Patent ID: 12241717

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 compact buffer assembly for use with AR15/M16 type firearms to include, for example, the M4, AR10, SR25 and piston operated designs such as LWRC International's M6 series of rifles. As used herein, the phrase “bolt carrier group” and “bolt carrier assembly” are used interchangeably.

Unless otherwise specified, the various components which make up the trigger mechanism, upper receiver assembly, lower receiver assembly, bolt and bolt carrier assembly are those found on prior art AR15/M16 type firearms.

As used herein, the word “front” or “forward” corresponds to the end of the bolt carrier20where the bolt11is located (i.e., to the left as shown inFIGS.1B-3, &5); “rear” or “rearward” or “back” corresponds to the direction opposite the end of the bolt carrier20where the bolt11is located (i.e., to the right as shown inFIGS.1B-3, &5). The phrase “in battery” or “battery” refers to the position of readiness of a firearm for firing.

As shown inFIG.1B, the present invention is directed to a compact buffer assembly, generally designated by reference numeral10, including a generally cylindrical bolt carrier20with an attached buffer40, a bolt11, a buffer spring12and a buffer tube50(e.g., approximately 3.9″ long) having an interior configured to receive a portion of the bolt carrier20therein. It will be understood that the buffer assembly10is intended to be employed with any of the various AR15/M16 type firearms; however with minor modifications, some of its features could be more widely used for other firearms as well. It will also be understood that the bolt carrier20with attached buffer40is housed within an upper receiver81of an AR15/M16 type rifle80(seeFIGS.6A-6G and7).

InFIGS.1B-4, an embodiment of the bolt carrier20is shown. The bolt carrier20is generally cylindrical in shape and includes a bore30which extends between its front end31and back end32, varying in dimension based on a specific region's function and the structure defined thereon. The bolt carrier20also includes a hammer clearance slot26which permits the hammer to extend into the bolt carrier20and strike a firing pin13positioned in a portion of the bore30. The firing pin13is retained in place through the use of a cotter pin15, also commonly referred to as a firing pin retaining pin.

The exterior of the bolt carrier20includes an ejection port cover opener28which provides room for the ejection port cover to close and a cam slot27which provides a contained area for the cam pin14to rotate and thereby facilitate limited rotational and longitudinal movement of an attached bolt11(seeFIGS.1B,2,3and4).

Located on the top surface of the bolt carrier20is an integral carrier key29. The general features and advantages of the integral carrier key29are described in U.S. Pat. No. 8,387,513, filed on May 14, 2010, entitled “Self Loading Firearm Bolt Carrier With Integral Carrier Key And Angled Strike Face”, by Jesus S. Gomez, Jason Miller, Robert S. Schilling, and Michael R. Llewellyn (hereinafter, “the Gomez et al application”), which is also owned by the assignee of the present application and is hereby expressly incorporated by reference as if fully set forth herein.

As shown in the exploded view of the bolt carrier20and buffer40provided inFIG.2, and the isolated views of the same shown inFIGS.3-4, the buffer40is attached to the back end of the bolt carrier20. The bolt carrier20has a bore21through the interior of its back end which receives a portion of the buffer40. The buffer40consist of two parts, a bumper41with integral shaft42and a cylindrical weight43attached thereto. The method of attaching the weight43to the shaft42of the bumper41will be described more fully hereinafter.

Horizontal side views of the bolt carrier20with attached buffer40are provided inFIGS.3and4. The rear of the bolt carrier20has a boss22for contacting an interior portion86of the upper receiver81(seeFIG.7), thereby providing support during its longitudinal movement therein. The boss22is generally cylindrical in shape having an outside diameter larger than the body portion of the bolt carrier20. The boss is also of sufficient diameter to make contact with the cylindrical interior of the buffer tube50(FIGS.1B and7) to ensure that the bolt carrier20remains centered therein. The boss22defines a circular side wall33(FIGS. 3-5) on its backside which occupies a plane perpendicular to the longitudinal axis of the bolt carrier. The general features and advantages of the boss22are described in a U.S. Pat. No. 8,375,616 filed on Dec. 10, 2008, entitled “Automatic Rifle Bolt Carrier with Fluted Boss”, by Jesus S. Gomez and Jason Miller (hereinafter, “the Gomez and Miller application”), which is also owned by the assignee of the present application and is hereby expressly incorporated by reference as if fully set forth herein. Also present on the rearward end of the bolt carrier is a guide rod portion23(FIGS.2-5) which is configured to engage with and support the buffer spring12(shown inFIG.1B) as will also be described more fully hereinafter.

