Slide Guide For Rifles

Abstract

A gas operated auto-loading rifle having a longitudinally reciprocating slide connected to and operating the breech bolt of the rifle is provided with slide guide means that prevents significant lateral and vertical movement of the slide during its to-and-fro longitudinal travel and also insures proper positioning of the slide block with respect to the gas pipe of the rifle barrel when the slide is at its forwardmost position. The slide guide comprises a channel-shaped member that extends along the slide from adjacent the gas pipe to adjacent the receiver, the bottom wall and upstanding side walls of the channel-shaped member being disposed in close proximity to the bottom and side surfaces of the slide block. Means are provided for securing the forward end of the channel-shaped member to the barrel in position relative to the gas pipe to insure that the slide block and the gas pipe are disposed in cooperating operational relationship when the slide is at its forward position, and means are provided for securing the rearward end of the channel-shaped member at the receiver. The channel-shaped member serves to guide the reciprocating slide block and to protect and reinforce the forearm of the stock of the rifle.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to gas operated auto-loading rifles.

2. The Prior Art

Gas operated auto-loading rifles of the type to which the present invention relates have a barrel, a receiver on which the barrel is mounted, a breech bolt mounted in the receiver behind the barrel, a trigger and related parts, a magazine, and a mechanism actuated by powder combustion gases when the rifle is fired which operates the bolt to extract and eject the spent cartridge case and to insert a fresh cartridge in the chamber of the rifle barrel. A gas pipe is disposed below the barrel generally parallel thereto, and the barrel is formed with a gas port that communicates with the bore and with the gas pipe so that powder gases from the bore are directed to the gas-actuated bolt operating mechanism associated with the gas pipe. The mechanism for operating the bolt comprises a longitudinally movable slide having a slide handle portion that is connected to the bolt and a slide block portion that is disposed adjacent the gas pipe when the slide spring moves the slide to its forward position. When the slide is at its forward position, the slide block is in position to be acted upon, directly or indirectly, by the powder gases entering the gas pipe when the rifle is fired so as to drive the slide rearwardly against the compression of the slide spring and thus operate the bolt in the manner described.

The slide moves longitudinally at great speed to its rearward position and then to its forward position when the rifle is fired, and malfunctioning and damage to the mechanism will occur unless the high speed reciprocating travel of the slide, and in particular the slide block, is contained and controlled. In conventional auto-loading rifles of the type to which the invention relates the slide block is provided with slide block guide means for guiding the slide block as it travels between the gas pipe and the receiver of the rifle. The slide block guide usually comprises a longitudinally disposed rod or similar member which extends through a longitudinal hole formed in the slide block, the guide rod being secured at its forward end to the gas block on which the gas pipe is mounted and at its rearward end to the receiver of the rifle. As the slide guide rod and the gas pipe cannot occupy the same area or space they must be vertically spaced from one another, and the slide block must have sufficient vertical depth to accommodate the correspondingly vertically spaced slide guide rod hole. This, in turn, means that the stock forearm in which the slide block and slide guide rod are received must be bulky enough and deep enough to accommodate these deep and bulky parts.

The inherent bulkiness of the stock forearm of conventional medium caliber automatic rifles (for example, the .30 caliber M14 rifle) is not objectional as it is in correct proportion to the size of the other components of these relatively large rifles. However, when it is desired to build a smaller and lighter "scaled down" automatic rifle that fires smaller caliber high power ammunition (say, .223 caliber ammunition), the inherent bulkiness of the stock forearm required by the slide block and slide guide rod results in a rifle the proportions and handling characteristics of which make the rifle unacceptable to most shooters. As a result of an extensive investigation into the problems involved in the design and manufacture of a reliable "scaled down" automatic rifle for small caliber high power ammunition having acceptable proportions and handling characteristics, we have now devised an improved slide guide for the slide block of such rifles which eliminates the bulky guide rod of conventional rifles while providing added protection and reinforcement to the stock forearm.

