Patent Publication Number: US-8984791-B1

Title: Adjustable gun stock assembly with modular accessories

Description:
PRIORITY 
     This application claims the benefit of U.S. Provisional Application No. 61/925,047 filed on Jan. 8, 2014, which is hereby incorporated in its entirety. 
    
    
     TECHNICAL FIELD 
     The invention has pertains to assault rifles and more particularly to an expandable butt stock for an assault rifle. 
     BACKGROUND OF THE INVENTION 
     Assault rifles are well known in the art. The civilian version of a semiautomatic rifle is known as the AR15. The AR15 is manufactured in a standard size. This presents a problem because users are of different sizes. The size of the butt stock may be well sized for one user but may not work adequately for a smaller user or larger user. What is needed is an extendable butt stock which can be attached to an AR15 receiver. 
     Existing art has attempted to solve this problem. U.S. Pat. No. 7,398,616 teaches an extendable butt stock. This patent is limited in that it utilizes only a portion of the elongated receiver extension tube  110  to create adjustable positions for the butt stock. In addition, the patent does not teach a system which may be extended or shortened quickly and easily but requires additional time for a user to change the length of the butt stock. What is needed is an extendable butt stock which may be extended and shortened quickly and easily by a user, without the need for screws or the use of tooling by the user. 
     In addition, the prior art is limited in that the prior art teaches extendable butt stocks which are primarily entire structures and cannot be disassembled. This presents a limitation when a user desires to fully disassemble a weapon for cleaning. What is needed is an extendable butt stock which can be easily disassembled and reassembled for cleaning purposes. Furthermore, such a system provides the benefit in that if any part of the structure is damaged then the individual component may be replaced rather than replacing the entire extendable butt stock, as is required with the prior art. 
     Additionally, there are many components which can be utilized with an AR15. Components that can be used with an AR15 can include a picatinny rail, a spike pad for breaking glass, a standard sling mount, a quick disconnect sling mount, rubber base pads, an adjustable cheek rise, an adjustable, rear base extension, among other items. The use of components such as these are normally factory installed on AR15s or require an exordinate amount of time to attach to a standard AR15. What is needed is a quick and efficient method to attach components to an AR15 when needed or desired and a quick and efficient method to remove components when they are no longer required. Therefore, what is needed is an extendable gun stock which allows for the quick and efficient attachment or detachment of modular components. 
     SUMMARY OF THE INVENTION 
     The invention is directed toward a butt stock assembly for a firearm. The butt stock assembly comprises a front cap, a base, a center frame, a tube housing, a release lever, a locking pin, a rotation pin, and a spring. The center frame has a plurality of attachment holes. The attachment holes provide a means for attaching modular firearm components to the butt stock assembly. The release lever comprises a first end and a second end. The release lever is attached to the center frame by the rotation pin. The release lever pivots about the rotation pin. The first end of the release lever pivots in an opposite direction than the second end of the release lever. The release lever engages the locking pin. The locking pin engages the spring. When a user pushes on the first end of the release lever the second end of the release lever pulls the locking pin toward the center frame, compressing the spring. The center frame has a top edge, a front edge, a back edge, and a bottom edge. The front cap is removably secured to the front edge of the center frame. The base is removably secured to the back edge of the center frame. 
     In another embodiment of the invention the tube housing may be placed against the top edge of the center frame. In another embodiment of the invention the center frame may further comprise two side plates positioned on the upper edge of the center frame and integral to the center frame. In another embodiment of the invention the assembly may further comprise two side plates which are removably secured to the upper edge of the center frame. In another embodiment of the invention the center frame may have two attachment holes positioned on the rear end of the center frame which are three inches apart. In another embodiment of the invention the center frame may have two attachment holes positioned on the lower edge of the center frame which are 0.55 inches apart. In another embodiment of the invention the center frame may have two attachment holes positioned on the upper edge of the center frame which are 2.15 inches apart. In another embodiment of the invention the center frame may have two attachment holes positioned on the upper edge of the center frame which are 3.2 inches apart. In another embodiment of the invention the center frame may have two attachment holes positioned on the upper edge of the center frame which are 4.25 inches apart. In another embodiment of the invention the center frame may have two attachment holes positioned on the upper edge of the center frame which are 1.05 inches apart. 
