Patent Publication Number: US-10330433-B2

Title: Composite handguard for a firearm and mounting/attachment apparatus therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. non-provisional application Ser. No. 14/747,005 filed Jun. 23, 2015, which claims the benefit of U.S. provisional application No. 62/015,626, filed Jun. 23, 2014, the entire content of each of which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to relates to firearms, and more particularly relates to a handguard for a firearm, as well as a mounting/attachment apparatus to mount and attach the handguard to the firearm. 
     BACKGROUND 
     Certain firearms, such as certain semi-automatic and automatic firearms in the family of AR-15/M16 firearms, may include a tubular handguard which surrounds at least a portion of the length of the barrel. 
     Among other functions, the handguard may protect the firearm operator&#39;s hand from a heated barrel after the firearm is fired, particularly by inhibiting the operator&#39;s hand from contacting the barrel directly and subsequently suffering a burn or other injury. The handguard may also protect the barrel and other parts of the firearm contained therein from being damaged during use of the firearm. 
     The handguard may be made of metal, particularly aluminum. However, in response to extreme use of the firearm, a metal handguard may be understood to heat-up due to the high thermal conductivity of the metal, and thus defeat the objective of protecting the firearm operator&#39;s hand from heat associated with the barrel after the firearm is fired. 
     In order to address the problems associated with the heating of metal handguards, injection molded thermoplastic polymer handguards have been developed. However, while addressing the problems associated with the heating of metal handguards, the injection molded thermoplastic polymer may not offer adequate strength or other physical properties, such as impact resistance or heat resistance. 
     In order to increase either the impact resistance and/or heat resistance of an injection molded thermoplastic polymer, fiber reinforcement may be added to the injection molded thermoplastic polymer to provide a fiber-reinforced thermoplastic handguard. 
     However, a fiber-reinforced thermoplastic polymer, while possibly offering an increase in impact resistance and heat resistance as compared to an unreinforced thermoplastic polymer, still may suffer from impact resistance and heat resistance limitations as the fiber length of injection molded fiber reinforced thermoplastic polymers is generally less than 10 mm, and more commonly less than about 3 mm, due to the screw of the injection molding machine tending to break the fibers as they are processed within the barrel. Furthermore, fiber loading levels may generally be limited to about 20-30% by weight. 
     Many handguards also require custom mounting, which requires modification of the firearm in order to install the handguard. 
     SUMMARY 
     The present disclosure provides plastic composite handguards, particularly formed with long fiber reinforced plastic composite for added strength (impact) and heat resistance. 
     The handguards may include an accessory mounting rail. The accessory mounting rail may include an inner elongated rail segment located beneath the fiber reinforced plastic composite which extends longitudinally along a length of the mounting rail. 
     The handguard may be mounted to the firearm using a handguard mounting member which overlies a barrel nut of the firearm. 
    
    
     
       FIGURES 
       The features of this disclosure, and the manner of attaining them, will become more apparent and better understood by reference to the following description of embodiments described herein taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a side view of a firearm which includes a handguard and a mounting/attachment apparatus according to the present disclosure; 
         FIG. 2  is a front perspective view of the firearm of  FIG. 1 ; 
         FIG. 3  is an enlarged side view of the portion of the handguard of the firearm of  FIG. 1  bounded by rectangle  3 ; 
         FIG. 4  is a cross-sectional view of the handguard of the firearm of  FIG. 1  taken along line  4 - 4  of  FIG. 1 ; 
         FIG. 5  is an enlarged cross-sectional view of the portion of the handguard of  FIG. 4  bounded by circle  5 ; 
         FIG. 6  is an enlarged side view of an another embodiment of the handguard of the firearm of  FIG. 1  according to the present disclosure; 
         FIG. 7  is a cross-sectional view of an elongated insert for another embodiment of the handguard of the firearm of  FIG. 1  according to the present disclosure; 
         FIG. 8  is a cross-sectional view of another embodiment of the handguard of the firearm of  FIG. 1  taken along line  4 - 4  of  FIG. 1  including the insert of  FIG. 7 ; 
         FIG. 9  is a perspective view of a handguard mounting/attachment apparatus which may be provided with or otherwise utilized with a handguard according to the present disclosure, particularly to mount and attach the handguard to the firearm; 
         FIG. 10  is a perspective view of a conventional barrel nut for an AR-15/M16 firearm according to the prior art; 
         FIG. 11  is a perspective view of another embodiment of a handguard mounting/attachment apparatus which may be provided with or otherwise utilized with a handguard according to the present disclosure, which may comprise first and second mounting members; 
         FIG. 12  a perspective view of a one of the mounting members of the handguard mounting/attachment apparatus of  FIG. 11 ; 
         FIG. 13  another perspective view of a one of the mounting members of the handguard mounting/attachment apparatus of  FIG. 11 ; 
         FIG. 14  is a perspective view of the handguard mounting/attachment apparatus of  FIG. 11  coupled with the barrel nut of  FIG. 10  on an AR-15/M16 firearm; 
         FIG. 15  is another perspective view of the handguard mounting/attachment apparatus of  FIG. 11  coupled with the barrel nut of  FIG. 10  on the AR-15/M16 firearm; 
         FIG. 16  is a side view of a handguard according to the present disclosure slideably and partially engaging over the handguard mounting/attachment apparatus of  FIG. 11  and barrel nut of  FIG. 10  on the AR-15/M16 firearm; 
         FIG. 17  is a side view of a handguard according to the present disclosure slideably and fully engaging over the handguard mounting/attachment apparatus of  FIG. 11  and barrel nut of  FIG. 10  on the AR-15/M16 firearm; and 
         FIG. 18  is a perspective view of another embodiment of a handguard mounting/attachment apparatus which may be provided with or otherwise utilized with a handguard according to the present disclosure, which may comprise first and second mounting members. 
     