FIG.5shows a cutaway view of an embodiment bolt carrier20with attached bolt11, firing pin13, and cam pin14. The bolt carrier20has an interior thru bore21extending between its rear end and the hammer clearance slot26(FIGS.2-4) of sufficient diameter to facilitate the passage of the buffer's40shaft42portion. Further, the interior diameter of the thru bore21is smaller than the exterior diameter of either the bumper41or cylindrical weight43portions of the buffer40. There is a countersunk bore24about the front end of the thru bore21configured to receive a portion of the cylindrical weight43and resist its rearward movement. Located on the back end32of the bolt carrier20is an annular side wall25which a portion of the bumper41contacts during the buffer's40rearward movements.

Views of a AR15/M16 type personal defense weapon (PDW), generally designated by reference numeral80, used with one embodiment of the buffer assembly10and buttstock assembly90are shown inFIGS.6A-6C,6E-6G, and7.FIG.6A-6Gshow various views of the personal defense weapon80, also referred to herein as a firearm, and the major components from which it is comprised. Specifically, the upper receiver assembly81, lower receiver assembly83, handguard82, flash hider84and buttstock assembly90are shown.FIG.7shows a cutaway of the view illustrated inFIG.6B. This view shows the linear relationship between the barrel85, bolt carrier20with attached buffer40, buffer spring12(seeFIGS.1B and7), and the buffer tube50. When the bolt carrier20is in battery a majority of the bolt carrier20and buffer40are present within the interior portion86of the upper receiver81. A small portion of the buffer40extends into the buffer tube50(seeFIG.7). The PDW illustrated is equipped with an 8″ barrel85, giving the firearm an overall length of approximately 20″.

Shown inFIG.8is the buffer40which generally consists of a cylindrically shaped weight43having an interior opening44there through and a bumper41portion having an integral shaft42. The distil end45of the shaft42is smaller in diameter than the rest of the shaft42and is constructed to be received within the interior opening44of the cylindrical weight43. The components which make up the buffer40are manufactured from tungsten steel, but other, metals, iron and steel alloys of sufficient weight/density would suffice. All components of the buffer40are weighted to reduce the occurrence of bolt bounce, to provide for proper dwell time and, in general, to facilitate the proper operation of the host firearm. The bumper41portion could have a softer material attached thereto to further buffer the firearms recoil cycle without departing from the scope of the claimed invention.

The buffer spring12shown inFIGS.1B and7is a compression type spring having coils with a rectangular cross section. Alternatively, a traditional compression type spring with round coils could be substituted. In one embodiment, buffer spring12is manufactured from stainless steel but any material, such as chrome-silica, appropriate for use as a compression spring, is suitable.

As noted earlier, the bolt carrier20is received within a buffer tube50, sometimes referred to as a receiver extension, which is shown inFIGS.1B,7,9and11. The buffer tube50has an opening51on its front end which leads to a circular interior bore52sized to contain a portion of the buffer spring12and receive a portion of the bolt carrier20when it is rearwardly displaced during operation of the host firearm80. The forward exterior of the buffer tube50body54is threaded53and constructed to be threadedly received within an interior opening present on the lower receiver83. The back end55(FIG.9) of the buffer tube50is closed on in the embodiment shown, alternate embodiments may have a small liquid drain hole (not shown). Located between the threads53on the front of the buffer tube50and the back end55of the buffer tube are two circumferential ridges56A and56B (FIG.9). The circumferential ridges have a larger outer diameter than the body54of the buffer tube50and are used to support the housing91portion of buttstock assembly90as shown inFIG.11.