SUMMARY OF THE INVENTION

The improved slide guide means of the invention is applicable to the previously described type of gas operated autoloading rifle having a slide which is acted upon, directly or indirectly, by powder gases entering gas gas pipe of the rifle when the rifle is fired so as to drive the slide rearwardly against the compression of the slide spring and thus operate the bolt in the manner described. Basically, the slide guide means comprises an elongated generally channel-shaped member that extends along the slide from adjacent the gas pipe to adjacent the receiver of the rifle, the bottom wall and upstanding side walls of the channel-shaped member being disposed in close proximity to the bottom and side surfaces of the slide block to prevent significant lateral or vertical movement while permitting longitudinal movement of the slide block. Means are provided for securing the forward end of the channel-shaped member to the barrel in position relative to the gas pipe to insure that the coacting slide drive means associated with the slide block and the gas pipe are disposed in operational relationship when the slide is moved to its forward position, and means are provided for securing the rearward end of the channel-shaped member to the rifle at the receiver. Advantageously, the slide block is provided with a pair of upper guide ears that extend upwardly on opposite sides of the slide block in close proximity to the opposite side surfaces of the barrel to prevent significant lateral movement of the upper part of the slide block as it moves longitudinally with respect to the barrel.

The rifle usually is provided with a stock and stock forearm, the forearm being formed with a channel-shaped longitudinal recess in which the channel-shaped slide guide member is received, the slide guide member thus serving as a liner that protects and reinforces the forearm. A U-shaped end cap is advantageously secured to the forward end of the channel-shaped slide guide member, the forward end of the slide guide member and the end cap defining a rearward facing U-shaped recess in which the forward end of the forearm is received. The gas pipe is usually mounted on a gas block that is secured to the barrel, the gas block advantageously being provided with rearwardly extending slide guide locating lugs and with a rearwardly extending locating ledge that is disposed radially outwardly with respect to said locating lugs, the locating lugs and the locating ledge of the gas block engaging and positioning the forward end of the slide guide member accurately with respect to the gas pipe. Other structural features and advantages of our new slide guide means will be apparent from the following detailed description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The slide guide means of the invention will be better understood from the following description thereof in conjunction with the accompanying drawings of which:

FIG. 1 is a fragmentary side elevation of an auto-loading rifle embodying the invention,

FIG. 2 is a sectional view along the vertical plane intersecting the longitudinal center line of the forearm portion of the rifle of FIG. 1 showing an advantageous form of coacting slide drive means in which the gas pipe is provided with a stationary piston portion that is received in a forward facing gas chamber formed in the slide block,

FIG. 3 is an exploded perspective view of the forearm and gas block portions of the rifle of FIG. 2,

FIG. 4 is a sectional view along line 4--4 of FIG. 2,

FIG. 5 is a sectional view along line 5--5 of FIG. 2,

FIG. 6 is a sectional view along line 6--6 of FIG. 2,

FIG. 7 is a sectional view along line 7--7 of FIG. 2.

FIG. 8 is a fragmentary sectional view similar to FIG. 2 showing another advantageous form of coacting slide drive means in which a longitudinally movable piston is disposed in the gas pipe, the movable piston having a rearward extension that contacts the slide block, and

FIG. 9 is a fragmentary sectional view similar to FIG. 2 showing yet another advantageous form of coacting slide drive means in which a longitudinally movable piston is disposed in the gas pipe, the slide block having a forward extension that contacts the movable piston.

DETAILED DESCRIPTION

As shown best in FIG. 1, the principal externally visible components of a typical gas operated auto-loading rifle to which the present invention relates include a barrel 10, a receiver 11 to which the barrel is secured, a longitudinally movable bolt 12 mounted in the receiver 11 behind the barrel 10, a longitudinally movable slide 13 having a slide cocking handle 14 that is connected to the bolt 12, a trigger 16 for operating the firing mechanism (not shown), a magazine latch 17, a stock 18 having a stock forearm 19, a forearm upper hand guard 20, a gas block 21 having a block clamp portion 22, and a rear sight 23. The stock 18 is formed with a vertical slot or cutout portion (not shown) in which the firing mechanism associated with the trigger 16 and the magazine associated with the magazine latch 17 are received, the vertical slot in the stock 18 being provided with a stock reinforcing lining 24 (a fragment of which is shown in FIG. 2) that fits in and lines the slot, thereby protecting and reinforcing the stock in this area.

