Patent Publication Number: US-10309747-B2

Title: Firearm rail/handguard and mounting system

Description:
FIELD OF THE INVENTION 
     The disclosure relates to the field of firearm accessories and, more specifically, to an assembly for mounting a modular rail/handguard assembly to a firearm which maintains proper alignment of the assembly with the firearm barrel. 
     BACKGROUND OF THE INVENTION 
     In the general field of combat and commercial weaponry, there is a broad range of accessories available for mounting onto standard firearms in order to upgrade the capability of these weapons. Of particular interest in the context of upgrade accessories is the M16/M4 weapon system that is typically utilized in military or combat settings. Most new models of the M16/M4 weapons also include a dovetail rail interface integrally formed along the top of the upper receiver. This interface rail provides a convenient mounting point for many of the available accessories for use with the M16/M4 firearm, such as scopes, sighting devices, lasers, and directed fire devices. The barrel is held in assembled relation with the upper receiver by a barrel nut that is threaded onto the outside surface of the barrel-receiving receptacle. 
     Some commercially available after market arm rail/handguard assembly systems require permanent modification of the firearm, such as replacing the original barrel nut with a proprietary barrel nut design, before installation thereof, while others are compatible with the existing configuration of the barrel nut provided by the manufacturer. Either way, it is critical during the installation and use of the rail/handguard assembly that the alignment of the rail/handguard assembly longitudinally, axially, and radially relative to the axis of the barrel bore be free from slippage, canting, or other angular displacements, less accessories, such as scopes securable to the rail/handguard assembly not provide true aiming of the firearm. 
     It would therefore be useful to provide a modular rail assembly for use with a firearm that prevents any of longitudinal, axial, or radial misalignment of the modular rail assembly relative to the barrel of the firearm at the time of installation. 
     It would be further useful to provide a modular rail assembly for use with a firearm which prevents any of longitudinal, axial, or radial misalignment of the modular rail assembly relative to the barrel axis of the firearm during use. 
     BRIEF SUMMARY OF THE INVENTION 
     Disclosed is an assembly for mounting a modular rail to a firearm which maintains proper alignment of the modular rail assembly with the firearm barrel. In particular, the disclosure is directed to an improved mounting configuration for attaching the modular rail assembly to the barrel nut of a firearm that prevents any of longitudinal, axial, or radial misalignment of the modular rail assembly relative to the barrel of the firearm during use. The assembly utilizes a biasing element disposed intermediate the barrel nut and the interior diameter of the handguard, a clamping element positioned opposite the biasing element about the perimeter of the barrel nut and having a first wedged surface, and a threaded wedge configured to co-act with the first wedged surface of the clamping element to directionally force the clamping element against the barrel nut in a manner that prevents canting of the handguard. 
     According to one aspect of the disclosure, an assembly apparatus for securing a handguard to a firearm having a cylindrical barrel nut, the assembly system comprises: a handguard having a first end with an interior diameter shaped to receive at least a portion of an exterior of the barrel nut thereagainst; a biasing element disposable intermediate the barrel nut and the interior diameter of the handguard, the biasing element having first and second biasing surfaces disposable adjacent first and second exterior surface portions, respectively, of the barrel nut; a mechanism for securing the biasing element intermediate the handguard and the barrel nut, a clamping element having a first wedged surface and disposable intermediate the barrel nut and the interior diameter of the handguard opposite the biasing element about the barrel nut exterior; and a threaded wedge having a second wedged surface configured to co-act with the first wedged surface of the clamping element to force the clamping element against the barrel nut. In embodiments, the biasing element prevents movement of the handguard longitudinally along the axis of the barrel. In another embodiment, one or both of the biasing element and clamping element have arcuate surfaces disposed adjacent the exterior perimeter of the barrel nut to prevent radial and/or rotational movement of the barrel nut within the interior of the handguard end. In embodiments, the threaded wedge further comprises a threaded aperture extending therethrough for receiving a threaded fastener and the clamping element further comprises a pair of surfaces adjacent the first wedged surface for retaining the threaded wedge in alignment with the clamping element as the second wedged surface of the threaded wedge slides against the first wedged surface of the clamping element while being driven by rotation of the threaded fastener. 
