Abstract:
A method of locking a handguard relative to an upper receiver of a firearm. The method includes providing a wedge assembly having a top wedge member and a bottom wedge member, each having complementary inclined surfaces; a barrel nut that is configured to receive an outer portion of an upper receiver; and a handguard that is configured to receive the barrel nut and the combined wedge assembly within a lower lip of the handguard. The wedge assembly may include an optional assembly screw and a locator pin where the top wedge member and bottom wedge member are tightly joined to each other via the assembly screw and the locator pin. In use, the lock-up system is used to join the handguard and barrel nut to a corresponding upper receiver with little to no play between the handguard and the upper receiver such that the connection between the two via the wedge assembly is intended to be permanent.

Description:
RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 14/502,702, filed Sep. 30, 2014, entitled “Lock Up System for a Handguard,” the contents of which are fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a method of locking a handguard to an upper receiver of a firearm. 
     BACKGROUND OF THE INVENTION 
     Firearms, particularly high caliber rifles, are manufactured in various components, such as an upper receiver that includes a barrel nut and its corresponding barrel extension, a barrel (discharge end), a bolt carrier, a lower receiver, a butt stock, a trigger, and a handguard. 
     Handguards are popular components of many firearms, particularly AR 15 rifles and military M16s. Handguards extend over the firearm barrel and allow a firearm user to help align the barrel end of the firearm without touching a hot barrel after discharge. Further, handguards generally contain a plurality of external openings in which accessories, like scopes and level devices, can be attached. 
     Handguards generally butt up to and are aligned with the upper receiver. It is desirable to have the connection between a handguard and its corresponding upper receiver be as tight and permanent as possible. However, handguards do not always align end to end as desired and lock up with their corresponding upper receiver and there is resulting “play” between the two components. One option is to buy a one-piece upper receiver/handguard, such as disclosed in U.S. Pat. No. 8,234,808 to Lewis. But manufacturers and OEM manufacturers and some end users like to buy separate handguards and assemble the handguard to the upper receiver post-OEM or in the field. The current known locking systems are bulky in size, difficult to assemble, require laborious timing of the assembly to the upper receiver and can be difficult to remove for updating and maintenance of the rifle. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to an innovative solution for providing a lock-up device, a lock-up system that combines a handguard with the lock-up device, and a method for near permanently joining a handguard to a corresponding upper receiver via a barrel nut assembly and the lock-up device. 
     According to one aspect of the present invention, the lock-up system is directed to a handguard, a barrel nut, and a wedge assembly. 
     The handguard has a first end and a second end with a bore therethrough. The bore is configured to receive the barrel nut. The second end also has a lower lip that is adjacent to the bore. The lower lip has an interior surface that is configured to receive the wedge assembly. 
     The barrel nut is configured to receive a barrel of a firearm. The barrel nut has a first end and a second end. The second end is configured to receive a portion of an upper receiver. The first end of the barrel nut has an outer surface that is configured to be received within the bore. The outer surface may be cylindrical in shape. 
     The wedge assembly includes a top wedge and a bottom wedge. The upper surface of the top wedge has a generally indented surface, which may be concave in shape. The generally indent surface of the top wedge is configured to be biased against the outer surface of the barrel nut. The lower surface of the top wedge is inclined. The bottom wedge has a lower surface configured to be received into and confront the interior portion of the lower lip of the handguard. The upper surface of the bottom wedge is inclined, complementary to the incline of the lower surface of the top wedge. 
     According to another aspect of the present invention, the lock-up system is directed to a combined handguard, upper receiver, barrel nut, and wedge assembly. The barrel nut is affixed to a portion of the upper receiver. Both the upper receiver and handguard have outer edges that closely confront each other in use. The upper receiver has a first end and a second end where the first end closely confronts the second end of the handguard with the barrel nut therebetween mostly positioned within the bore of the handguard. The locked-up handguard and upper receiver may look like a unitary member when assembled. 