    
    
     DETAILED DESCRIPTION 
     It may be appreciated that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention(s) herein may be capable of other embodiments and of being practiced or being carried out in various ways. Also, it may be appreciated that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting as such may be understood by one of skill in the art. 
     Referring now to  FIGS. 1-2 , there is shown a firearm  10  according to the present disclosure. As shown, the firearm  10  may comprise a gas-operated semi-automatic or full-automatic firearm. The gas operated system may be a direct gas impingement system, or a gas operated piston system. The direct gas impingement system directs hot propellant combustion gas from a fired cartridge directly to a bolt carrier to cycle the action of the firearm. More particularly, the gas pressure of the combustion gas pushes the bolt carrier rearward against the bias of a buffer spring, during which time the fired cartridge case is extracted from the chamber of the barrel and ejected from the firearm. As the gas pressure dissipates, the compressed buffer spring then decompresses and pushes the bolt carrier forward, during which time an unfired cartridge is removed from the magazine and loaded into the chamber of the barrel. In contrast to a direct gas impingement system, with a gas operated piston system, the gas forces a piston rod of a piston and the bolt carrier rearward to handle the extraction and ejection process, and thereafter the bolt carrier is forced forward by a decompression of the buffer spring to the closed position just as with direct impingement. 
     Even more particularly, firearm  10  may be a member of the family of AR-15/M16 firearms, which may include the AR-10, AR-15, M16, M16A1, M16A2, M16A3, M16A4, M4, M4A1, CAR-15, etc. Firearm  10  may also include a submachine gun, a compact assault rifle or a machine pistol. Firearm  10  may be configured to fire rifle cartridges (e.g. the 5.56×45 mm NATO military cartridge, 5.56/.223 Remington, 300 Blackout, 0.308 Win/7.62×51, 5.45×39, 7.62×39, 458 SOCOM, and 0.50 Beowulf) as well as pistol cartridges (9 mm). Firearm  10  may be categorized as a rifle, a carbine, a mid-length or a pistol, particularly depending on barrel length. 
     As shown, firearm  10  includes a receiver  12  comprising a lower receiver  14  and mating upper receiver  16 . Upper receiver  16  includes bolt carrier  30  including a firing pin, as well as a cartridge loading and unloading mechanism. A barrel  40  is affixed to the front end of upper receiver  16  and a butt stock  50  is affixed to the rear end of lower receiver  14 . A trigger portion of upper receiver  16  fits into an access opening in lower receiver  14  and is integrated with the internal mechanism of upper receiver  16  and lower receiver  14 . A pistol grip  60  is attached to lower receiver  14 . A detachable (removable) box magazine as known in the art (not shown) may be inserted into a magazine receptacle  18  having a downwardly oriented access opening in lower receiver  14  for feeding cartridges to the cartridge insertion and ejection mechanism within upper receiver  16 . The detachable magazine is capable of being loaded and unloaded while detached from firearm  10 , and holds the cartridges side-by-side in one or more columns/rows, which may be staggered. In certain embodiments, the detachable magazine may also comprise a drum magazine in which the cartridges are positioned and fed in an unwinding spiral. 
     A handguard  80  is affixed at the front end of upper receiver  16 , either to the upper receiver  16  or the barrel  40 . Handguard  80  includes an elongated tubular body  82 .  FIG. 3  shows an enlarged view of the portion of tubular body  82  bounded by the area of rectangle  3  of  FIG. 1 , while  FIG. 4  shows a cross section of the tubular body  82  taken along line  4 - 4  of  FIG. 1 . 
     As shown by  FIG. 4 , the tubular body  82  may have a substantially octagonal (i.e. having 8 sides) shaped cross-section. It will of course be understood that the cross-sectional profile could be oval, square, rectangular, or any cylindrical configuration which is hollow so as to surround at least a portion of the barrel  40  of firearm  10  without coming in contact therewith along the length of the barrel  40  or the combustion gas return tube  42  that is surrounded. The length of tubular body  82  of handguard  80  may particularly be such that, when mounted on firearm  10 , it extends from the front surface of the upper receiver  16  of the firearm  10  to a distance short of the end of the barrel  30  for easy and convenient gripping by the firearm operator and for protection of the operator&#39;s hand from the barrel  40 . Handguard  80 , and more particularly the tubular body  82 , may also serve as a platform to mount accessories to the fore-end of the firearm  10 , such as by providing one or more accessory mounting rails as discussed herein. As shown, the tubular body  82  of the handguard  80  may be provided by as a single piece tubular member. 