The buttstock assembly90as shown inFIGS.6A-6C,6E-6G,7and10-11is comprised of three main components, a housing91, shoulder stock93and two guide rods92A and92B (seeFIGS.10and13). The exterior surface of the housing91is contoured and shaped to act as a cheek piece97or comb. The interior of the housing91defines a longitudinally extending circular bore99sized to receive the buffer tube50(FIG.10). The interior bore99is specifically sized such that the circumferential ridges56A and56B of the buffer tube make contact with the interior bore of the housing91(seeFIG.11). On the housing's91forward face98is a protrusion94(FIG.10) which engages with an opening present on AR15/M16 type lower receivers83to prevent the unintentional rotation of the buttstock assembly90when assembled therewith. The housing91also defines thereon three openings, an opening95which allows the threaded portion53of the buffer tube50to pass through and two smaller openings96A and96B, which receive and support a portion of each guide rod92A and92B respectively. The opening95is smaller in diameter than the interior bore99thereby creating an internal shoulder100between the two.

Located along the bottom side of the housing91is a placement114with an opening116that houses a spring118biased catch115used to operate the buttstock assembly90(FIG.12). The opening116runs traverse to the longitudinal axis of the housing's91interior bore99and is in communication with an opening119configured to receive a roll pin113(FIG.12). The catch115consists of two openings124with a cylindrical body123portion extending therebetween (FIG.12). The cylindrical body123portion has a pressure pad132on the end opposite its distal end134. The pressure pad132is the portion of the catch115to which the user applies force in order to operate the mechanism. One side of each opening124defines a detent117portion which is configured to engage with the notches120and121found on each guide rod,92A and92B (seeFIGS.12and13). The cylindrical body123of the catch115has a slot125therein constructed to receive a portion of the roll pin113. Located at one end of the catch115is a bore133configured to receive a roll pin131(FIG.12). Also provided is a spring118, and a head piece127. The head piece127has a generally cylindrical shape with a centrally placed, longitudinally extending aperture128through its center (FIG.12). There is also a gap129through a side body portion of the head piece127. Located at one end is a bore130configured to receive a roll pin131.

To assemble the catch mechanism, the body portion123of the catch115is inserted through the central opening of the spring118. The distil end134of the catch115is then inserted into the aperture128of the head piece127, effectively capturing the spring118therebetween. Next, the bore130of the head piece127is aligned with the bore133of the body portion123then a roll pin131is pushed through both bores130and133, thereby securing the two pieces together. The catch115, with attached spring118, is then inserted into the opening116of the housing91. The catch115is oriented so that the bottom of each opening124is facing up (seeFIG.12), thereby placing the slot125in alignment with opening119. A roll pin113is inserted through opening119into slot125in order to secure the catch115to the housing91.

When the catch115is secured within the opening116provided on the housing91, the spring118is captured between the roll pin113and a lip135formed between the body123and detent portion117of the catch115. The spring118biases against the roll pin113when the pressure pad132of the catch115is actuated. In one embodiment, the housing91is constructed from aluminum. Alternatively, polymers or other suitable metals or metal alloys may be used.

The shoulder stock93defines a front side105and a back side106with a bore107extended therebetween (FIG.10). The bore107defines a circular opening configured to receive the portion of the buffer tube50located between the back side55and the back face of circumferential ridge56B (FIG.11). There is a circumferential chamfer108located about the front side of the bore107. Also found on the front side105are two openings110A and110B each configured to receive the back end of a guide rod92A and92B, respectively (FIG.10). In one embodiment, shoulder stock93is manufactured from aluminum, but alternate embodiment configurations may be manufactured from polymers or other suitable metals without departing from the scope of this invention.

The back side106, or butt, of the shoulder stock93is textured so as to provide a nonslip surface. Two side walls113A and113B are defined by the shoulder stock93(FIG.10). There is a rectangular shaped opening126through each of the side walls113A and113B which provide mounting points for a rifle sling (FIG.10).

The guide rods92A and92B are elongated, generally circular shaped rods each having two approximately semi-circular notches120and121along one side (seeFIGS.11and13). Also present is a bore122(seeFIG.13) that runs transverse to the longitudinal axis of each guide rod92A and92B. This bore122is located near each guide rod's back end and is configured to receive a roll pin109(seeFIGS.11and13).

