Bullpup stock kit for a rifle

The present invention provides for a stock kit that converts a conventional rifle, such as an SKS, into bullpup configuration. The preferred embodiment of the provided stock kit does not require any permanent modification be made to the host firearm. The stock kit also provides for a rotatable handguard, trigger safety and a magazine release.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to firearms. More particularly, the present invention relates to stock kits which convert a traditional rifle into bullpup configuration.

2. Description of the Prior Art

Traditionally rifles using detachable magazines are configured so that the action of the firearm and the ammunition magazine are located in front of the trigger. Rifles configured so that the action and the magazine are located behind the trigger of the firearm are referred to as “Bullpups”.

Rifles in a bullpup configuration offer several advantages over the more traditional rifle configuration. One of these advantages relates to barrel length. A bullpup having the same overall length as a traditionally configured rifle will have a longer barrel. This is due to the positioning of the action closer to the rear end of the buttstock. Longer barrels are typically associated with increased accuracy and better external and terminal ballistic performance.

While the action and the mounting position of the ammunition magazine are moved towards the rear end relative to the buttstock, the position of the trigger stays relatively the same. This requires a new mechanism to place the trigger and the sear of the firearm's action into operational communication.

In certain instances, end users of more traditional rifles may desire to alter the appearance and functionally of their more traditionally configured rifle into that of a bullpup. This may be done to improve ergonomics, reduce weight, and reduce overall length without compromising ballistic performance. Such a modification would be particularly desirable if it required minimal expertise and mechanical skill.

In addition to a new rifle stock kit for the host firearm, a mechanism to reposition the trigger forward of the action and the magazine must be provided for in order to complete the bullpup conversion.

Therefore in consideration of what is available in the prior art, there exist a need for a rifle stock kit which converts a traditionally configured rifle into bullpup configuration. Such a stock kit should require minimal gunsmithing knowledge or mechanical expertise to install and provide a mechanism to reposition the trigger forward of the action and the magazine.

SUMMARY OF THE INVENTION

In view of the foregoing, one object of the present invention is to meet the recognized need for such an apparatus that converts a traditionally configured rifle into bullpup configuration by providing a rifle stock kit which includes a mechanism for repositioning the trigger.

Another object of the present invention is to provide a rifle stock kit in accordance with the preceding objects which provides for a rotatable handguard that may be used as vertical foregrip.

Yet another object of the present invention is to provide a rifle stock kit in accordance with the preceding objects which provides a mechanism to facilitate removal of the ammunition magazine.

A further object of the present invention is to provide a rifle stock kit in accordance with the preceding objects which provides a trigger safety mechanism.

In accordance with these and other objects, the present invention is directed to a rifle stock kit which is configured to receive the barreled action of a firearm and convert it to a bullpup configuration. The rifle stock kit consists of a three piece chassis system, a mechanical device to connect the trigger provided by the stock kit to the sear of the barreled action, a mechanical trigger safety, a rotatable handguard and a magazine release. The preferred embodiment of the rifle stock kit is configured to work with a SKS type rifle.

The chassis system provided for herein consists of a body portion, top portion and a buttstock portion. The body portion is configured to receive the barreled action of an SKS type rifle. The body portion provides for a pistol grip and trigger that are located in front of the firearm's action and the firearm's magazine. Provided on the pistol grip is a mechanical safety which must be disengaged in order to operate the trigger. The trigger is provided with a mechanical link which extends therefrom back to the action of the SKS, placing the two into operational communication.

Located on the bottom portion of the chassis in front of the trigger is a handguard which is grasped by a users support hand during operation of the firearm. The handguard is rotatable and may be used as a foregrip, sometime referred to as a vertical foregrip.

Located adjacent to the magazine catch present on the action of the SKS is a magazine release lever. The magazine release lever is secured to the bottom portion of the chassis and provides two contact surfaces. By operating either contact surface the magazine may be quickly released.

These together with other improvements and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In describing a preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

The present invention is directed towards a rifle stock kit that may be used to convert a traditionally configured rifle into bullpup configuration. The rifle stock kit also provides for an integrated rotatable handguard that may be used as a vertical foregrip, a trigger safety and a magazine release. As used herein, the phrases rifle stock kit and bullpup stock kit are used interchangeably.