     In another embodiment of the invention the center frame may have four attachment holes positioned on the upper edge of the center frame. In this embodiment the four attachment holes are positioned in a direct line with a foremost hole positioned toward the front end of the center frame. In this embodiment, one attachment hole is 2.15 inches away from the foremost hole, one attachment hole is 3.2 inches away from the foremost hole, and one attachment hole is 4.25 inches away from the foremost hole. In another embodiment of the invention the butt stock assembly may further comprise a plurality of fasteners. In this embodiment the fasteners attach modular firearm components to the attachment holes of the center frame. 
     In another embodiment of the invention the butt stock assembly may further comprise an elongated receiver extension tube. In this embodiment the elongated receiver extension tube is circular and has a first end and a second end. The first end has an external thread complimentary to an internal thread of a receiver of a firearm. When the first end of the elongated receiver extension tube is attached to the receiver of a firearm a user may place the butt stock assembly on the elongated receiver extension tube by placing the second end of the elongated receiver extension tube within the tube housing of the butt stock assembly. In another version of this embodiment the elongated receiver extension tube has a plurality of pin receiver holes. The plurality of pin receiver holes are positioned in a direct line longitudinally along the body of the elongated receiver extension tube. 
     In any embodiment of the invention the components of the butt stock assembly may be make out of aluminum. In any embodiment of the invention the butt stock assembly may further comprise a cheek pad. In any embodiment of the invention the butt stock assembly may further comprise a plurality of sling mounts. 
     The invention is also directed toward a firearm with an expandable butt stock. The butt stock is utilized for attaching a plurality of modular firearm components. The firearm comprises an elongated receiver extension tube, a butt stock assembly, and a plurality of fasteners. The elongated receiver extension tube is circular and has a first end and a second end. The first end has an external thread complimentary to an internal thread of a receiver of a firearm. When the first end of the elongated receiver extension tube is attached to the receiver of a firearm a user may place the butt stock assembly on the elongated receiver extension tube by placing the second end of the elongated receiver extension tube within the tube housing of the butt stock assembly. The elongated receiver extension tube has a plurality of pin receiver holes. The plurality of pin receiver holes are positioned in a direct line longitudinally along the body of the elongated receiver extension tube. The butt stock assembly comprises a front cap, a base, a center frame, a tube housing, a release lever, a locking pin, a rotation pin, and a spring. The center frame has a plurality of attachment holes. The attachment holes provide a means for attaching modular firearm components to the butt stock assembly. The release lever comprises a first end and a second end. The release lever is attached to the center frame by the rotation pin. The release lever pivots about the rotation pin. The first end of the release lever pivots in an opposite direction than the second end of the release lever. The release lever engages the locking pin. The locking pin engages the spring. When a user pushes on the first end of the release lever the second end of the release lever pulls the locking pin toward the center frame, compressing the spring. The center frame has a top edge, a front edge, a back edge, and a bottom edge. The front cap is removably secured to the front edge of the center frame. The base is removably secured to the back edge of the center frame. The center frame has a plurality of attachment holes that provide a means for attaching modular firearm components to the butt stock assembly. The center frame has two attachment holes positioned on the rear end of the center frame. The two attachment holes positioned on the rear end of the center frame are three inches apart. The center frame has two attachment holes positioned on the lower edge of the center frame 0.55 inches apart. The center frame has four attachment holes positioned on the upper edge of the center frame. The four attachment holes are positioned in a direct line with a foremost hole positioned toward the front end of the center frame. One attachment hole is 2.15 inches away from the foremost hole, one attachment hole is 3.2 inches away from the foremost hole, and one attachment hole is 4.25 inches away from the foremost hole. The fasteners attach modular firearm components to the attachment holes of the center frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the gun stock assembly. 
         FIG. 2  is a side view of the gun stock assembly with modular components attached. 
         FIG. 3  is a perspective view of the gun stock assembly with a modular component attached. 
         FIG. 4  is a view of a modular component. 
         FIG. 5  is a view of a modular component. 
         FIG. 6  is an exploded view of the gun stock assembly. 
         FIG. 7  is an exploded view of another embodiment of the gun stock assembly. 
         FIG. 8  is a side view of the gun stock assembly. 
         FIG. 9  is a side view of the gun stock assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The claimed subject matter is now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced with or without any combination of these specific details, without departing from the spirit and scope of this invention and the claims. 