     According to another aspect of the disclosure, an assembly kit for use with a firearm having a barrel nut and a handguard comprises: a biasing element disposable intermediate the barrel nut and an interior diameter of the handguard, the biasing element having first and second biasing surfaces disposed adjacent first and second exterior surface portions, respectively, of the barrel nut; a mechanism for securing the biasing element intermediate the handguard and the barrel nut, a clamping element having a first wedged surface, the clamping element disposable intermediate the barrel nut and the interior diameter of the handguard opposite the biasing element about one of the first and second exterior surface portions of the barrel nut; and a threaded wedge having a second wedged surface configured to co-act with the first wedged surface of the clamping element to directionally force the clamping element against the barrel nut. In embodiments, one or both of the biasing element and clamping element have arcuate surfaces disposed adjacent the exterior perimeter of the barrel nut and prevent radial and/or rotational movement of the barrel nut within the interior of the handguard end. In embodiments, the threaded wedge further comprises a threaded aperture extending therethrough for receiving a threaded fastener and the clamping element further comprises a pair of surfaces adjacent the first wedged surface for retaining the threaded wedge in alignment with the clamping element as the second wedged surface of the threaded wedge slides against the first wedged surface of the clamping element while being driven by rotation of the threaded fastener. 
     According to yet another aspect of the disclosure, a method for mounting a handguard to a firearm having a cylindrical barrel nut, the method comprises: A) disposing a first end of the handguard about a portion of the barrel nut; B) inserting a biasing element intermediate the first end of the handguard and the barrel nut at a first location about an exterior perimeter of the barrel nut; C) inserting a clamping element intermediate the first end of the handguard and the barrel nut at a second location opposite the first location about the exterior perimeter of the barrel nut, the clamping element having a first wedged surface; and D) urging the clamping element against the barrel nut with a movable wedge having a second wedged surface configured to co-act with the first wedged surface of the clamping element. In one embodiment, the threaded wedge further comprises a threaded aperture having a threaded fastener extending at least partially therethrough and journaled with the handguard and wherein D) comprises: D1) rotating the threaded fastener to force the second wedged surface of the threaded wedge to slide along the first wedged surface of the clamping element. 
     For a better understanding of the disclosed system and apparatus, its operating advantages, and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a side, perspective view of an embodiment of the mounting assembly system in accordance with the disclosure; 
         FIG. 2  is a front, end-on view of an embodiment of the mounting assembly system in accordance with the disclosure; 
         FIG. 3  is a bottom, perspective view of the wedged clamping element of the mounting assembly system in accordance with the disclosure; 
         FIG. 4  is a partial, cutaway view of a wedged clamping element and threaded wedge of the mounting assembly system in a released, unclamped configuration in accordance with the disclosure; and 
         FIG. 5  is a partial, cutaway view of a wedged clamping element and threaded wedge of the mounting assembly system in a tightened, clamped configuration in accordance with the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-5  illustrate embodiments of the modular assembly  10  for mounting a rail/handguard in accordance with the disclosure. The mounting assembly  10  comprises a handguard  16 , optional barrel nut  12 , and mounting system  15 . Handguard  16  is the structural element that supports the entire assembly and serves to transfer the loads or additional weight induced by any attachments into the upper receiver of the firearm. Mounting system  15  comprises a clamping element  14 , biasing element  18 , and threaded wedge  25 , which are mechanically coupled intermediate barrel nut  12  and handguard  16 , as well as their respective attachment mechanisms, as described herein in greater detail. 
     As illustrated in the Figures, a cylindrical barrel nut  12  extends longitudinally along an axis  20  and has an exterior perimeter defining first and second exterior surface portions  12 A and  12 B with different exterior diameter values relative to the axis. In the illustrative embodiment, the transition between the diameters of portions  12 A and  12 B is abrupt, causing a step down in the diameter exterior perimeter. In embodiments, barrel nut  12  may have other exterior perimeter surface features as may be designed by the manufacturer of the firearm. Handguard  16  has a first end  16 A with an interior diameter  16 B shaped to receive at least a portion of one of the first and second exterior barrel nut portions  12 A and  12 B thereagainst. 