In the embodiment shown in FIG. 2, the barrel 10 is formed with a gas port 25 which communicates with the bore 26 of the barrel and with a gas passageway 27 formed in the gas block 21. A gas port bushing 28 is disposed between the gas port 25 and the gas passageway 27, and a rearward facing gas pipe 29 of relatively small diameter is secured to the gas block 21 in communication with the gas passageway 27 thereof. The gas port bushing 28 is received in matching recesses formed in the barrel 10 and the gas block 21, and the block clamp 22 is securely fastened to the gas block 21, thereby insuring permanent alignment of the gas passageways of the gas port, the port bushing and the gas block. In both of the embodiments shown in FIGS. 8 and 9 the gas pipe 30 is mounted on the gas block 21 and is of relatively large diameter so that a longitudinally movable piston may be disposed within the gas pipe as hereinafter described. The gas port bushing 28 extends through a snug hole formed in the gas block 21 and is received in matching recesses formed in the barrel 10 and the gas pipe 30, thereby insuring permanent alignment of the gas passageways of the gas port, the port bushing and the gas pipe 30. In all embodiments the gas pipes 29 and 30 are disposed below the barrel 10 generally parallel to the bore or the longitudinal axis of the barrel. The forward end of the gas pipe 29 is effectively closed off by the gas block 21 in the embodiment shown in FIG. 2, and the forward end of the gas pipes 30 are effectively closed off by the screw plugs 31 in the embodiments shown in FIGS. 8 and 9. The rearward ends of the gas pipes are provided with openings the function of which is hereinafter explained.

The bolt 12 may be of any of the known types that are operated by a gas powered reciprocating slide mechanism, and advantageously it is a modified M14 type action as shown in FIG. 1. The slide 13 has an external cocking handle 14 that, as noted, is operatably connected to the bolt 12 and an internal slide block 32 (shown best in FIG. 2) that is disposed beneath the barrel 10 within the stock forearm 19, the external and internal portions of the slide 13 being securely fastened together at junction point 33. Thus, when the slide block 32 moves longitudinally from its forward position to its rearward position and return, the bolt 12 is caused to reciprocate in like manner. A slide spring 34 is provided for urging the longitudinally movable slide 13 toward its forward position, the rearward portion of the spring 34 being mounted on the spring guide rod 35 secured to the receiver 11 and the forward portion thereof being received in the longitudinally elongated spring receiving recess 36 formed in the slide block 32. Coacting slide drive means are associated with the gas pipe and with the slide block 32, the slide drive means driving or propelling the slide 13 rearwardly against the compression of the slide spring 34 when powder combustion gases enter the gas pipe through the gas port 25. Thus, in the embodiment shown in FIG. 2 the rearward end of the gas pipe 29 is provided with a rearward facing stationary piston portion 37 having a longitudinal hole extending therethrough, and the slide block 32 is formed with a forward facing gas chamber 39 in which the rearward facing piston portion 37 of the gas pipe 29 is received when the slide 13 is at its forwardmost position. When the rifle is fired, the slide 13 is propelled rearwardly by the action of powder combustion gases from the gas pipe 29 against the slide block 32 and then forwardly by the pressure of the slide spring 34 against the slide block 32, the reciprocating travel of the slide 13 operating the bolt 12 to extract and eject the spent cartridge case and to insert a fresh cartridge in the chamber 40 of the rifle barrel 10.

