed condition by the sear 61 which through the widely-spaced pivot 77 and the abutting of its lower lever arm 61 against the trigger housing bottom wall, distributes the resultant stresses. Forwardly of the lower sear arm 61 and provided with suitable bearing holes in the parallel side walls 67 and 68 of the trigger casing 65, I provide a shaft or pin 110 (see Figure 1) provided with a thumb lever 111 secured thereto at one outer end of the shaft 110 so that the thumb lever 111 can be swung alongside and externally of one of the casing side walls, such as the side wall 68 (see Figure In between the casing side walls 67 and 68 the shaft 110 has secured to it a stop arm 112 which is shaped and dimensioned so that when swung by the shaft 110 in counter-clockwise direction (Figure 1), its squared-off end face engages the. forward front edge face of the lower sear arm 61 when the sear is in bolt-holding position, the frame plate 85. serving as a stop to limit the counter-clockwise movement of the stop arm 112. In that position of the stop arm 112 the thumb lever 111 may conveniently stand in upright position externally of the trigger casing, as indicated in Figure 1. In that position of the stop arm 112 the sear 61 is dependably locked against counter-clockwise swinging and thus the sear cannot be actuated until, by means of the thumb lever 111, the stop arm 112 is swung clockwise for about 90 degrees and out of, the path of actuating movement of the sear. Any suitable means, such as the friction of the parts, may be employed to hold the safety mechanism in its two positions of selective actuation.

The above-described selectively actuated trigger and sear mechanism is capable of embodiment in rugged and durable form Without detrimentally affecting either sensitiveness of actuation, control of selectivity, or smoothness and ease of operation of the gun under varying conditions of practical use. And where the gun construction also embodies features for air-floated and air-cushioned movement of the bolt structure as earlier above described, advantageous coactions can take place; for example, violent or detrimental jarring or jolting of the gun structure as a whole is avoided not only by the substantially air-floated movement of the relatively heavy bolt structure but also by the smoothness of control of changes in velocity of movement of the bolt structure during itsv successive strokes. For such reasons as these, also, sighting or aiming of the gun structure is greatly facilitated and better accuracy achieved. At the forward end of the gun barrel 12 is a front sight, indicated at 115 in Figure 1, and at the rear of the gun structure an adjustable rear sight 116. In so far as the trigger mechanism is concerned, these also may take any suitable form.

For example, the rear sight 116 (Figures 1 and 2) may, illustratively, comprise a disc-like part 117, provided with a sight hole 118, and is integrally formed or secured to a flat elongated part 119 having a front or right-hand face (Figure 1) that is flat so that it can rest against the smooth fiat face 38 at the rear of the heavy block part 38 that closes the rear end of the receiver (see also Figure 4). It is held assembled to the block part 38 by a U-shaped casing-like metal stamping 120 which is flanged, as at 120 and 120" (Figures 2 and 4), and with the flanges resting against the rear face 38 of the part 38, suitable screws 121 that pass through the flanges and are threaded into the block part 38, secure the part 120 in place to form a vertical channel or guideway in which the part 119 of the rear sight is snugly received. The parts are so assembled that the vertical axis of the part 119, with the sight hole 118 on that axis (see Figure 2), coincides witha vertical diameter of'the receiver.

The rear face of the sight part 119 is provided with a suitable number of suitably spaced transverse or hori* zontal slots 122 which, according to the manually selected vertical position of the rear sight 116 relative to' its channel or guideway, coact selectively-with a detent'123' 12 formed by bending over one end of a long leaf spring 124 that lies against the vertical wall of the part and whose lower end is anchored by a screw 125 (Fig' ures l and 2) to the block part 38. Screw 125 also passes through the casing part 12!) and aids in holding that assembled to the block part 38.

Accordingly, by grasping the part 117 of the sight 116 (Figures 1, and 2), the sight 116 may be given any desired vertical position in relation to the front sight 115, the spring detent 123 yielding out of any one slot 122 and snapping into the selected slot to thereafter releasably hold the sight in the selected position for the desired range.