     Biasing element  18  is disposed intermediate the barrel nut  12  and the interior diameter  16 B of the handguard  16  and has first and second biasing surfaces  18 A and  18 B disposed adjacent the first and second exterior surface portions  12 A and  12 B, respectively, of the barrel nut  12 . In embodiments, the surfaces of biasing element  18  disposed adjacent the exterior perimeter of barrel nut  12 , including one or both of first and second biasing surfaces  18 A and  18 B, may be arcuate in shape with substantially the same degree of curvature as exterior perimeter portion of barrel nut  12  against which the second biasing surfaces  18 A and  18 B are disposed. In the illustrative embodiment, biasing element  18  may have a generally L-shaped length profile, as seen parallel to axis  20 , and may have along a portion of its length a generally U-shaped cross-sectional profile, as seen from a plane normal to axis  20 . Biasing element  18  is disposed opposite clamping element  14  about the interior of inner diameter  16 B of handguard  16 . Biasing element  18  is seated in an indentation in the interior surface of inner diameter  16 B, as illustrated. A pair of axially aligned apertures extending at least partially through both biasing element  18  and handguard  16  may accept a screw  22  or other fastening mechanisms, threaded or not, for securing the biasing element  18  intermediate the handguard  16  and the barrel nut  12 , as illustrated in the Figures. 
     Clamping element  14  is disposed opposite biasing element  18  about the interior of inner diameter  16 B of handguard  16  and is seated in an indentation in the interior surface of inner diameter  16 B. As illustrated in  FIG. 3 , clamping element  14  comprises first and second clamping surfaces  14 A and  14 B, which may be arcuate in shape with substantially the same degree of curvature as barrel nut exterior perimeter portions  12 A and  12 B against which they are disposed, respectively. In the illustrative embodiment, clamping element  14  may also have a generally L-shaped length profile, as seen parallel to axis  20 , and may have along a portion of its length a solid cross-sectional profile, as seen from a plane normal to axis  20 . Clamping element  14  further comprises a wedge surface  14 C formed in the bottom surface thereof facing toward screw  24 . A threaded aperture extends at least partially through handguard  16  and receives screw  24 , as illustrated in the Figures. 
     Mounting system  15  further comprises a threaded wedge  25  having a wedged top surface  25 A which compliments wedge surface  14 C of clamping element  14 . A threaded aperture extends at least partially through threaded wedge  25  and also receives screw  24 , as illustrated in the Figures. When the screw  24  is tightened, threaded wedge  25  travels horizontally along the axis of screw  24 , causing wedged top surface  25 A to slide under wedge shaped surface  14 C of clamping element  14 , forcing clamping element  14  upward and causing one or both of clamping surfaces  14 A and  14 B to engage the exterior perimeter surface of barrel nut  12 , as illustrated in  FIGS. 4-5 . As clamping element  14  puts upward force on barrel nut  12 , the biasing element  18  prevents handguard  16  from canting. In embodiments, clamping element  14  and threaded wedge  25  having complimentary mating features, such as one of a tongue and groove at their respective edges thereof, to facilitate alignment of wedge surface  14 C against wedged top surface  25 A, as threaded wedge  25  travels horizontally along the axis of screw  24 . In embodiments, the clamping element  14  further comprises a pair of surfaces  14 D adjacent the wedged surface  14 C for retaining the threaded wedge  25  in alignment with clamping element  14  as wedged surface  14 C wedge slides against the wedged top surface  25 A of the clamping element  25  as threaded wedge  25  travels horizontally along the axis of screw  24 . In  FIGS. 2, and 4-5 , the clamping element  14  is shown in partial cross section as seen along line  3 - 3  of  FIG. 3  to illustrate the relationship between wedged surface  14 C and wedged top surface  25 A. 