A portion of each guide rods92A and92B rearward end is received within a bore110A and110B found in the front side105of the shoulder stock93(FIG.10). The shoulder stock93has two openings112, one opening112in communication with each bore110A and110B (FIG.10). The guide rods92A and92B are inserted into their respective bores110A and110E and are rotated until the bore122found on each guide rod92A and92B is aligned with the appropriate opening112of the shoulder stock93(FIGS.10and13). A roll pin109is inserted through the aligned bore122and opening112of each guide rod92A and92B thereby securing them in place (FIGS.10and11). In one embodiment, guide rods are manufactured from aluminum, but alternate embodiments could be manufactured from other light-weight and durable metal alloys.

The shoulder stock93, with attached guide rods92A and92B, is slidably secured to the housing91as follows. Guide rod92A and92B are inserted within the longitudinally extending openings96A and96B of the housing respectively (FIG.10). The guide rods92A and92B will slide freely forward until the forward notch120of each guide rods is engage by the detent117portion of the spring118biased catch115, preventing further movement. This is referred to as the “first position” (seeFIG.10) of the shoulder stock93and is typically used when firing the attached firearm. To further collapse the shoulder stock93and move between the first and second positions, the catch115is depressed thereby disengaging the detents117from the forward notch120of each guide rod92A and92B. With the detents117disengaged, the shoulder stock93and guide rods92A and92B may be pushed forward until the detents117of the catch115engages with the rearward notch121. This is referred to as the “second position” of the shoulder piece (seeFIG.6B). When the detents117engage with the rearward notches121of the guide rods, the bore107of the shoulder stock93also receives a portion of the buffer tube50therein. The second position of the shoulder stock93is typically selected when the host firearm is to be transported or stored. But, it is important to note that the second position of the shoulder stock93in no way inhibits the firearm from being used. To move the shoulder stock93back to the first position, simply pull on the shoulder stock and the detents117will slip out of the rear notch121of each guide rod92A and92B, allowing the shoulder stock93to extend until the detents115reengage with the forward notch120on each guide rod.

The gap between the guide rods92A and92B, and by extension the openings96A and96B which receive them, has to be large enough for the guide rods to clear the back end portion of the lower receiver83as shown inFIGS.6A-6C,6F and6G.

To attach the buffer40to the bolt carrier20, the shaft portion42of the bumper41is pushed through the enclosed thru bore21located on the back end32of the bolt carrier20. The bumper41will come to rest against the annular side wall25located about the back end32of the bolt carrier20while the distil end45of the shaft42protrudes into the hammer clearance slot26. The distil end45of the shaft42is received by the interior opening44of the cylindrical weight43. The cylindrical weight43is then welded to the shaft42, thereby making the buffer40an integral part of the bolt carrier20. The cylindrical weight43is larger in diameter than the thru bore21housing the shaft42, but smaller in diameter than the countersunk bore24where it is partially received during, at least, the forward movement of the bolt carrier20. Once welded in place, the buffer40still has a limited range of longitudinal movement within the thru bore21of the bolt carrier20.

On the back end32of the bolt carrier20, extending between the boss22and the annular side wall25is the guide rod23. The guide rod is a portion of the bolt carrier20that is smaller in diameter than the boss22. The boss22defines a circular side wall33on its back side. The guide rod portion23of the bolt carrier20is constructed to be received within an interior portion of the buffer spring12, with the forward most portion of the buffer spring12abutting the circular side wall33defined by the boss22. The structure of the guide rod portion23prevents the buffer spring12from binding during operation.

The exterior diameter of the buffer spring12is no larger in diameter than the major diameter of the boss22. This allows the boss22to be in direct contact with an interior portion86of the upper receiver81and the interior bore52of the buffer tube50, without the spring12generating additional undesirable friction. The buffer spring12is able to bias the bolt carrier20into battery by placing its force against the circular side wall33of the boss22. In addition, the guide rod portion23of the bolt carrier20helps to orient and keep the buffer spring12from binding up during the rearward movement of the bolt carrier20.