It is to be understood that the term “action” as used throughout this specification includes the bolt, receiver and trigger mechanism of the firearm used with the preferred embodiment of the present invention. The firearm used with the preferred embodiment is a Samozaryadnyj Karabin sistemy Simonova rifle, commonly referred to as an SKS. The SKS is typically chambered to fire 7.62×39 mm ammunition.

Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, as used herein, the word “front” or “forward” corresponds to where the muzzle end of the barrel is located (i.e., to the right as shown inFIGS. 1,3and15-17); “rear” or “rearward” or “back” corresponds to the direction opposite where the muzzle end of the barrel is located (i.e., to the left as shown inFIGS. 1,3and15-17).

As shown inFIGS. 1-2and15, the present invention is directed to a bullpup stock kit, generally designated by reference numeral20, for use with the barreled action11of an SKS type rifle. The combination of the barreled action11and the bullpup stock kit20is referred to as the bullpup configured rifle, or simply bullpup, and is designated by reference number10.

Best shown in the exploded view ofFIG. 3, the bullpup stock kit20generally consists of a top portion26, a body portion24, a buttstock portion28, a trigger30, trigger safety32, a trigger link34and a magazine release lever60. The combination of the body portion24, top portion26and buttstock portion28are collectively referred to herein as the chassis22. Also shown inFIG. 3is a detailed view of an SKS rifles barreled action11. The barreled action11is comprised of an action18(receiver and bolt), barrel14, handguard cap17and gas tube16. The action18also has a trigger13, a sear15, a hammer19, and a magazine release5. The magazine release5is sometimes referred to herein as a magazine catch.

A perspective side view of the chassis's22body portion24is shown inFIG. 4. The chassis22is configured to receive the barreled action11in a channel23which extends between the back of the body portion24to its front. The channel23defines an interior bottom portion40with two side walls41A and41B extending therefrom. Side walls41A and41B generally occupy parallel plans.

Extending from the bottom side of the body portion24is a pistol grip25and a trigger guard27. The pistol grip25and trigger guard27are connected together. Located on the front end of the body portion24is a joint29to which the handguard21is mounted as shown inFIGS. 1-3and15-17. Located on the underside of the body portion24near the back end is an opening61configured to receive the magazine release60lever therein (seeFIGS. 1-3). Located adjacent to and connected with the opening61for the magazine release lever60is an opening64configured to receive a portion of the ammunition magazine12therein (seeFIG. 5). The opening64is often referred to as a magazine well. Located adjacent the rear most end of the body portion24is a thru-bore42. The function of which will be described in greater detail in the following paragraphs.

Located on each side wall41A and41B, above the trigger guard27, are two thru-bores43. The thru-bores43located on side wall41A are in alignment with the thru-bores43present on side wall41B. Located between the thru-bores43within the interior of the body portion24is a pocket44(seeFIGS. 4-7). The pocket44is configured to receive the handguard cap adaptor70described below (seeFIGS. 6-9).

The handguard cap adaptor70has a protruding lip71on its front end constructed to be received by a portion of the handguard cap17(seeFIGS. 16-17). It has an interior channel72configured to receive a portion of the barrel14therein when the barreled action11is secured within the body portion24of the chassis22. Four openings73through the top portion of the handguard cap adaptors'70body are provided (seeFIGS. 7-9). There are two openings73on each side of the handguard cap adaptor70, each opening73being in alignment with an opening73located on the opposite side of the handguard cap adaptor70. When the handguard cap adaptor70is placed within the pocket44, the openings73are aligned with the thru-bores42of the body portion24of the chassis22(seeFIG. 7). Once the openings73are in alignment with the thru-bores42, two roll pins45(seeFIGS. 2-3) are used to secure the handguard cap adaptor70to the body portion24of the chassis22. Alternatively, a screw or friction pin may be used without departing from the scope of the present invention.

When the barreled action11is secured within the channel of the body portion24, a portion of the handguard cap18receives therein the protruding lip71of the handguard cap adaptor70(seeFIGS. 16-17).

The pocket44is constructed to receive handguard cap adaptors70of varying size (seeFIGS. 4-7). This is useful because the exact location of the handguard cap17on the gas tube16as it relates to the action18of the firearm varies based on the SKS rifles nation of origin. The overall length of the handguard cap adaptor70or the protruding lip71may be varied to accommodate the dimensional variations which exist between SKS type rifles manufactured at different arsenals.