     The lock-up system may include an optional assembly screw and locator pin. The optional assembly screw is configured to be positioned within a slot of the inclined upper surface of the bottom wedge and a slot that is abutted by a key in the lower inclined surface of the top wedge. The screw may be tightened to bring and retain the top and bottom wedges into close contact. The locator pin may be used to guide and retain the relative position of the top wedge relative to the bottom wedge. The locator pin is configured to be received within an aperture within the bottom wedge from the lower surface to the inclined surface. 
     Another embodiment includes a wedge assembly having an upper generally indented surface and a lower inclined (angled) surface that is configured to be received within a complementary inclined (angled) interior surface of a lower lip of the handguard. The alternate embodiment wedge assembly may be unitary in construction. 
     Optional fastener or fasteners may be used to retain an exterior portion of the handguard relative to the inserted outer surface of the barrel nut. 
     The present invention also includes a method of locking-up a handguard relative to a corresponding upper receiver. The method includes providing a handguard configured as discussed above. A barrel nut, such as described above is affixed to an external portion of the upper receiver that has outer edges that conform to outer edges of the second end of the handguard. The wedge assembly, as discussed above, is positioned within the lower lip of the handguard with the respective inclined surfaces of the top and bottom wedge in a closely confronting relationship. The two inclined surfaces slide against each other to provide tension and pressure. The bore and indented upper surface of the top wedge, now combined and inserted within the lower lip of the handguard, forms a hollow that conforms to the outer edge of the barrel nut. The barrel nut is squeezed into the hollow space between the upper surface of the top wedge and within the bore. One or more fasteners may be optionally added to secure the wedge to the handguard and the barrel nut outer surface to the handguard. 
     The method of locking-up the handguard relative to the corresponding upper receiver may include the alternate embodiment where the wedge assembly is optionally unitary in nature so that the pressure is maintained when the lower angled surface of the (preferably unitary) wedge assembly is inserted within a handguard that has a lower lip interior surface that has a complementary angled surface to the lower angled surface of the wedge assembly. 
     Similar to the system embodiments, the method may include tightening an optional assembly screw, as well as an optional locator pin to provide further tension and to tighten the bottom wedge to the top wedge. 
     Another optional feature is a partial aperture within each outer edge of the handguard and upper receiver, respectively. The partial aperture is aligned with the corresponding aperture of the other respective member (handguard or upper receiver). The combined entire aperture may incorporate an alignment pin that aligns the upper receiver and the handguard. 
     In this way, the physical connection between the wedge assembly, handguard, and barrel nut is secure and intended to be permanent. 
     These and other advantages are discussed and/or illustrated in more detail in the DRAWINGS, the CLAIMS, and the DETAILED DESCRIPTION OF THE INVENTION. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments. 
       Like reference numerals are used to designate like parts throughout the several view of the drawings, wherein: 
         FIG. 1  is an exploded perspective view of a lock-up system that can include a handguard, a barrel nut, and a lock-up device and where the lock-up device includes a top wedge member, a lower wedge member, and an optional assembly screw and where the lock-up system is used to permanently join the handguard to a corresponding upper receiver and a corresponding barrel extension; 
         FIG. 2  is front assembled view of a combined wedge assembly, comprising the top wedge member, lower wedge member, and optional assembly screw of  FIG. 1 ; 
         FIG. 3  is a section view of the lock-up device taken along section lines  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a section view of a portion of the combined wedge assembly of  FIG. 2  positioned between the handguard and the barrel nut, which is received onto threads of the upper receiver of  FIG. 1 ; 
         FIG. 5  is an unassembled perspective view of the combined wedge assembly, the barrel nut, and a portion of the handguard; 
         FIG. 6  is a left end elevational view of the combined wedge assembly; 
         FIG. 7  is a front right end perspective view of the combined wedge assembly; 
         FIG. 8  is an unassembled perspective view of the wedge assembly; 
         FIG. 9  is a right end elevational view of the combined wedge assembly inserted into the handguard; 
         FIG. 10  is a right end elevational view of an alternate embodiment wedge assembly inserted into a handguard; 
         FIG. 11  is a front section view of an assembled handguard, barrel nut, and alternate embodiment combined wedge assembly taken substantially across lines  11 - 11  of  FIG. 10 ; 
         FIG. 12  is an exploded perspective view of the handguard, barrel nut, and alternate embodiment combined wedge assembly; and 
         FIG. 13  is a rear section view of the assembled handguard, barrel nut, and alternate embodiment of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-9 , according to one embodiment of the invention, the lock-up system of the present invention consists of a handguard  1 , a bottom wedge  2 , a locator pin  3 , a top wedge  4 , an assembly screw  5 , and a barrel nut  6 . The lock-up system is designed to attach to any milspec upper receiver  8  and barrel extension  7 , illustrated in  FIG. 1 . 