To use the buffer assembly10with a firearm such as the PDW80shown inFIGS.6A-6G and7, the following steps must be taken. Initially, the housing91of the buttstock assembly90is placed against the back end of the lower receiver83so that the protrusion94on its forward face98engages therewith. The buffer tube50is inserted through the interior bore52of the housing91and threadedly secured to the lower receiver83. The buffer tube50is rotated until the forward face of the circumferential ridge56A (seeFIG.11) comes to rest against the shoulder100of the housing91thereby securing both the buffer tube and the housing of the buttstock assembly90to the lower receiver83. The circumferential ridges56A and56B support the housing of the buttstock. The shoulder stock93with attached guide rods92A and92B may then be secured to the housing91as described above.

After the buffer40is secured to the bolt carrier20as described above, the buffer spring12is attached about the guide rod23portion of the bolt carrier20. When properly seated in place, the forward edge of the spring12will rest against the circular side wall33defined by the boss22. The guide rod portion23of the bolt carrier20, the bumper41and a portion of the buffer40shaft42will be contained within an interior opening defined by the spring's12coils.

The bolt carrier20with attached buffer40and spring12are inserted into an interior portion86opening of the upper receiver81as follows. The interior portion86opening is a longitudinally extending bore configured to receive and facilitate the reciprocating movements of the bolt carrier20during the operation of the firearm80. With the bolt carrier20seated in place, the spring12and a portion of the bumper41will be protruding from the rearward end of the upper receiver81. The upper receiver81is then oriented such than the protruding spring12is in alignment with the interior bore52of the buffer tube50attached to the lower receiver83. The rearward end of the spring12followed by a portion of the bumper41slide into the buffer tube50. With the upper receiver81and lower receiver83now in operational orientation, the front take down pin16A and rear take down pin16B (FIG.6B) are used to removably secure the two receivers together.

Thus the assembly of a firearm80using the new buffer assembly10and buttstock assembly90has been described. By reversing the steps outlined above, the bolt carrier20, buffer40, spring12, and buttstock assembly90may be removed for routine maintenance and repair.

In one embodiment, buffer assembly10provided herein reduces the overall length of the AR15/M16 firearm by approximately 3.29″. In alternate embodiments, the buffer assembly (and its individual components) could be dimensionally scaled up to work with AR15/M16/AR10 type firearms that rely on bolt carriers and buffer tubes of larger dimensions than those discussed herein in regards to the prior art. In doing so a proportionally smaller buffer assembly will be provided for such a firearm than is found in the prior art.

While one embodiment of the bolt carrier20shown is configured for use with a piston operated AR15/M16 type rifle, a bolt carrier modified to work with a more traditional direct impingent gas operating system which relies on a gas tube could be substituted without losing the benefits of the invention described and claimed herein.

A buffer retaining pin and a spring which biases it into place are common throughout the art as it relates to AR15/M16 type rifles. The buffer retaining pin is used to secure the separate buffer320within the buffer tube330(seeFIG.1A) and facilitate the assembly of so equipped firearms. The buffer assembly10described herein does not need a buffer retaining pin. By incorporating the buffer40onto the rear of the bolt carrier20, a buffer retaining pin would serve no purpose. When assembling an AR15/M16 type rifle originally constructed to use a buffer retaining pin, the part should be omitted during the installation of the buffer assembly10described herein.

In an alternate embodiment, the buffer40could be secured to the bolt carrier20by threadedly securing the cylindrical weight43to the shaft42.

In still another alternate embodiment, the bolt carrier20could be machined with the buffer40, or a similarly weighted structure, as an integral part of its back end32.

In still yet another alternate embodiment, a modified buffer having a body portion configured to be received within the thin bore21formed on the back end of a bolt carrier20could be manufactured. The modified buffer could be retained in place by sandwiching it between the back end32of the bolt carrier and the front end of the buffer spring12.

In a further embodiment, the catch115could omit one of the openings124and detents117found along its length to simplify the mechanism.

In a still further embodiment, additional notches may be placed along the length of the guide rods92A and92B to provide for additional positions of adjustment, possibly making the stock more ergonomic for the user.

The foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment. 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.