FIG. 10shows a side perspective view of the chassis22top portion26. The top portion26has an ejection port opening80which allows the user to operate the action18of the bullpup10and facilitates the ejection of spent ammunition cases during firing (seeFIGS. 1,3,10and15). Located on its forward most end is a protruding lip81. The protruding lip81has a generally “U” shape, similar to the protruding lip71of the handguard cap adaptor70.

The top portion26defines an interior opening82configured to fit around a portion of the barreled action11. Two side walls83A and83B are provided on the back end of the top portion26. Each side wall83A and83B defines an opening84therethrough which is in alignment with an opening84in the other side wall83A and83B.

The top side of the chassis's22top portion26includes an elevated mounting platform85(FIG. 10). Secured to the elevated mounting platform85is a rail segment89(seeFIGS. 1-3and15-17). The rail segment80includes a number of rails extending therealong separated by traverse grooves88therebetween (seeFIGS. 3 and 15). In the illustrated embodiment, the rail segment89of the elevated mounting platform85is manufactured in accordance with the MIL-STD-1913 rail specifications. The rail segment89facilitates the attachment of iron sights and/or optical gun sights based on user preference. Other attachment surfaces which facilitate the attachment of optics and iron sights could be used in place of the rail segment89shown and described herein. In the preferred embodiment, the rail segment89is secured to the elevated mounting platform85through the use of screws.

FIGS. 11 and 12show detailed illustrations of the chassis's22buttstock portion28. The back side90defines thereon a textured surface which prevents the bullpup10from slipping off of the users shoulder during firing. Extending from the back side90of the buttstock portion28are two arms91A and91B. Each of the arms91A and92B are configured to interface with the body portion24and top portion26of the chassis22. Near the proximal end of each arm91A and91B is an opening92A and92B, respectively. Also provided on the buttstock portion28is a thru-bore94, the purpose of which will be later described in detail.

The arms91A and92B are constructed to be received within an interior opening which is present after the body portion24and the top portion26of the chassis22are attached to the barreled action11during assembly.

FIGS. 13 and 14show exploded views of the body portion's rotatable handguard21. The joint29has an opening95therethrough configured to receive a pin93(FIGS.4and13-14). The opening95has an eight side star-shaped opening on one end which has tapered interior side walls and a generally circular opening on the other end. The pin93has a head96portion, a threaded portion102and a cylindrical body portion extending therebetween. The preferred embodiment pin93is a shoulder bolt. Also provided are a coil type spring97, a star-shaped locking piece110having a threaded interior opening and tapered exterior side walls and an end button98having a centrally located opening therethrough.

The rotatable handguard21is configured to be grasped by the user during use of the bullpup10. The preferred embodiment handguard21is also constructed so that it may be rotated and used as a vertical foregrip. Located on its forward end is an opening99which extends through sides walls105A and105B. The portion of opening99on side wall105B has the general shape of an eight point star, the interior side walls of which are tapered. The portion of opening99on side wall105A is generally circular (seeFIGS. 13 and 14). The handguard21defines an interior100area configured to be received against the body portion24when in the closed position (seeFIGS. 1-4).

To attach the handguard21to the body portion24, the gap101of the handguard21located generally between side walls105A and105B is placed about the joint29of the body portion24. When the joint29is within the gap101, opening95and opening99are in alignment with each other. The spring97and end button98are then placed within the circular portion of opening99. The star-shaped locking piece110is inserted into the star-shaped portions of opening99and95, respectively. The pin93is then inserted through the aligned openings95and99and threadedly secured to the star-shaped locking piece110(seeFIGS. 13 and 14). The end button98holds the spring97in place when the pin93is threadedly secured to the star-shaped locking piece110.

The star-shaped locking piece110secures the handguard21against unintentional movement when it is seated within opening95and99. The foregrip21may be disassembled by reversing the above outlined steps.

By varying the shape of the locking piece110and the appropriate portions of openings95and99, the number of positions into which the handguard21may be moved can be varied. The preferred embodiment of the handguard is provided with at least three positions of use.

The foregrip21may be placed in a closed position, also referred to as a first position, as shown inFIGS. 1-4. In its closed position, the rotatable handguard21acts as a conventional handguard. Alternatively, the handguard21may be rotated to a second or third position where is acts as a foregrip. The second position places the length of the handguard at an approximate 45 degree angle as it relates to the longitudinal axis of the body portion24of the chassis22. The third position places the handguard21into a vertical position where it is at an approximately 90 degree angle in relationship to the chassis's22body portion24(seeFIGS. 15-17).