     Locator pin  3  is pressed into a hole  101  of bottom wedge  2  such that a diameter  102  of locator pin  3  protrudes from a lower surface  103  of bottom wedge  2 , but not into a slot  104 . Assembly screw  5  is inserted into a threaded a hole  105  of top wedge  4  such that a diameter  106  of assembly screw  5  engages an elongated diameter  107  of top wedge  4 . Top wedge  4  and assembly screw  5  now engage bottom wedge  2  with assembled locator pin  3  such that an inclined (angled) surface  108  of the bottom wedge  2 , and a complementary inclined (angled) surface  109  of the top wedge  4  are in direct contact, and a key  110  of top wedge  4  corresponds to and is positioned within slot  104  of bottom wedge  2 . Further, assembly screw diameter  106  is captured within a cutout  111  of bottom wedge  2 . 
     Referring to  FIG. 2 , the inclined surface of the bottom wedge may be an angle α in the range of 0.5 to 85 degrees, with a preferred range of 1.5 to 4 degrees as measured from an imaginary plane P-P. The top wedge&#39;s complementary inclined surface angle β would be in the range of 0.5 to 85 degrees, with a preferred range of 1.5 to 4 degrees as measured from an imaginary plane P 1 -P 1 . According to one aspect of the present invention, the angle of the inclined lower surface of the top wedge and the angle of the inclined upper surface of the bottom wedge are equal or substantially so that the overall profile of the combined wedge assembly is generally rectangular in shape. 
     Referring particularly to  FIGS. 4 and 5 , the complete wedge assembly ( FIGS. 2 and 3 ) with bottom wedge  2 , top wedge  4 , locator pin  3 , and assembly screw  5  can now be assembled into handguard  1 . The assembly aligns by locating diameter  102  of locator pin  3  into an opening  112  of handguard  1 . Lower surface  103  of bottom wedge  2  seats into a lower lip  115  of handguard  1 . Lower lip  115  defines an interior slot  113  that is accessed through an opening of the handguard. A flat front  114  of top wedge  4  is brought into close proximity of slot  113 /opening of handguard  1 . 
     In use, barrel nut  6  will be fastened onto upper receiver  8  by threads  116  of the barrel nut  6  and threads  117  of the upper receiver  8 , thereby holding the barrel extension  7  in place along with any firearm barrel received therein. Holding the wedge assembly ( FIG. 2 ) into position, a wrench may be inserted through opening  118  in the handguard  1 , thereby adjusting the assembly screw  5 . By turning the assembly screw in a clockwise direction, the screw threads  119  are drawn into the threaded hole  105  of the top wedge  4 . As this proceeds, the screw head surface  120  contacts the capture surface  121  of the bottom wedge  2  in such a way as to impede movement of said screw, independent of the bottom wedge  2 . Since the assembly screw can move no further, being stopped against the capture surface  121  on the bottom wedge  2 , further clockwise rotation of the assembly screw  5  results in motion of the top wedge  4  toward the surface  120  of the assembly screw. 