Suitable means are provided to hold the bolt structure 18, during its strokes of movement within the receiver 16, against rotary movement in order to maintain the proper relationship between the ejector 30 (Figure l) and the slot 31 in the bolt 20; this means may comprise, as shown in Figure 7, two small guideways 127 and 128 that extend longitudinally in the exterior surface of the breech block part 19 and two elongated guide bars 129 and 130 mounted in the wall of the receiver 10 to project inwardly thereof for reception, respectively, into the guideways 127 and 128. The guide bars may be set into slots 129 and 131%, respectively, milled in the receiver wall and they may be secured therein in any suitable way, as by welding externally of the receiver 10. They may be relatively short.

Preferably the guideways 127 and 128 are equally spaced to either side of the vertical axis of the breech block part 19 so as to have minimum effect upon the dynamic balance of the bolt structure. They are preferably located not on a diameter of the breech block 19 but rather on a horizontal chord thereof, illustratively just above the horizontal diameter as seen in Figure 7, and the guide bars 129 and 139, of course, are similarly located in the receiver wall on a chord; this just-described relationship makes it impossible to insert the bolt structure 18 into the receiver 11} in a position rotated degrees, from the position shown in Figure 7 for in such case the guide bars 129 and 130 and guideways 127 and 128 would not register. Accordingly insertion can be effected only so that slot 31 is always aligned with ejector pin 30. The guideways 127' and 128 and the guide bars 129 and 130 are preferably made of relatively small crosssection and are respectively interfitted to provide an easy sliding fit; close manufacturing tolerances can here be departed. from where the centering action of air under pressure in the airways 35 and 62 is utilized as illustratively above described. The cross-sectional area of the annular airway 35 and that of the annularairway 62 is relatively large and the guideways 127, 128, substantially closed for air flow by the guide bars therein, need not in that respect affect the. air-cushioning action of these airways as above described. Moreover, the guide bars and guideways coact in any at-rest position of the bolt structure to restrict side-play between the bolt structure and the interior wall of the receiver 10 and can serve to hold the breech block part 19 of the bolt structure substantially coaxially with the receiver 10 and the tube part 37 in spite of the. relatively large radial dimensions of the two annular airways 62 and 35, and in thus maintaining-substantial concentricity'of the opposed cylindrical walls that form the annular airways 62 and 35 in at-rest positions, they serve-advantageously to pro-condition such airways for subsequent air-floating action on the moving parts.

Where the guide bars 129 and 130 are relatively short I prefer to position them in the receiver wall near the forward end of the breech block part 19 when the bolt structure 18 is in retracted position as shown in Figure 9; such a' location places them with their rnidpoints approximately at the vertical transverse plane throughthe center'of mass of the whole bolt structure 18, thus approximating a balancing support. The above-mentioned concentricity of the opposed cylindrical walls that form the annular air- ways 62 and 35 need not in the position of rest of the bolt structure 18 be geometrically perfect and a reasonable approximation thereto sufiices to pre-condition the parts in aid of the subsequent action of the air moving through these airways in providing quickly de pendable air-cushioning or air-floated movement of the bolt structure relative to the stationary parts. In the position of rest of the bolt structure 18 in which it is held by the sear 61, the actions of the spring 22 and the sear 61 on the bolt structure are in respective directions to tend to aid in this pre-conditioning action, for the line of action of spring 22, being coaxial with the bolt structure 18, is above the point (as seen in Figure 1) at which the breech block part 19 is contacted by the sear 61; the action of the spring 22, therefore, is to tend to tilt the bolt structure 18 about the just-mentioned point, acting clockwise as viewed in Figure l, and thus it tends to counteract the eifect of the weight of the left-hand portion of the breech block part 19, acting about a transverse axis through the midpoints of the guide bars 128, 129, to tend to tilt the bolt structure in counter-clockwise direction, particularly where the guide bars are of very short length. It is thus possible to substantially balance these opposing moments as will now be clear, and hence the guide bars can be made short.

The bolt structure 18 may be manually brought to its retracted position to be caught and held by the sear 61 and the spring 22 also compressed, by a suitable retractor that may comprise an L-shaped element 133 (see Figure 8) that has a long arm 133 that is of trapezoidal cross-v section; part 133 has a short arm 133' which projects downwardly into the receiver 10 and into the path of forward movement of the front end face of the breech block part 19. Arm 133 is held moveably in this position in that the elongated part 13.3 which has a thickness slightly less than that of the wall of receiver 10, is slidably received in a slot 135 in the receiver wall, the slot having inclined side walls to give it a trapezoidal cross-section smaller than that of the part 133 the latter is inserted into the slot from the inside of the receiver tube 10, the beveled orinclined edges of the part 133 and of the slot 135 holding it against movement radially outward and forming coacting guiding surfaces whereby the member 133 may be moved back and forth along the slot 135.