     In practice, the method for mounting a handguard  16  to a firearm having a cylindrical barrel nut  12  comprises first exposing the barrel nut  12  and then disposing a first end of the handguard about a portion of the barrel nut followed by inserting a biasing element intermediate the first end of the handguard and the barrel nut at a first location about an exterior perimeter of the barrel nut and inserting a clamping element intermediate the first end of the handguard and the barrel nut at a second location opposite the first location about the exterior perimeter of the barrel nut, the clamping element having a first wedged surface. Thereafter, the clamping element is urged or secured against the barrel nut with a movable wedge having a second wedged surface configured to co-act with the first wedged surface of the clamping element. Because the threaded wedge comprises a threaded aperture having a threaded fastener extending at least partially therethrough and journaled with the handguard, rotating the threaded fastener will force the second wedged surface of the threaded wedge to slide along the first wedged surface of the clamping element. 
     Because both biasing element  18  and clamping element  14  mimic the abrupt transition between the diameters of barrel nut  12  between surfaces  12 A and  12 B, the longitudinal cross-sectional profiles of both biasing element  18  and clamping element  14  along axis  20  are generally L-shaped and prevent of longitudinal misalignment of the handguard assembly relative to axis  20  of barrel nut  12  at the time of installation and during use. Similarly, because biasing surfaces  18 A and  18 B of biasing element  18  and clamping surfaces  14 A and  14 B of clamping element  14  have arcuate surfaces that mimic the respective curvatures of surfaces  12 A and  12 B of barrel nut  12  with which contact is made, axial and/or radial misalignment of the handguard  16  relative to barrel nut  12  is prevented at the time of installation and during use. 
     Handguard  16  may be formed generally as a tubular enclosure that is configured to encircle the barrel of the firearm when assembly  10  is installed on the firearm in a mounted position. In the illustrative embodiments, handguard  16  has a unitary or monolithic construction defined by left and right side walls that extend between ends thereof and generally outwardly and downwardly in an arcuate manner from an integrally formed top dovetail rail to form a substantially cylindrical body. Top dovetail rail extends at least partially longitudinally between the forward end and the rearward end. An optional supplemental dovetail rail interface may be slidably attached to the bottom of handguard  16  utilizing an integrally formed projection having a complimentary mating cross-sectional profile. 
     In the embodiments, any elements of assembly  10  and mounting system  15  may be formed of substantially rigid materials including steel, stainless steel, aluminum, ceramics, or other materials capable of withstanding heat generated by the barrel nut  12  during use of the firearm. 
     As illustrated in the Figures, side walls of the handguard  16  may have a plurality of wall vents extending therethrough to facilitate cooling of the firearm barrel by allowing heated air from the interior of handguard  16  to escape through the vents. It will be obvious to those reasonably skilled in the art that any configuration or shape of sidewall vents, including an open lattice structure, may partially define one or both of sidewalls. It will be further obvious to those reasonably skilled in the art that handguard  16  may have other cross-sectional profiles, such as a pentagon or octagon or other configuration. In addition, although handguard  16  in the illustrative embodiment forms an integral sleeve-like structure, it is contemplated herein that one or more constituent components thereof may be separately assembled into a sleeve-like structure which is insertable over the open end of barrel. 
     While the fasteners illustrated with regard to the illustrative embodiments, including screws  22 , have been shown to be conventional threaded screws, other fastening mechanisms may be equivalently substituted. For example, screws  22  may be replaced with a combination of helicoil inserts and threaded fastening mechanisms. Such helicoil inserts may have threaded exteriors for coupling with threaded interiors of apertures which extend through the handguard  16 . The helicoil inserts may also have a threaded interior which can couple with the threaded exterior of screw  22  or other fastening mechanisms. In some cases, such helicoil inserts may be formed from a stronger and more rigid material than the handguard  16  (i.e. steel versus aluminum) to prevent the handguard  16  from warping, crushing, or otherwise deforming due to force through the fastening mechanisms. In embodiments, the lower surfaces of the fastening mechanisms and the surfaces with which they have contact may be flat to maximize contact area. 
     While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.