Self Aligning Gas System For Firearm

Abstract

A bolt-actuating gas system for a firearm comprising an annular gas chamber, an annular piston, and an annular piston sleeve loosely mounted on a tubular magazine wherein the piston sleeve includes a push rod loosely mounted on the sleeve for contacting the bolt assembly. The push rod contacts the bolt assembly but is not connected thereto so that when the piston is moved through its work stroke, the push rod drives against the bolt assembly to propel the latter toward its retired position. Furthermore, the bolt assembly can be manually retracted to its retired position without causing concurrent movement of the piston, sleeve and rod.

Parent Case Text

This application is a continuation-in-part of my co-pending application Ser. No. 763,566, filed September 30, 1968 now U.S. Pat. No. 3,568,564.

Description

This invention relates to a short stroke gas system for use in actuating the bolt assembly of a firearm, such as a shotgun, or the like.

Conventional gas operated shotguns have slide arms connecting the piston to the bolt slide so that movement of the piston results in movement of the bolt assembly. When this type of gun is opened by hand, that is to say when the bolt assembly is manually retracted to its retired position, the slide arms and piston move with the bolt assembly. As the gun gets dirty from repeated use, and as deposits form in the gas cylinder and on the piston, the gun breech becomes more difficult to manually open.

A further disadvantage attendent to conventional gas operated shotguns lies in the exposure of the elements housed in the receiver to combustion gases when the gun is fired. As previously noted, the conventional gas operated shotgun includes at least one, and generally two slide arms which are connected to the bolt assembly and which are also generally connected to the gas piston. Since the gas piston is positioned well forward on the gun, and the bolt assembly is rearward on the gun in the receiver, the slide arms are of considerable length. The length of the conventional slide arms renders them flexible and subject to measurable bowing when the compressive force of the piston is applied to one end of the slide arms when the gun is fired. In order to permit the slide arms to move freely through the front wall of the receiver without jamming during actuation of the action of the conventional shotgun, sizeable apertures are cut through the front wall of the receiver. While the large apertures permit the slide arms to move freely through the front wall of the receiver, these apertures expose the various mechanical assemblies which are housed in the receiver to contaminated combustion gases which blow out of the gas cylinder toward the receiver. Exposure to these combustion gases causes undesirable deposits of material to form in the receiver, thus requiring periodic cleaning to remove these deposits.

The gas system of this invention provides for a piston stroke which is shorter than the extent of movement of the bolt assembly during actuation of the latter. The gas system includes an annular bracket member mounted on the gun barrel and surrounding a portion of a tubular cartridge magazine, to define therewith an annular gas chamber. A ring shaped piston member is slidably mounted on the magazine and disposed in the gas chamber, and a light weight piston sleeve member is connected to the piston and loosely and slidably mounted on the magazine to extend toward the receiver. A rigid push rod is loosely mounted on the piston sleeve, the push rod extending rearward therefrom through an aperture in the front wall of the receiver to a position adjacent the bolt assembly. The rigidity of the rod permits the rod aperture to be only slightly larger than the outside diameter of the rod so that a snug, sliding fit is achieved. The achievement of a snug fit between the rod and the aperture helps in greatly reducing the amount of combustion gases blown into the receiver. The bracket member includes lateral vents for exhausting combustion gases away from the receiver to further aid in reducing the amount of combustion gases blown into the receiver. A spring is mounted to bias the push rod, piston sleeve, and piston toward the gas chamber. The push rod is not connected to the bolt assembly but is positioned next to the bolt assembly so that the rod is moved against the bolt assembly during the work stroke of the piston to begin movement of the bolt assembly toward its retired position after the gun is fired. The rod stops its rearward movement at the end of the work stroke of the piston, which occurs when the piston sleeve strikes the front face of the receiver, but the momentum imparted to the bolt assembly from the rod causes the bolt assembly to continue to move rearwardly to its retired position away from the rod. Thus the automatic actuation of the bolt assembly is accomplished without the use of slide arms, or the like, connected to the bolt, and with minimum exposure of the interior of the receiver to combustion gases. Also due to the fact that the push rod is not connected to the bolt assembly, it is readily apparent that the bolt assembly can be manually retracted to its retired position without causing concurrent movement of the piston and piston sleeve.

By loosely mounting the piston sleeve on the magazine, and further by loosely mounting the push rod on the sleeve, the system of the invention achieves a substantial degree of self alignment. The bracket is fixed to the barrel, the barrel fixed to the receiver, and the magazine is also fixed to the receiver in a conventional manner. Also the hole in the receiver through which the push rod moves is fixedly located with respect to the receiver. If the sleeve were snugly mounted on the magazine, and the push rod were rigidly secured to the sleeve, the system would only operate satisfactorily if the axes of the push rod, push rod hole, sleeve, and magazine were all parallel. By mounting the sleeve loosely on the magazine, a degree of lateral movement is permitted between the sleeve and magazine; and by mounting the push rod loosely on the sleeve, a further degree of lateral movement between the push rod and sleeve is permitted. In this way, a large degree of lateral flexibility is imparted to the system and the axis of the push rod hole does not have to be parallel to the axis of the magazine to insure that the system operates smoothly and dependably. Substantial manufacturing cost savings are thus realized and scrap is greatly reduced with the system of this invention.