As is indicated in Fig. 8, the slot 135 is of such a length that the retractor part 133 has a stroke of movement greater than the stroke of movement of the bolt structure 18 and is so located that when the bolt part 20 is in forwardly-projected position as when it strikes a shell in the barrel 12, the retractor part 133* is positioned at the forward end of the slot 135 which brings the retractor part 133' well in advance of the foremost position of the front face of the breech block part 19,. The slot 135 extends rearwardly to a suificient extent so that sliding rearward movement of the part 133 brings the retractor part 133 into engagement with the breech block part 19 and moves the latter rearwardly against the action of spring 22 to a position appropriate to permit the sear 61 to catch and hold the breech block part 19 in a retracted position and hence in readiness for firing control by the trigger mechanism, as above described.

Desirably the slot 135 is maintained covered throughout its length and the member- 133 held in proper coacting relation to the slot 135 by means of an elongated cover plate 136 (Figures 7 and 8) which is of a width greater than that of the slot 135 and externally of the cover plate 136 is a finger-piece 137 with a base plate 138 that rests against the cover plate 136. The three parts 133*, 136, and 138 are secured or clamped together by any suitable means, as indicated at 140 in Figure 8.

In the forward position of the bolt structure the rear or left-hand portion of the cover plate 136 overlies and closes 011 the slot 135 and when the retractor part 133 is moved rearwardly by pushing on the finger-piece 137, the forward or right-hand part of the cover plate 136 14 comes into slot-closing position and thus the slots is maintained closed throughout the range of movement of the retractor part 133 the coaction of the part 133 with the walls of slot 135 maintaining the relatively long and narrow cover plate 136 always in covering alignment with the slot 135 As shown in Figure 1, shoulder 14 of part 11 is formed by the forward or right-hand portion of a tapered or frusto-conical bore or turning 142 whose smallest di ameter is greater than the diameter of the flange part F of a shell C so that that flange part can take up against the rear end face of the barrel 12, and its larger diameter is considerably less than the inside diameter of the receiver 10.

With this frusto-conical bore or mouth 142 coact the bolt 20 for cartridge injection and the ejector pin 31) for ejecting the emptied shell and flipping it laterally and downwardly through the extractor opening 29 above described. The discharge opening 29 is just to the rear (to the left, as viewed in Figure 1) of the tapered month 142 of the part 11 and just forwardly of the ejector pin 30 so that as the empty shell is tilted ofi the rapidly retracting bolt structure to swing downwardly and out of the discharge opening 29, the large end of the tapered mouth 142 insures large clearance for this tilting and flipping discharge movement of the shell and, moreover, provides such ample clearance so that various lengths. of shells may be employed in the cartridges that the gun. can handle.

For injecting a cartridge into the rear end of the barrek 12 there is a rectangular opening 144 (Figures 1 and 11) in the receiver wall 10 and suitably related to the mouthv of the tapered bore 142 and to the bolt 20 of the bolt structure 18 in retracted position. The opening 144 ispositioned laterally, as is better shown in Figure 11, and. may be provided with a rectangularly cross-sectionedv open-ended casing 145 which may be separately fabri-- cated and welded or otherwise secured to the receiver 10.. In cross-section the part 145 is dimensioned to receivea sheet metal magazine 146 (Figure 11) provided with a usual type of spring 147 acting upon a push plate 1481 which in turn acts upon a suitable number of cartridges- C to urge them in a direction toward the right as viewed in Figure 11, suitable means being provided to hold the inserted magazine 146 in such a position that its two opposed walls 149 and 156, made of any suitable spring sheet metal, are held so that their spaced ends just clearthe path of movement of the bolt 21 These two spring: end walls 149 and 150 hold the foremost one of the series of cartridges C in the magazine in a position indi-- cated at C in Figure 11, a position in which a portion. of the cartridge is actually in the path of forward move-- ment of the front end of the bolt 20.