The rotatable handguard21is moved between positions by pressing side wall105A towards the body portion24. This action compresses spring97and causes the star-shaped locking piece110of pin93to be pushed out of engagement with the star-shaped portion of opening95. The handguard21is the free to rotate to the next provided position at which time the pressure being placed on side wall105A is released. Once pressure is release from side wall105A the star-shaped locking piece110is received within another portion of the star-shaped portion of opening95. Once the star-shaped locking piece110has been received within the star-shaped portion of opening95the handguard is secured against unintentional movement.

The trigger30and trigger safety32provided by the bullpup stock kit20are mounted to the body portion24of the chassis24(seeFIGS. 1-3). The trigger30has two thru-bores31A and31B there through and defines a contact surface46thereon (seeFIGS. 13-14). The trigger safety32has one thru-bore39there through and defines a contact surface47thereon (seeFIGS. 13-14). The contact surfaces46and47of the trigger30and trigger safety32, respectively, are preferably textured.

The body portion24of the chassis22provides two openings35and36therethrough for mounting the trigger30and trigger safety35, respectively (seeFIGS. 1-5and13-14). Opening36also passes through the structure37, or mounting position, provided within the interior channel23of the body portion24. The provided structure37is constructed to receive the trigger30therein and minimize its side to side movement during operation (seeFIGS. 5 and 7).

The pistol grip25portion of the chassis22has a hollow38therein configured to receive the trigger safety32, trigger safety spring33, and a portion of the trigger30(seeFIGS. 4-5and16-17). The trigger safety32has a fist position of operation shown inFIG. 16and a second position of operation shown inFIG. 17.

The spring33biases the trigger safety32into the first position. The first position of the trigger safety32has the safety sear48engaged with a rearwardly protruding member49of the trigger30. This engagement between the safety sear48and protruding member49prevents the rearward movement of the trigger30(seeFIG. 16).

When the contact surface47of the trigger safety32is depressed towards the back side of the pistol grip25, the safety sear48is rotated out of engagement with the protruding member49of the trigger30. This is called the second position of the trigger safety32(seeFIG. 17). In this position, if the trigger30contact surface47is acted on by the user, the trigger30will move towards the rear allowing the bullpup10to be fired.

Another portion of the bullpup stock kit20is the magazine release lever60(seeFIGS. 1-3and15-17). The magazine release lever60has a thru-bore50located near its approximate center. Located on its forward face, near its top, is a textured contact surface63. Located adjacent its bottom surface is another contact surface65. Located opposite the contact surface63on the forward face of the magazine release lever60is the engagement surface66(seeFIGS. 16-17).

When the magazine release lever60is attached to the body portion24of the chassis22, the engagement surface66is in contact with the magazine release5of the action18. When the contact surface63of the magazine release lever is depressed, the engagement surface66pushes the magazine release5of the action18towards the rear of the rifle10allowing the magazine12to be removed.

Alternatively, the user may push the contact surface65provided on the bottom of the magazine release lever60forward. This motion causes the engagement surface66of the magazine release lever60to push the magazine release5of the action18towards the rear. The magazine12may be removed from the bullpup12once the magazine release5has been moved sufficiently towards the rear.

The magazine12is secured within the magazine well of the chassis22, to the barreled action11in a manner well known throughout the prior art as it concerns SKS type firearms. In alternate embodiments of the bullpup stock kit20, the method of securing a magazine into place will vary according to the barreled action used.

The magazine release lever60is secured to the body portion24of the chassis22as follows. The magazine release lever60is inserted into the opening61provided in the body portion24. The thru-bore50of the magazine release lever60is aligned with the opening62provided on the body portion24of the chassis22. When the thru-bore50is aligned with the opening62, a friction pin is inserted through the aligned openings thereby securing the magazine release lever60in place. The friction pin provides a surface about which the magazine release lever60rotates.

FIG. 18shows a view of the barreled action11used with the preferred embodiment of the herein described invention. Also shown is the trigger30, trigger link34and the sear engagement member52.