     Referring to  FIG. 1 , the preferred embodiment of the butt stock assembly  100  is displayed. The butt stock assembly  100  is comprised primarily of a front cap  10 , a center frame  20 , a tube housing  40 , a release lever  50 , and a base  30 . The center frame  20  is triangular in shape and preferably has a right angle. When positioned in the butt stock assembly  100 , the right angle of the center frame  20  is positioned toward the top and the rear of the butt stock assembly  100 . The center frame has a hollow triangular center and hollow triangular bracing along the angled portions of the center frame  20  to save expense and cost on material while providing a structurally sound product. The center frame  20  has a plurality of attachment holes  25  throughout the center frame  20 . The attachment holes  25  permit the attachment of modular components to the butt stock assembly  100 . 
     The attachment holes may be located in any position on the center frame  20 . In the preferred embodiment the attachment holes  25  are located in specific, predesigned locations to permit efficient attachment and detachment of modular components. For instance, in the preferred embodiment, there are four attachment holes  25  along the top of the center frame  20 . From the forward most hole the second hole is 2.15 inches away, the third hole is 3.2 inches away, and the fourth hole is 4.25 inches away. Additionally, there are two attachment holes  25  along the base edge of the center frame  20  which are 3 inches apart from each other. Additionally, there are two attachment holes  25  on the bottom of the center frame  20  which are 0.55 inches apart. 
     Any number or type of modular components may be attached to the butt stock assembly  100 . For instance, as displayed in  FIG. 2 , a picatinny rail modular component  300  is attached to the attachment holes  25  along the bottom of the center frame  20 . In addition, there is a removable quick disconnect sling mount  200  attached to the attachment holes  25  along the top of the center frame  20 . As shown in  FIG. 3 , a spike pad modular component  400  attached to the attachment holes  25  on the bottom of the center frame  20 . The spike pad modular component  400  allows a user to break glass with the rear of the AR15. Such a component is desirable if the user is engaged in a police raid or the like. As shown in  FIG. 4 , the modular component attached to the butt stock assembly  100  may be a quick disconnect sling mount  200  which permits a user to quickly remove the gun from a shoulder strap. As shown in  FIG. 5 , the modular component may be a removable standard sling mount  220 . 
     Referring to  FIG. 6 , an exploded view of the butt stock assembly  100  is displayed. The butt stock assembly  100  is comprised of a front cap  10 , a center frame  20 , a base  30 , a tube housing  40 , a release lever  50 , a locking pin  60 , and a rotation pin  70 . The butt stock assembly is held together by a plurality of fasteners  80 . The locking pin  60  has a cross bar  62  to create two horizontal arms. The horizontal arms of the locking pin  60  extend beyond the width of the center frame  20 . The locking pin  60  fits within a spring  64 . The center frame  20  has two side plates  22  extending upward. The tube housing  40  is attached to the top of the center frame on each side of the two side plates  22 . The front cap  10  is structured to receive the front ends of the tube housing  40  and the center frame  20 , including the two side plates  22  of the center frame. The front cap  10  is positioned over front end of the tube housing  40  and attached to the center frame  20  via a fastener  80 . The base  30  is structured to receive the rear end of the tube housing  40  and the center frame  20 , including the two side plates  22 . The base  30  is positioned over the rear end of the tube housing  40  and secured to the center frame  20  via a fastener  80 . The fasteners  80  may be any type of structural fastener able to be removed. Preferably the fasteners  80  are countersunk screws. 
     The release lever  50  attaches to the center frame  20  by means of the rotation pin  70 . The rotation pin  70  passes through a hinge point located in the release lever  50 . The rotation pin  70  is connected to center frame  20 . In the preferred embodiment, the rotation pin attaches to the center frame  20  through the side plates  22 . The release lever  50  has two ends extending from the hinge point, a long end and a short end. The short end of the release lever  50  has two arms which extend toward the front of the firearm. The arms of the release lever  50  extend over the horizontal arms of the locking pin  60 . The long end of the release lever  50  has a press tab. 
     The top edge of the center frame  20  has a recess located approximately one quarter of the length from the front end of the rifle. The recess is of sufficient length and width to receive the locking pin  60 . Interfacing between the locking pin  60  and the center frame  20  is a spring  64 . As the locking pin  60  moves toward the center frame  20 , the spring  64  is compressed. As the locking pin  60  moves away from the center frame  20 , the spring  64  decompresses. 