     The two wedges are held in constant contact by an assembler, causing the surface  108  of the bottom wedge  2  and the surface  109  of the top wedge  4  to be held in contact. The motion of the top wedge  4 , relative to the bottom wedge  2 , commences when assembly screw  5  is turned clockwise. As the smallest ends of each wedge move toward each other, a generally indented, preferably concave, surface  122  of the top wedge  4  moves into closer proximity of the lower surface  103  of the bottom wedge  2 . In general, this means that the concave surface  122  of the top wedge  4  is receding from the open diameter  123  of the handguard  1 . As this loosening of the wedge continues, the top wedge  4  moves in such a way as to bring its forward surface  114  into contact with the interior surface of lower lip  115  of the handguard  1 . A small amount of pressure can be created between these two surfaces (surface  114  and interior surface of lower lip  115 ) by continuing to rotate the assembly screw  5  clockwise a few degrees beyond the point wherein the surface  114  and the interior surface of lower lip  115  are brought into contact causing the wedge to seat itself open and held in position for assembly and confrontation with the barrel nut  6 . At this time, an assembler releases hold of the wedge assembly ( FIG. 2 ), as it is now self-retained. 
     With the conditions described it is now possible to slide the handguard  1  with wedge assembly ( FIG. 2 ) over the barrel nut  6 , which is threaded onto the threaded end of upper receiver  8 . The handguard diameter  123 , which is fashioned to be slightly larger than the diameter  124  of the barrel nut  6 , together with the wedge assembly surface  122 , now forms a relative (e.g., cylindrical) hollow that corresponds to the outer surface diameter)  124  of the barrel nut  6 . The handguard  1 , in combination with the wedge assembly ( FIG. 2 ), now slides onto the barrel nut  6  until confronting contact is made between the handguard  1  and the upper receiver  8  along their respective flat outer edges ( 125 ,  126  of  FIGS. 1 and 4 ). Some form of alignment may be made at this time, such that the addition of an alignment pin  133  extending between aperture  127  and corresponding aperture  128  of the upper receiver  8  and handguard  1 , respectively. 
     Once confronting contact is made between the upper receiver  8  and the handguard  1 , a wrench may be once again inserted through the handguard opening  118  to access assembly screw  5 . By rotating the screw counter-clockwise, a relatively small reverse in the motion of the wedges  2 ,  4  may be achieved when the surface  129  of assembly screw  5  and the capture surface  130  of bottom wedge  2  make contact. Now the assembly screw  5  will not move independent of the bottom wedge  2  as a result of these two surfaces making confrontational contact. The threaded portion of the top wedge  4  will move away from the head of said screw and down the length of the assembly screw&#39;s threaded portion  119 . The relative motion of the two wedges results in the larger ends of each wedge moving closer to each other. Concave upper surface  122  of top wedge  4  and lower surface  103  of bottom wedge  2  move away from each other. As this happens, the concave surface has already been put into biasing contact with the cylindrical diameter  124  of barrel nut  6  as the concave upper surface  122  of top wedge  4  moves toward the relative center of the diameter  123  of handguard  1 . A squeezing force is applied to the outer diameter  124  of the barrel nut  6 . This squeezing force between the handguard inner diameter  123  and the concave upper surface  122  of top wedge  4  that is applied to the outer diameter  124  of the barrel nut  6  affixes the handguard to the barrel nut, holding the relationship between the handguard  1  and the upper receiver  8  near permanently. 