As shown best in FIGS. 2 and 3, the improved slide guide of the invention comprises an elongated channel-shaped member 42 that extends along the slide 13 from adjacent the gas pipe 29 to adjacent the receiver 11. The bottom wall 43 and the upwardly extending side walls 44 and 45 of the channel-shaped member 42 are disposed in close proximity to the corresponding bottom and side surfaces of the slide block 32, as shown in FIGS. 5 and 6, so as to prevent significant vertical or lateral movement while permitting free longitudinal movement of the slide block 32. In the preferred embodiment, the bottom wall 43 of the channel-shaped member 42 is provided with a longitudinal rib 43a disposed on the inner surface thereof on which the slide block 32 rides, and the side walls 44 and 45 are provided with longitudinal ribs 44a and 45a disposed on the inner surfaces thereof in virtual contact with the corresponding side surfaces of the slide block 32, as shown best in FIG. 6. In addition, as shown in FIGS. 5 and 6, the slide block 32 is advantageously provided with a pair of upper guide ears 46 and 47 which extend upwardly on opposite sides of the slide block in close proximity to the corresponding side surfaces of the barrel 10, thereby helping prevent unwanted lateral movement or wobble of the slide block as it travels longitudinally to-and-fro beneath the barrel 10. Thus, when the channel-shaped member 42 is correctly positioned and secured in place beneath the barrel 10, the rapid reciprocating travel of the slide block 32 is contained and controlled with consequent improved reliability of and reduced wear and tear on the autoloading mechanism.

Means are provided for securing the forward end of the channel-shaped member 42 to the barrel 10 in position relative to the gas pipe to insure that the coacting slide drive means of the slide and the gas pipe are disposed in opertional relationship adjacent each other (and specifically in the embodiment shown in FIG. 2 that the piston portion 37 of the gas pipe 29 is received in the gas chamber 38 of the slide block 32) when the slide is moved to its forward position, and means are also provided for securing the rearward end of the channel-shaped member at the receiver.

In the preferred embodiment shown in the drawings, the means for securing and positioning the forward end of the channel-shaped member 42 relative to the barrel 10 advantageously includes a U-shaped end cap 48 that is secured to the forward end of the channel-shaped member 42, advantageously by means of the three radially extending cap fastening tabs 50 of the member 42 and the two longitudinally extending guide fastening tabs 51 of the end cap 48. As shown best in FIG. 3, the gas block 21 is provided with three rearwardly extending slide guide locating lugs 53 and with a rearwardly extending U-shaped locating ledge 54 disposed radially outwardly with respect to the locating lugs 53. As shown best in FIG. 4, the locating lugs 53 are positioned to engage the inner peripheral surface of the channel-shaped member 42 and the locating ledge 54 is positioned to engage the outer peripheral surface of the U-shaped end cap 48, thereby securing the forward end of the slide guide to the barrel 10 in its correct position relative to the gas pipe as shown in FIGS. 2 and 5. Also in the preferred embodiment, the means for securing and positioning the rearward end of the channel-shaped member 42 at the receiver 11 comprises a rearward extension 56 of the channel-shaped member 42 by means of which the slide guide is secured in place at the receiver 11. In this embodiment, as shown best in FIG. 2, the stock reinforcing liner 24 is provided with a forwardly extending slide guide extension retaining lip 57 that engages the rearward extension 56 of the channel-shaped member 42 and secures it in place against the stock 18. Moreover, as shown best in FIG. 7, the receiver 11 is advantageously formed with an extension receiving recess 58 in which the rearward extension 56 of the channel-shaped member 42 and the extension retaining lip 57 of the liner 24 are received, the stock 18 holding the retaining lip 57 and the rearward extension 56 in place in the recess 58. Advantageously, the lateral dimension or width of the rearward extension 56 is approximately the same as the lateral dimension of the recess 58 so that lateral movement of slide guide relative to the receiver is prevented.