As the bolt 20 moves forwardly at good velocity it strikes the projecting portion of the cartridge C and commences to impel it toward the barrel 12 (see Figure 1),. but any tendency of the impelled cartridge C to tilt is: counteracted immediately by the entry of the nose of theshell into the large mouth of the tapered bore 142 of the part 11 which thereupon guides the cartridge into the gun barrel, as above described.

The trigger mechanism and sear control provided by this invention will be seen to be strong and durable in construction, welli adapted to meet the conditions of hard practical use, is efiicient and dependable in its action and control, and otherwise meets the various objects hereto-- fore set forth and achieves many advantages in manu-- facture, maintenance, care, and use.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth or shown. in the accompanying drawings is to be interpreted as. illustrative and not in a limiting sense.

I claim:

1. A gun construction for automatic successive firing of projectiles having a reciprocable member operable in repeated cycles each comprising a forward stroke and a retrograde stroke, a sear having means mounting it for movement into and out of the path of said member for respectively holding and releasing said member, a push rod having a round cross-sectioned head at one end and having a pivotal connection at its other end with said sear, said head having a substantially flat end face shaped substantially like a segment of a circle and the head being cut away at its under side to form a cam-like portion terminating in the chord of said segment-shaped end face, spaced bearing means for slidably supporting said push rod comprising a cylindrical bearing through which said round cross-sectioned head extends and a bearing for the other end of the push rod, said last-mentioned bearing and said other end of the push rod having coacting parts to prevent rotary movement of said push rod and head and to maintain said segment-shaped end face and cut away under side portion of the head against rotational displacement, spring means for biasing said sear in holding direction and for biasing said head in a direction outwardly of its cylindrical bearing, a pivoted trigger structure comprising a unitary lever having a downwardly projecting lever arm forming a finger piece and having an upwardly projecting lever arm having a vertical edge face terminating adjacent said segment-shaped end face of the head, said edge face being cut away to provide a rigid integral element, said upwardly projecting lever arm pivotally carrying an element positioned in the cut away portion of said vertical edge with spring means biasing said second-mentioned element upwardly against said first-mentioned element projecting toward said head beyond said first-mentioned element and normally engaging said segment-shaped head end face and having an upper cam face adapted for coaction with the chord-like edge of said end face, whereby, to effect operation of said reciprocable member in only one cycle, the finger lever arm is moved throughout only part of its range of swing to press said second-mentioned element against said segment-shaped end face of said head and upon continued movement to push said rod and to slide said element downwardly toward the chord-like edge of the end face of said head and at its cam face to be cammed downwardly by said chord-like edge for accommodation thereof in said cut away under portion of said head and thereby free said push rod and sear for movement in holding direction and, to effect operation of said reciprocable member in repeated cycles, said finger lever arm is given greater range of movement to bring the other of said elements into pushing engagement with said head end face and to hold said head and push rod and sear against movement in holding direction.

2. A gun construction for automatic successive firing of projectiles having a reciprocable member operable in repeated cycles each comprising a forward stroke and a retrograde stroke, a scar having means pivotally mounting it for movement into and out of the path of said member for respectively holding and releasing said member, spring means for biasing said sear in holding direction, a member having mechanical connection with said sear for actuating the latter against said spring means, a movable part having means pivotally mounting it for movement toward said last-mentioned member and having a depending finger lever that is manually operable in a direction generally away from said last-mentioned member, said part carrying two spaced forwardly directed actuating elements engageable successively with said member upon movement toward the latter and having a slot in the rear face thereof, means pivotally mounting the foremost of said two elements for movement relative to said part and in a direction to disengage said member and comprising two arms integral with said foremost'mem'ber and extending rearwardly each to one'side'of said part and a pivot pin in the latter and bridging said slot and pivotally supporting the rear ends of said two arms, means responsive to partial movement of said part sufficient to effect releasing movement of said sear by actuation of said member by said foremost actuating element to disengage the latter from said member and free the latter and said sear for movement in holding direction, and a spring extending into said slot and coacting with said pin to bias said pivotally movable part in a direction opposed to the direction of finger pull on said finger lever.