It is, therefore, an object of this invention to provide a gas system for actuation of a bolt assembly in a semi-automatic shotgun, which gas system has a short stroke.

It is a further object of this invention to provide a gas system of the character described wherein the bolt assembly is unconnected to the bolt-actuating portion of the gas system.

It is yet another object of this invention to provide a gas system of the character described wherein the interior of the receiver portion of the gun is effectively sealed against penetration of gases from the gas chamber.

Yet another object of this invention is to provide a system of the character described having inherent lateral flexibility between moving parts and fixed parts in the system.

Other objects, advantages and features of the invention will become apparent to one skilled in the art from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation of a portion of a shotgun with parts removed for clarity, with the bolt assembly of the gun and the various components of the gas system disposed in their respective normal positions prior to firing the gun;

FIG. 2 is a side elevation of a portion of a shotgun similar to FIG. 1, with the bolt assembly of the gun and the various movable components of the gas system disposed in their respective positions after the gun has been fired and the bolt assembly driven to its retired position;

FIG. 3 is a vertical sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is an exploded perspective view of the piston sleeve, push rod guide, push rod, and spring showing details of a preferred configuration of the push rod guide which provides a loose connection between the push rod and piston sleeve; and

FIG. 5 is a vertical sectional view of the gas system of this invention taken generally along line 5--5 of FIG. 3 and particularly showing the looseness of the connections between the push rod and sleeve, and the sleeve and magazine.

Referring now to FIGS. 1 and 5, a preferred embodiment of gas system of this invention is shown. The system includes a conventional tubular magazine 2 which is rigidly mounted in any known manner beneath and parallel to the barrel of a shotgun. The forward end of the magazine 2 is threaded to receive an end closure cap 6. An annular bracket member 8 is mounted on the magazine 2, the bracket 8 having first bore 10 of a predetermined smaller diameter which is snugly fitted against the outside surface of the magazine 2. The bracket 8 also includes a second bore 12 of a predetermined larger diameter which is spaced apart from the outside surface of the magazine 2 to define therewith a gas chamber 52. A plurality of lateral gas vents 14 are disposed in the wall of the bracket 8 in communication with the second bore 12. A laterally directed gas bleed port 16 is drilled through the wall of the bracket 8 to communicate with the second bore 12 at a location adjacent to the first bore 10. An oblique, radial wall 11 is interposed between the two bracket bores 10 and 12.

An annular piston member 18 having a first smaller bore 20 and a second larger bore 22 is slidably mounted on the magazine 2. An oblique face 24 is interposed between the bores 20 and 22, the face 24 preferably being formed at an angle of about 30.degree. with the vertical. A pair of split rings 26 are mounted on the exterior of the piston 18 for gas sealing engagement with the larger bracket bore 12. A split ring 28 having an obliquely cut end face 30 and a normally cut face 32 is disposed within the piston bore 22, the face 30 being contiguous with the oblique piston face 24. A split metal ring 13 is mounted on the magazine 2 and is positioned at the forward end of the gas chamber 52. The ring 13 has an obliquely cut forward end wall 15 which bears against the oblique bracket wall 11 so that when the walls 15 and 11 are moved against each other, the ring 13 will be squeezed down onto the magazine 2 to form a gas obturating seal therewith. The rearward face 17 of the ring 13 is concavely arcuate and is positioned adjacent to the bleed port 16.

A lightweight annular piston sleeve 34 is loosely and slidably mounted on the magazine 2 and extends into the bore 22 of the piston 18. The inner end 36 of the sleeve 34 is adjacent to the normal face 32 of the ring 28. A rigid push rod 38 is loosely connected to the sleeve 34 in the following manner. A push rod guide member 31 in the form of a curved plate is secured to the piston sleeve 34 with the wall of the guide 31 being spaced apart from the exterior of the sleeve 34 to combine therewith to form a well 33. The push rod 38 is formed with a radially enlarged shoulder 39 which subdivides the rod 38 into a forward portion 41 and a rearward portion 43. The forward portion 41 of the rod 38 is disposed in the well 33, with the diameter of the rod portion 41 being sufficiently small so as to permit substantial lateral movement of the rod 38 with respect to the guide 31. A compressible spring 40 is mounted on the rod 38, the spring bearing against the front wall of the receiver on one hand, and bearing against one end wall of the push rod shoulder 39 on the other hand. Thus the spring 40 urges the rod portion 41 into the well 33 while at the same time provides sufficient flexibility to permit the rod 38 to move laterally with respect to the guide 31 and sleeve 34. With particular reference to FIG. 5, it will be noted that the piston sleeve 34 has a bore with a sufficiently large diameter so as to be very loosely fitted over the magazine 2, there being a noticeable gap 3 between the magazine exterior and the sleeve interior. Thus the sleeve 34 is free to move laterally with respect to the magazine 2, which lateral movement is thereby imparted to the rod guide 31.