In the embodiment shown in FIG. 8 of the drawings, the coacting slide drive means of the gas pipe 30 and the slide block 32 comprises the piston 60 mounted for longitudinal travel within the gas pipe 30, the piston having a rearward extension 61 that extends through the rearward openings 63 formed in the gas pipe 30. The rearward extension 61 of the piston 60 contacts the forward facing surface of the slide block 32 when the slide block is at its forwardmost position as shown in FIG. 8. Similarly, in the embodiment shown in FIG. 9 of the drawings, the coacting slide drive means of the gas pipe 30 and the slide block 32 comprises the piston 64 mounted for longitudinal travel within the gas pipe 30. The slide block 32 has a forward extension 65 that extends through the opening 63 when the slide 13 is at its forwardmost position, the forward extension 65 contacting the piston 64 as shown in FIG. 9. In both embodiments, when a cartridge is fired, powder combustion gases enter the gas pipe 30 through the gas port 25, and these gases drive the pistons 60 and 64 rearwardly, and consequently propel the slide block 32 and the slide 13 rearwardly, in the manner well understood in the art.

The stock 18 is usually made of wood (for example walnut), although metal and molded plastic resins are also commonly employed for this purpose, the stock 18 being secured to the receiver 11 by a bolt or other conventional fastening means. In the preferred embodiment shown in the drawings the stock 18 has a forearm portion 19 that is formed with a channel-shaped longitudinal recess 60 in which the channel-shaped member 42 of the slide guide is received. The forward end portion 19a of the forearm 19 is received in the rearward facing U-shaped recess defined by the channel-shaped member 42 and the U-shaped end cap 48. As noted, the forward end of the channel-shaped member 42 and the end cap 48 are secured to the barrel 10 by means of the locating lugs 53 and the locating ledge 54 of the gas block 21, and as a result the forward end of the forearm 19 is also secured to the barrel 10 by the gas block 21. Thus, it will be seen that the channel-shaped member 42 not only serves to guide the reciprocating slide block 32 but also serves as a liner for the forearm 19 which protects and strongly reinforces the forearm.

When the stock 18 and forearm 19 are made of wood, the channel-shaped member 42 is a separate part that fits fairly freely in the channel-shaped longitudinal recess 60 of the forearm 19. In this case, the forward end of the channel-shaped member 42 is secured to the forward portion 19a of the forearm 19 by means of the U-shaped end cap 48, and the rearward end of the channel-shaped member 42 is secured to the stock 18 by means of the extension retaining lip 57 of the stock liner 31. When the stock 18 and stock forearm 19 are made of metal or of a molded plastic resin, the channel-shaped member 42 is advantageously an integral part of the forearm 19 which is permanently fastened or bonded thereto in the course of manufacture of these parts. In order to protect the reciprocating slide block 32 from dirt and other extraneous debris, and in order to protect the shooter's hand from possible injury or burns, the rifle is advantageously provided with a forearm hand guard 20 that is secured to the rifle in the manner shown best in FIGS. 2 and 4 of the drawings.

The improved slide guide of the invention eliminates the need for the conventional slide guide rod that normally extends through the slide block below the gas pipe longitudinally from the gas block to the receiver, thus greatly reducing the depth and bulk of the forearm 19 in which the reciprocating slide block 32 is contained. In addition, the spring receiving recess 36 of the slide block 32 is advantageously disposed in vertically overlapping relationship with respect to the gas pipe as shown best in FIGS. 2, 6, 8 and 9, thus further reducing the required depth and bulk of the forearm 19.

Claims

We claim:

1. In a gas operated auto-loading rifle having a receiver, a barrel secured to the receiver, a gas pipe mounted on the barrel with the axis thereof generally parallel to the bore of the barrel, the gas pipe being closed at its forward end and having an opening at its rearward end, a gas port for powder combustion gases formed in the side wall of the barrel and communicating with the bore of the barrel and with the gas pipe, a bolt slidably mounted for longitudinal travel in the receiver behind the barrel, a slide having a slide handle connected to the bolt and a slide block disposed adjacent the opening at the rearward end of the gas pipe, said slide being movable longitudinally with respect to the barrel from a forward position at which the bolt is closed to a rearward position at which the bolt is open, a slide spring urging the slide to its forward bolt closed position, co-acting slide drive means associated with the slide and the gas pipe for driving the slide to its rearward bolt open position when powder combustion gases enter the gas pipe, and guide means for guiding the slide block, the improvement which comprises;