     The tube housing  40  extends the length of the center frame  20 . The tube housing  40  is substantially circular except that a void exists along the bottom side of the tube housing  40 . The void runs along the length of the tube housing  40 . When the tube housing  40  is attached to the center frame  20  a hollow internal cavity is formed. 
     Referring to  FIG. 7 , an alternative embodiment of the butt stock assembly  100  is displayed. The alternative embodiment is comprised of a front cap  10 , a center frame  20 , a tube housing  40 , two slide plates  22 , a release lever  50 , a cheek pad  42 , a base  30 , a locking pin  60 , a rotation pin  70 , and a plurality of sling mounts  28 . In this embodiment, the two side plates  22  are separate and distinct from the center frame  20 . The two side plates  22  align along the top edge of the center frame  20 . The two side plates  22  are positioned along the sides of the top edge of the center frame  20  and with center frame  20  centered between the two side plates  22 . The two side plates  22  are made up of a left side plate and a right side plate. Along the top edge of the center frame  20  are a plurality of holes extending through the thickness of the center frame  20 . The plurality of holes match a plurality of holes located in the two side plates  22 . The plurality of holes allow for a plurality of fasteners  80  to pass through the side plates  22 , tieing the side plates  22  to the center frame  20 . 
     On the inner edge of each of the two side plates  22 , located approximately one quarter of the way back from the front edge of the two side plates  22  is a recessed groove. Each recessed groove is positioned to match the location of the recess in the center frame  20  which is structured to receive the locking pin  60 . The locking pin  60  has two horizontal arms extending toward the sides. The horizontal arms of the locking pin  60  extend beyond the width of the center frame  20 . 
     Attached to the front end of the butt stock assembly  100  is a front cap  10 . The front cap  10  is structured to receive the front ends of the tube housing  40 , the center frame  20 , and the two side plates  22 . The front cap  10  is attached to the center frame  20  by a fastener  80 . Attached to the rear end of the butt stock assembly  100  is a base  30 . The base  30  is structured to receive the rear end of the tube housing  40 , the center frame  20 , and the two side plates  22 . The base  30  is attached to the center frame  20  by a fastener  80 . 
     On the external surface of the tube housing  40  is placed a cheek pad  42 . The cheek pad  42  is preferably constructed from a synthetic foam. The cheek pad  42  presents a soft surface to protect a user in the instance of recoil when the weapon is fired. Attached to one side of the center frame  20  are a plurality of sling mounts  28 . Preferably there are two sling mounts  28 . The sling mounts  28  allow an individual to attach a sling to the firearm. 
       FIG. 8  displays the butt stock assembly  100  with the elongated receiver extension tube  110 . The elongated receiver extension tube  110  has two ends. The first end has an external thread  112  complementary to an internal thread of a receiver for receiving a butt stock. When threaded into a receiver, the elongated receiver extension tube  110  extends outward from the rear of the receiver. The elongated receiver extension tube  110  has a plurality of pin receiver holes  114  extending along the lower side of the tube. When the elongated receiver extension tube  110  is completely threaded and mated to the receiver, the plurality of pin receiver holes  114  extends in a line located centrally along the center line of the tube. The plurality of pin receiver holes  114  may be in any number and may run partially along the length of the elongated receiver extension tube  110  or may run the entire length of the elongated receiver extension tube  110 . Preferably, each pin receiver hole  114  along the lower side of the tube is uniform in size. Each pin receiver hole  114  is of a size sufficient to receive the locking pin  60  located on the butt stock assembly  100 . In another embodiment of the invention each pin receiver hole  114  may not be a hole, but instead may be a depression into the elongated receiver extension tube  110  sufficient to receive the locking pin  60  such that when the locking pin  60  engages the depression, the butt stock assembly  100  is secured onto the elongated extension tube  110  and does not slide or move. 
       FIG. 9  displays the location of a plurality of attachment holes  25  in the preferred embodiment. The plurality of attachment holes  25  may be located in any position and location on the center frame  20 . In the preferred embodiment there are four attachment holes  25  in a direct line along the top edge of the center frame  20 . The foremost attachment hole  25  is closest to the front cap  10 . One attachment hole is 2.15 inches from the foremost attachment hole  25 . One attachment hole  25  is 3.2 inches from the foremost attachment hole  25 . One attachment hole  25  is 4.25 inches from the foremost attachment hole  25 . In the preferred embodiment there are two attachment holes  25  located at the rear edge of the center frame  20  that are three inches apart. In the preferred embodiment there are two attachment holes  25  located at the lower edge of the center frame  20  that are 0.55 inches apart. 