Referring now to FIG. 5, the gas system of FIG. 1 is shown mounted on a shotgun (only partially shown). The bracket 8 is mounted below the gun barrel 46, and a port 48 is drilled through the barrel 46 into the barrel bore 50. The port 48 is aligned with the gas bleed port 16 to provide a passage through which pressurized combustion gases are bled from the bore 50 into the gas chamber 52. It is noted that bracket 8, piston 18, piston sleeve 34, and magazine 2 can all be disposed within a forearm (not shown) mounted on the barrel 46. The magazine 2 is rigidly connected in any conventional manner to the receiver 56 of the shotgun. The bolt slide 58 is shown in FIG. 5 in the bolt assembly's battery position. The remaining portions of the bolt assembly are omitted for purposes of clarity, it being understood that the bolt may take any conventional form. It is further understood that the bolt assembly is biased by a spring 54 toward the battery position in a conventional manner (see FIG. 1). The push rod 38 extends through an aperture 60 in the front wall 62 of the receiver 56. It is to be understood that the diameter of the aperture 60 is preferably only about 0.003 in. larger than the diameter of the rod 38 so as to provide a snug gas sealing fit. The left hand end of the rod 38, as viewed in FIG. 5 is contiguous with the front face of the bolt slide 58. The bolt slide 58 is mounted for reciprocal movement on a pair of rails (not shown) in the receiver 56 in a conventional manner.

FIG. 3 shows the radial position of the barrel 46, the push rod aperture 60 and the magazine 2. Once the gun is assembled, the locations of these three elements are fixed with respect to each other, and with the prior art systems, great care must be taken to insure that the axes of the magazine 2 and the hole 60 are parallel to each other so that the moving parts of the system can operate freely and without binding.

FIG. 2 shows the actuating positions of the various members of the gas system when a shot charge is fired from the gun and the shot charge (not shown) is propelled down the barrel bore to a position downstream of the aligned gas bleed ports 16 and 48. High pressure combustion gases are bled through the ports 16 and 48 into the gas chamber 52. These high pressure gases cause the piston 18 to move through the bracket bore 12 toward the receiver 56, thus driving the piston sleeve 34 and rod 38. These high pressure gases further act upon the curved face 17 of the ring 13 to squeeze the latter tightly about the magazine 2 thereby effectively sealing the forward end of the gas chamber 52 against leakage of gases. The end point of the work stroke of the piston 18 is reached when the piston sleeve 34 strikes the front wall 62 of the receiver 56, this position being shown in FIG. 2. It is noted that the spring 40 is compressed during the driving stroke of the piston 18. Movement of the piston 18 to the end point of its work stroke uncovers the gas vents 14 so as to vent the high pressure gases laterally out of the gas chamber 52 to lower the pressure therein.

As the piston 18 is driven through its work stroke, the split ring 28 flexes radially inwardly against the magazine 2, the flexure resulting from the angular interface between the ring 28 and the piston face 24. The ring 28 thus provides a gas tight seal between the piston 18 and the magazine 2, and also serves to scrape the magazine clean of any deposits during the work stroke of the piston. On the return stroke of the piston 18; the resiliency of the ring 28 causes it to flex back to its normal loose fit about the magazine 2, thus offering little or no impedance to the returning of the piston to its original position.

As previously noted, the mass of the bolt slide 58 is such that the bolt slide acts as an inertial body for the bolt assembly. Movement of the bolt assembly from the battery position to the position shown in FIG. 2 results from momentum imparted to the bolt assembly by the push rod 38 being moved to the rear during the work stroke of the piston, even though the push rod 38 ceases its rearward movement at the position shown in FIG. 2. It is also noted that the piston 18 does not completely leave the gas chamber 52 at any time during its work stroke, thus no problem is encountered in returning the piston to its forward position, such as would otherwise be encountered if the piston 18 were driven completely out of the chamber and then forced to re-enter the chamber, in which case the piston 18 could easily get hung up on the bracket wall.