     Once the attachment is completed further fasteners can be applied if desired. Two threaded holes  131  are applied to the sides of the handguard  1  in such a way as to be related to the diameter  123  near the middle of the features&#39; longitudinal length. Two set screws can be threaded into these holes such that they protrude into the inner diameter  123  of the handguard  1  and intersect a radial cut  132  of the barrel nut  6 . The radial cut  132  of barrel nut  6  is angled back toward the upper receiver  8 . As these set screws are tightened into the radial groove  132 , they tend to slide down its angle, being forced toward upper receiver  8 . The result is that handguard  1  is forced toward the upper receiver  8 . No further movement of the handguard toward the upper receiver is possible as the two outer edges  125 ,  126  of handguard  1  and upper receiver  8 , respectively, are already in confronting contact with each other. This additional force has the added benefit of resisting any possible movement of the handguard  1  off of the barrel nut  6 . 
     There are many possible methods of employing wedge surfaces to achieve handguard lock-up of a handguard to a receiver. Above described is a serviceable design and method to achieve this end, but many variations of the wedge surface, its angle, shape, location, and interrelationship to the handguard, barrel nut, and receiver can be created. 
     Many possible permutations of the invention exist. One such permutation is an alternate embodiment illustrated in  FIGS. 10-13 . 
     In this embodiment, handguard  11 , which is substantially the same as handguard  1 , is brought into contact with barrel nut  12  along cylindrical surface  201  of barrel nut  12  and cylindrical surface  202  of handguard  11 . Handguard  11  has a first end and a second end with a bore  210  therebetween. Similar to the first embodiment, handguard  11  has a lower lip  17  with an interior surface  209  that is configured to receive a wedge assembly  16  via end  206  of wedge assembly  16 . 
     Barrel nut  12  is substantially the same as barrel nut  6  in the first embodiment. Barrel nut  12  has a first end and a second end where the first end is configured to receive a portion of an upper receiver (not illustrated in  FIGS. 10-13 ) and a second end has an outer surface (e.g., a cylindrical surface)  201  that is configured to be received axially within bore  210  of the handguard and directly above the lower lip. The interior surface of the lower lip has an inclined surface or surfaces  205  that is complementary to the lower surface(s)  204  of wedge assembly  16 . 
     The wedge assembly  16  in this embodiment is different in that it does not need an assembly screw, a key/slot combination, or a locator pin. Rather, the wedge assembly has an upper generally indented (e.g., concave) surface  203  and an inclined lower surface  204  that is complementary to the inclined surface  205  of handguard  11 . The angles of the inclined surfaces  205  (handguard) and wedge lower surface  204  may be in the same general angled ranges as those discussed in the first embodiment. 
     Concave surface  203  is placed in near contact with cylindrical surface  201  of barrel nut  12 , and inclined surface or surfaces  204  of wedge assembly  16  are simultaneously brought into contact with inclined surface or surfaces  205  of handguard  11  lower lip  17 . In this case, end surface  206  of wedge assembly  16  would begin in its loosened condition in near or exact contact with abutting surface  207  of handguard  11 . As assembly proceeds, opposite end surface  208  of wedge assembly  16  would move rearward toward leading edge surface  209  of handguard  11 . As this action continues, wedge assembly  16  slides across the contact between its inclined surfaces  204  and the inclined surfaces  205  of handguard  11 , causing generally indented (e.g., concave) surface  203  to approach, contact and then pressure the outer (e.g., cylindrical) surface  201  of barrel nut  12 . This pressure exerted effectively causes lock-up of the handguard, wedge and barrel nut. 
     The present invention may include other variants such as a tapered pin and conical slot as an alternate to the first embodiment. In such a variant, the slot would exist in both the barrel nut and handguard, to which the tapered pin could be applied to bring about said wedge pressure to cause handguard to receiver lock-up. 
     These few examples and embodiments, which are by no means exhaustive, are merely intended to illustrate some of the many variations that can occur without departing from the spirit of the invention. 
     Therefore it is the Applicant&#39;s intention that its patent rights not be limited by the particular embodiments illustrated and described herein, but rather by the following claims interpreted according to accepted doctrines of claim interpretation, including the Doctrine of Equivalents and Reversal of Parts.