slide guide means for guiding the slide block as the slide moves longitudinally with respect to the barrel, said guide means comprising:

an elongated generally channel-shaped member that is disposed beneath the barrel and that extends along the slide from adjacent the gas pipe to adjacent the receiver, said channel-shaped member having a bottom wall, two side walls and an open top, the bottom wall and the upstanding side walls of the channel-shaped members being disposed in close proximity to the bottom and side surfaces of the slide block and the underside of the barrel being disposed in close proximity to the top surface of the slide block whereby said bottom wall and side walls of the channel-shaped member and the underside of the barrel cooperate to guide the slide block and to maintain it in alignment with the gas pipe as the slide moves longitudinally with respect to the barrel,

means for releasably securing the forward end of the channel-shaped member to the barrel in position relative to the gas pipe to insure that the co-acting slide drive means of the slide and the gas pipe are disposed in operational relationship when the slide is moved to its forward position, and

means for releasably securing the rearward end of the channel-shaped member at the receiver.

2. The rifle according to claim 1 in which the slide block is provided with a pair of upper guide ears that extend upwardly on opposite sides of said slide block in close proximity to the corresponding opposite side surfaces of the barrel.

3. The rifle according to claim 1 in which the rifle has a stock and stock forearm, the forearm being formed with a channel-shaped longitudinal recess in which the channel-shaped slide guide member is received, said slide guide member serving as a liner that protects and reinforces said forearm.

4. The rifle according to claim 1 in which the gas pipe has a rearward facing stationary piston portion disposed at the rearward end thereof, said stationary piston portion having a longitudinal hole extending therethrough, and in which the slide block is formed with a forward facing gas chamber in which the rearward facing stationary piston portion of the gas pipe is received when the slide is at its forward position.

5. The rifle according to claim 1 in which a movable piston is mounted for longitudinal travel within the gas pipe, said movable piston being driven rearwardly when powder combustion gases enter the gas pipe, said movable piston having a rearward extension that extends through the rearward opening of the gas pipe, and in which the forward end of the slide block contacts the rearward extension of the movable piston when the slide is at its forward position.

6. The rifle according to claim 1 in which a movable piston is mounted for longitudinal travel within the gas pipe, said movable piston being driven rearwardly when powder combustion gases enter the gas pipe, and in which the forward end of the slide block is provided with a forward extension that extends through the rearward opening of the gas pipe and contacts the movable piston within the gas pipe when the slide is at its forward position.

7. The rifle according to claim 1 in which the slide spring is a compression coil spring the rearward end of which is mounted on the receiver and the forward portion of which is received in a longitudinal spring receiving recess formed in the slide block, the spring receiving recess being disposed in vertically overlapping relationship with respect to the gas pipe, the forward end of said spring receiving recess being located in the slide block a short distance rearwardly from the rearward end of said gas pipe.

8. In a gas operated auto-loading rifle having a receiver, a stock and stock forearm, a barrel secured to the receiver, a gas pipe mounted on the barrel with the axis thereof generally parallel to the bore of the barrel, the gas pipe being closed at its forward end and having an opening at its rearward end, a gas port for powder combustion gases formed in the side wall of the barrel and communicating with the bore of the barrel and with the gas pipe, a bolt slidably mounted for longitudinal travel in the receiver behind the barrel, a slide having a slide handle connected to the bolt and a slide block disposed adjacent the opening at the rearward end of the gas pipe, said slide being movable longitudinally with respect to the barrel from a forward position at which the bolt is closed to a rearward position at which the bolt is open, a slide spring urging the slide to its forward bolt closed position, co-acting slide drive means associated with the slide and the gas pipe for driving the slide to its rearward bolt open position when powder combustion gases enter the gas pipe, and guide means for guiding the slide block as the slide moves longitudinally with respect to the barrel, the improvement in slide guide means which comprises:

an elongated generally channel-shaped member that is disposed beneath the barrel and that extends along the slide from adjacent the gas pipe to adjacent the receiver, means for releasably securing the forward end of the channel-shaped member to the barrel in position relative to the gas pipe to insure that the co-acting slide drive means of the slide and the gas pipe are disposed in operational relationship when the slide is moved to its forward position, and means for releasably securing the rearward end of the channel-shaped member at the receiver, said channel-shaped member having a bottom wall, two side walls and an open top, the bottom wall and upstanding side walls of the channel-shaped member being disposed in close proximity to the bottom and side surfaces of the slide block, said bottom wall and the underside of the barrel cooperating to prevent significant vertical movement of the slide block and said side walls cooperating to prevent significant lateral movement of the slide block while permitting free longitudinal movement thereof,

the stock forearm being formed with a channel-shaped longitudinal recess in which the channel-shaped slide guide member is received, said slide guide member serving as a liner that protects and reinforces said forearm, and a U-shaped end cap being secured to the forward end of the channel-shaped slide guide member, the forward end portion of the channel-shaped member and the U-shaped end cap defining a rearward facing U-shaped recess in which the forward end of the forearm is received.

9. In a gas operated auto-loading rifle having a receiver, a barrel secured to the receiver, a gas pipe mounted on the barrel with the axis thereof generally parallel to the bore of the barrel, the gas pipe being closed at its forward end and having an opening at its rearward end, a gas port for powder combustion gases formed in the side wall of the barrel and communicating with the bore of the barrel and with the gas pipe, a bolt slidably mounted for longitudinal travel in the receiver behind the barrel, a slide having a slide handle connected to the bolt and a slide block disposed adjacent the opening at the rearward end of the gas pipe, said slide being movable longitudinally with respect to the barrel from a forward position at which the bolt is closed to a rearward position at which the bolt is open, a slide spring urging the slide to its forward bolt closed position, co-acting slide drive means associated with the slide and the gas pipe for driving the slide to its rearward bolt open position when powder combustion gases enter the gas pipe, and guide means for guiding the slide block as the slide moves longitudinally with respect to the barrel, the improvement in slide guide means which comprises;

an elongated generally channel-shaped member that is disposed beneath the barrel and that extends along the slide from adjacent the gas pipe to adjacent the receiver, means for releasably securing the forward end of the channel-shaped member to the barrel in position relative to the gas pipe to insure that the co-acting slide drive means of the slide and the gas pipe are disposed in operational relationship when the slide is moved to its forward position, and means for releasably securing the rearward end of the channel-shaped member at the receiver, said channel-shaped member having a bottom wall, two side walls and an open top, the bottom wall and upstanding side walls of the channel-shaped member being disposed in close proximity to the bottom and side surfaces of the slide block, said bottom wall and the underside of the barrel cooperating to prevent significant vertical movement of the slide block and said side walls cooperating to prevent significant lateral movement of the slide block while permitting free longitudinal movement thereof, the inner surfaces of the bottom and side walls of the channel-shaped member being formed with longitudinally extending guide ribs disposed in close proximity to the corresponding bottom and side surfaces of the slide block.

10. The rifle according to claim 9 in which the gas pipe is mounted on a gas block which is mounted on the barrel, and in which the gas block is provided with rearwardly extending slide guide locating lugs, said locating lugs engaging the forward end of the channel-shaped slide guide member and positioning said forward end relative to said gas pipe.

11. The rifle according to claim 10 in which a U-shaped end cap is secured to the forward end of the channel-shaped slide guide member and in which the lower periphery of the gas block is formed with a rearwardly extending U-shaped slide guide locating ledge disposed radially outwardly with respect to said slide guide locating lugs, said locating ledge engaging the outer peripheral surface of the U-shaped end cap and said locating lugs engaging the inner peripheral surface of the said channel-shaped slide guide member.

12. The rifle according to claim 11 in which the rifle has a stock and stock forearm, the forearm being formed with a channel-shaped longitudinal recess in which the channel-shaped slide guide member is received, and in which the forward end portion of the channel-shaped member and the U-shaped end cap define a rearward facing U-shaped recess in which the forward end of the forearm is received.