Since the various moving components of the system, such as the piston sleeve 34, and push rod 38 are free for a significant degree of lateral movement as they are moved longitudinally during actuation of the system, the system becomes self aligning in various stages of its actuation. Since the sleeve 34 can move laterally, the exterior of the magazine 2 over which the sleeve 34 slides can include various imperfections such as depressions and high spots, and it need not be a perfect cylinder with walls perfectly parallel to its axis at all points. The sleeve 34 will simply slide over any imperfections adjusting itself laterally as it slides, and will not bind up on the magazine by having its axis angularly displaced with respect to the axis of the magazine. At the same time the push rod 38 will be moved through a rather snugly fitting aperture 60, however the axis of the aperture will not have to be closely parallel to the axis of the sleeve 34 because the rod 38 can move laterally with respect to the sleeve axis. Thus any change in the attitude of the axis of the sleeve or rod which may occur during longitudinal movement of these elements will not cause the system to bind up, as would otherwise be the case were these elements tightly connected to each other.

When the pressure in the gas chamber 52 has been sufficiently lowered, the spring 40 acts to return the piston 18, piston sleeve 34 and rod 38 to their original positions (shown in FIG. 1.)

It will be readily appreciated from the preceding that the gas system of this invention permits a short piston stroke, while at the same time provides for proper automatic actuation of the bolt assembly of the firearm. Furthermore, it is readily apparent that the bolt assembly in a gun incorporating the gas system of this invention can be manually retracted to its retired position without concurrent movement of the piston, sleeve, or rod occurring. The provision of a rigid push rod and gas vents in the gas system also presents a cleanly operating assembly hitherto unattainable in the gas systems of the prior art. Still further, the loose connections between the piston sleeve and magazine, and between the push rod and piston sleeve permit the system to align itself as it moves longitudinally during actuation and prevents binding of the elements during actuation.

Since many changes and variations of the disclosed embodiment of the invention may be made without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.

Claims

What is claimed is:

1. In a gas-operated system for actuating the bolt assembly in a firearm having a receiver with a front wall, a barrel secured to the receiver, and a tubular magazine secured to the receiver and generally parallel to the barrel and comprising:

a. a bracket secured to the barrel and surrounding the magazine to form therewith an annular gas chamber;

b. a gas bleed port extending between said gas chamber and a bore in the barrel;

c. an annular piston movably mounted on the magazine and disposed in said gas chamber;

d. sleeve means slidably mounted on the magazine and drivingly engaging said piston; and

e. push rod means loosely connected to said sleeve means, said push rod means being in buttment with the bolt assembly but free of securement therewith, and said push rod means extending through an aperture in the front wall of the receiver said push rod means being sized to form a gas obturating fit with the receiver front wall aperture, and said push rod means being laterally movable with respect to the sleeve means axis and the bolt assembly.

2. The gas-operated system of claim 1, wherein said sleeve means is loosely mounted on the magazine so as to permit lateral movement of the sleeve means to occur with respect to the magazine axis.

3. The gas-operated system of claim 1, further comprising at least one gas vent in said bracket, said gas vent being uncovered when said piston is in a driven position.

4. The gas-operated system of claim 1, further comprising spring means mounted on said push rod means in engagement with the front wall of the receiver, said spring means being operable to return said push rod means, said sleeve means, and said piston from a driven position to a normal position forwardly spaced from said driven position.

5. The gas-operated system of claim 1, further comprising a split metal gas obturating ring mounted on the magazine and positioned in a forward end of said gas chamber, said ring having a curvilinerar surface disposed adjacent to said gas bleed port, said curvilinear surface being acted upon by high pressure gases emitted from said gas bleed port to compress said ring tightly onto the magazine to form a gas obturating seal therewith.

6. In a gas-operated system for actuating the bolt assembly in a firearm having a receiver with a front wall, a barrel secured to the receiver, and a tubular magazine secured to the receiver and generally parallel to the barrel, and comprising:

a. a bracket secured to the barrel and surrounding the magazine to form therewith an annular gas chamber;

b. means forming a gas obturating seal at the forward end of said gas chamber;

c. a gas bleed port extending between said gas chamber and a bore in the barrel;

d. an annular piston movably mounted on the magazine and disposed in said gas chamber;

e. sleeve means drivably connected to said piston and slidably and loosely mounted on the magazine, said sleeve means being free for substantial lateral movement with respect to the magazine axis;

f. the receiver front wall having an aperture aligned with the bolt assembly;

g. guide means secured to said sleeve means and forming therewith a well of predetermined lateral dimension;

h. push rod means having a first portion disposed in said well, said first portion having a lateral dimension substantially smaller than the lateral dimension of said well to permit said push rod means to undergo substantial lateral movement with respect to said guide means and said sleeve means, and said push rod means having a second portion extending through said receiver front wall aperture to form a gas obturating seal therewith; and

i. spring means mounted on said push rod means and in engagement therewith, said spring means further engaging said receiver front wall to bias said push rod, said sleeve, and said piston toward a forward normal position.