     The butt stock assembly  100  is structured to internally receive the elongated receiver extension tube  110 . The butt stock assembly  100  secures to the elongated receiver extension tube  110  in a plurality of locations. In this manner the butt stock assembly  100  may be secured in the forward position on the elongated receiver extension tube  110  or secured in the rear position on the elongated receiver extension tube  110 . When the butt stock assembly  100  is placed in the forward position, the total length of the firearm is shorter than when the butt stock assembly  100  is placed in the rear position. Individuals who are smaller in frame and stature would be able to utilize the firearm when the butt stock assembly  100  is positioned in the forward position. Individuals who are larger in frame and stature would be able to utilize the same firearm after positioning the butt stock assembly  100  in the rear position. 
     The components of the butt stock assembly  100  may be composed of any type of material. Preferably the components of the butt stock assembly  100  are composed of aluminum. 
     To utilize the butt stock assembly  100  a user removes the factory installed butt stock from a receiver. The user then threads on the elongated receiver extension tube  110  onto the receiver. The user then places the butt stock assembly  100  onto the elongated receiver extension tube  110 . The elongated receiver extension tube  110  fits within the tube housing  40 . The spring  64  attached to the locking pin  60  pushes the locking pin  60  upward and through the corresponding pin receiver hole  114  in the elongated receiver extension tube  110 . The locking pin  60  thus locks the butt stock assembly  100  in place on the firearm. To move the butt stock assembly  100  along the length of the elongated receiver extension tube  110  a user pushes the press tab on the long end of the release lever  50 . The release lever  50  then hinges around the hinge point such that pushing the press tab upward causes the short end of the release lever  50  to move downward. The two arms on the short end of the release lever  50  push downward on the horizontal arms of the locking pin  60 . This downward pressure pushes the locking pin  60  down into the center frame  20  and compresses the spring  64  attached to the locking pin  60 . This downward motion also removes the locking pin  60  from the corresponding pin receiver hole  114  in the elongated receiver extension tube  110 . The butt stock assembly  100  may then slide forward or backward on the elongated receiver extension tube  110  until the locking pin  60  lines up with a selected corresponding hole in the elongated receiver extension tube  110  to create the desired total length of the firearm. The user then removes pressure from the press tab on the release lever  50 . The spring  64  attached to the locking pin  60  then decompresses and pushes the locking pin  60  through the corresponding hole in the elongated receiver extension tube  110 . 
     To disassemble and reassemble the butt stock assembly  100  a user removes the fasteners  80  from the front cap  10  and the base  30 . The base  30  and front cap  10  may then be removed from the butt stock assembly  100 . Afterward, if the center frame  20  and side plates  22  are separate, the center frame  20  and side plates  22  may be removed from each other and the tube housing  40 . Additional fasteners  80  may need to be removed from the side plates  22  to detach the side plates  22  from the center frame  20 . Any of the components of the butt stock assembly  100  may be replaced while the butt stock assembly  100  is disassembled. While disassembled, a user may clean and oil the components to prolong the useful life cycle of the butt stock assembly  100 . The user may then put the butt stock assembly  100  back together by putting the center frame  20  and tube housing  40  back together (attaching the side frames  22  to the center frame  20  first if they are separate), positioning the front cap  10  and base  30  over the tube housing  40  and center frame  20 , and secure all pieces together with the fasteners  80 . 
     The user may also easily remove and detach modular components to the butt stock assembly  100  as needed or wanted. The modular components may be attached to the butt stock assembly  100  to change the functionality of the butt stock assembly  100 . For instance, modular components such as the picatinny rail  300  or spike pad  400  allow a user to use the butt stock assembly  100  for another purpose. Alternatively, modular components may be attached to the butt stock assembly  100  simply for the purposes of carrying the modular component. The specific modular component may then be used on another location of the firearm when desired. For instance, a bipod or a scope could be attached to the butt stock assembly  100  and attached to the front or top of the firearm when the user desires. When the user is finished using the modular component the user may then reattach the modular component to the butt stock assembly  100 .