When a barreled action11has been mounted in the chassis22of the present invention, a trigger link34extends between the trigger30provided for herein and the trigger13of the host firearms action18(seeFIG. 18). At its forward end, the trigger link34has a bend51which is received within a thru-bore31A of the trigger30(seeFIGS. 13-14and18). The trigger link34extends rearwardly from the trigger30towards the host firearms action18. The rearward end of the trigger link34is received within a thru-bore54located at one end of a sear engagement member52, or engagement member. When assembled therewith, the engagement member52extends perpendicular to the longitudinal axis of trigger link's34rearward end. The engagement member52has a generally cylindrical shape, the exterior surface of which has a plurality of flat surfaces53thereon (seeFIG. 18).

The engagement member52is secured to the trigger link34through the use of a set screw (not shown). A bore (not shown) is off set from the thru-bore54and threaded. This threaded bore receives a set screw which when tighten into place comes into direct contact with the trigger link34. While the set screw is in contact with the trigger link34the engagement member52is unable to move. This method of assembly allows for the precise placement of the engagement member52during installation.

The bullpup stock kit20is installed on a barreled action as follows. Initially the handguard cap adaptor70and the magazine release lever60are installed on the body portion24of the chassis22as described above. Then the spring33and trigger safety32are inserted within the hollow38of the pistol grip25(seeFIGS. 16-17). The thru-bore39of the trigger safety32is aligned with opening36of the body portion24. A friction pin is used to secure the trigger safety32and spring33into place within the hollow38of the body portion24.

The bend51of the trigger link34is now inserted into thru-bore31A of the trigger30. The trigger30is then inserted into the opening formed between the two walls which define its mounting position37within the body portion24of the chassis (seeFIG. 5). The trigger30is secured in place through the use of a roll pin which is inserted through opening35of the body portion and opening31B of the trigger30(seeFIGS. 1-2and15).

Next, the barreled action11is positioned above the body portion24of the chassis22. Then the sear engagement member52is installed on the trigger link34as described above (seeFIG. 18). The engagement member60is positioned on the trigger link34so that a portion of its exterior53is positioned behind the sear15of the action18when inserted therein. While the engagement member60is so positioned, the length of the trigger link34runs parallel to the longitudinal axis of the barreled action11.

The barreled action11is then inserted into the channel23of the body portion22so that the protruding lip71of the handguard cap adaptor70is received within the lower portion of the handguard cap17(seeFIGS. 16-17). Next, the top portion of the chassis22is placed over the top of the barreled action11. The top portion26is positioned so that the protruding lip81on its front end is received within a portion of the handguard cap17(seeFIGS. 1-2and15-17). The action18is received within the interior opening82of the top portion26. The arms91A and91B of the buttstock portion28are inserted into the opening formed between the top portion26and the body portion24. When properly installed, openings92A and92B of the buttstock portion28are in alignment with opening84of the top portion26. A pin is inserted through these aligned openings to secure the buttstock portion28to the top portion26. Concurrently, the thru-bore94of the buttstock portion28is also in alignment with the thru-bore42of the body portion24. A screw or friction pin is then inserted into the aligned thru-bores42and94, effectively securing the buttstock portion28to the body portion24.

To remove the bullpup stock kit20described above, simply reverse the above outlined steps.

When the trigger30is pulled to the rear the trigger link34is pulled forward. The forward movement of the trigger link34causes the engagement member54is push against the back side of the sear15of the action18. Once sufficient pressure has been applied to the sear15, the hammer19is released allowing the bullpup10to fire in a manner well know throughout the prior art.

Use of the magazine releaser lever60has been described in detail above.

The magazine release lever60, trigger30, trigger safety32, handguard21and the body portion24, buttstock portion28and top portion26of the chassis22are manufactured from nylon sixty six. While nylon sixty six is the preferred material, any material suitable for use with firearms may be substituted. All of these components are preferably manufactured through an injection molding process.

The exact shape and textures of the chassis's22exterior surfaces may be varied without departing from the scope of the invention disclosed herein.

In an alternate embodiment, the rotatable handguard21could be omitted entirely without departing from the scope of the present invention. In lieu of the rotatable handguard21, a non-moving handguard or a fixed position vertical foregrip could replace it.

In still another alternate embodiment, iron sights could be provided as part of the top portion26of the chassis22without departing from the scope of the present invention.

The foregoing descriptions and drawings should be considered as illustrative only of the general principles of the invention. This invention is not limited for use with the barreled actions of SKS types rifles; rather it may be used with any rifles barreled action which has a similar sear15mechanism. Numerous applications of the present invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.