3. A gun construction for automatic firing of projectiles having a reciprocable bolt operable in repeated cycles each comprising a forward stroke and a retrograde stroke, a scar coacting with said bolt and having spring means for biasing it in bolt-holding direction, a trigger having means mounting it for movement throughout 'a given range, and mechanism between said trigger and said sear providing two mechanical sear-actuating connections and operable to actuate said sear in bolt-releasing direction successively in response respectively to partial movement of said trigger and to movement thereof throughout its complete range, said mechanism including disconnectible mechanical connection means operating in response to said partial movement of said trigger to free said sear for movement in bolt-holding direction under the bias of said spring means, said gun construction being provided with a trigger guard having an arm that extends to the rear of said trigger, said arm having at its end means for mounting it in position, and a shaft having a finger lever and a trigger-stop element, said trigger guard arm having bearing means open in a face thereof for insertion thereinto of said shaft with said stop element movable into or out of the path of movement of the trigger upon rotary movement of said shaft, said shaft being held assembled to said trigger guard arm by the securing of the latter in position.

4. A gun construction as claimed in claim 3, in which said trigger guard arm is provided with a substantially centrally located vertical slot that opens in said face and also opens in the trigger guard arm face that faces toward said trigger, said slot intersecting said bearing means substantially centrally and thereby dividing the latter into two aligned spaced bearings, said trigger-stop element being integral with and projecting from substantially a mid-portion of said shaft and thereby receivable in said slot and said finger lever being integral with an end of said shaft and being receivable externally and at a side of said trigger guard.

5. A gun construction for automatic successive firing of projectiles having a receiver and a' reciprocable bolt structure therein operable in repeated cycles each comprising a forward stroke and a retrograde stroke, said receiver having an aperture, a trigger-and-sear sub-unit comprising a casing having a bottom wall and upstanding parallel side walls provided with means for securing it externally to said receiver in a position to close over said aperture, a sub-assembly comprising a lever-like sear having a push rod pivotally connected at one end thereof to an arm of said scar and having a head at the other end thereof, a coiled spring about said push rod for biasing said sear in bolt-holding direction, said casing having therein guide means into which said push rod with said coiled spring is insertible and having means for pivotally supporting said sear between said side walls, and a sub-unit comprising a trigger structure having a finger lever projecting through an aperture in said bottom wall and means supporting it for pivotal movement between said side walls, saidtrigger structure having, in the portion thereof within said casing, two means spaced substantially along an arc of swing thereof about the axis of said trigger structure for thereby actuating said push rod at the head thereof in response first to a part-way swing of said finger lever and then in response to completion of the range of swingof said finger'lever together with means operating in timed relation to said part-way 17 swing of said finger lever to efiect disconnection from said push rod and thereby permit said spring to move said scar into bolt-holding position.

6. A gun construction for automatic successive firing of projectiles having a reciprocable member operable in repeated cycles each comprising a forward stroke and a retrograde stroke, a scar coacting with said reciprocable member and having spring means for biasing it in boltholding direction and having a part for moving it in boltreleasing direction, and a control member for coaction with said part and having means mounting it for movement throughout a given range, said control member having two actuating elements spaced in the direction of the path of movement of said control member for actuating and releasing said part by one of said actuating elements in response first to a partial movement of said control member whereby to eifect operation of said reciprocable member in only one cycle and for actuating and holding said part by the other of said actuating elements in response to completion of the range of movement of said control member whereby to eflect operation of said reciprocable member in repeated cycles, said control member comprising a finger lever for actuating it and said construction having a finger lever guard with means detachably securing it in position relative to said finger lever, manually operable means for limiting at will the actuating movement of said finger lever to a range corresponding to aforesaid partial movement or" said control member, and means dependent upon the assemblage of said finger lever guard to said construction for supporting said last mentioned means in coacting relation to said finger lever whereby said finger lever movement limiting means may be readily removed by detaching the guard and then replacing the guard.

References Cited in the file of this patent UNITED STATES PATENTS 1,344,991 Cunningham June 29, 1920 1,743,472 Meyer Jan. 4, 1930 2,072,197 Bergmann Mar. 2, 1937 FOREIGN PATENTS 588,476 Germany Nov. 18, 1933 635,896 Germany Sept. 30, 1936 649,706 Germany Sept. 1, 1937

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