     As shown, tubular body  82  defines an elongated center passage  84  to contain the barrel  40 , as well as certain other components (e.g. the combustion gas return tube or other accessories/features that may be incorporated at some future time) depending on the type of firearm  10 . Tubular body  82  has an outer surface  86  and an inner surface  88 , and may include a plurality of rows of apertures  90  formed therein, particularly to vent heat away from the barrel  40 . While the apertures  90  are shown as having a circular shape, the apertures  90  may have any geometric shape including oval, ellipse, triangle, square, rhombus, diamond, rectangle, pentagon, hexagon, heptagon, octagon, etc. The apertures  90  may be formed in the tubular body  82  after the handguard  80  is molded as discussed in greater detail below. 
     The top side  92  of the handguard  80 , and the tubular body  82 , may include an elongated accessory (mounting) rail  94 , which provides a mounting platform for accessories (e.g., scope). As shown by  FIG. 4 , elongated rail  94  has a T-shaped cross-sectional profile (transverse to the longitudinal axis LA of the handguard  80 ). Elongated rail  94  may more particularly be a Weaver rail or a Picatinny rail, comprising a plurality of alternating equally spaced parallel ribs  96  and slots  98  extending transverse to the longitudinal axis LA of the handguard  80 . 
     Referring now to  FIG. 5 , handguard  80 , and more particularly wall  83  forming tubular body  82 , may be formed of a composite material comprising a plurality of constituent components. More particularly, the composite material may be a fiber reinforced plastic composite material, in which a reinforcement structure  100  in fiber form is embedded in a matrix (binder) composition  110  which comprises at least one polymer. The reinforcement structure  100  may also be referred to as the discontinuous phase while the matrix composition  110  may be referred to as the continuous phase. The composite material of the present disclosure may provide a handguard  80  formed of a thermal (non-conductive) insulator which provides high heat resistance, high impact strength and protects the operator&#39;s hand from the heat of the barrel  40 , as well as inhibits the rail  94  as disclosed herein from heating, possibly adversely effecting the operation of any accessories mounted thereon. 
     The matrix composition  110  may be a thermoset matrix composition formed of at least one thermoset polymer. Exemplary thermoset polymers may include polyester, epoxy, vinyl ester, methyl methacrylate and phenolic. The matrix composition  110  may be optically opaque, translucent or transparent. When optically translucent or transparent, the reinforcement structure  100  may be visible from outer surface  86  or inner surface  88 . The matrix composition  110  may also include a colorant, which may be in the form of a pigment or a dye, which colors the matrix composition  110 . The matrix composition may be colored with a camouflage color, such as a brown (earth) tone or a tan (sand) tone or a green (vegetation) tone. 
     The reinforcement structure  100  may particularly comprise at least one pre-manufactured fiber reinforcement layer  102 , which is embedded in the matrix composition  110 . A pre-manufactured fiber reinforcement layer may be understood as a fiber reinforcement layer which is first formed into a reinforcement layer separate from the matrix  110 . Such would not include, for example, loose, random fibers which are packaged as such. 
     More particularly, the at least one fiber reinforcement layer  102  may comprise a plurality of fiber reinforcement layers  102 ,  104 ,  106  and  108 . As shown by  FIG. 5 , fiber reinforcement layer  102  is shown to be an outer reinforcement layer, reinforcement layer  104  is shown to be an inner reinforcement layer and reinforcement layers  106 ,  108  are shown to be intermediate reinforcement layers between outer reinforcement layer  102  and inner reinforcement layer  104 . 
     Any one or all of the fiber reinforcement layers  102 ,  104 ,  106  and  108  may be provided by a tubular fiber reinforcement member, which is particularly provided without a terminating edge or a seam extending in the longitudinal direction of the tubular reinforcement member (which may be understood to be in the same as the longitudinal axis LA of the handguard  80 ). More particularly, any one or all of the reinforcement layers  102 ,  104 ,  106  and  108  may be provided by a tubular braided and/or woven fabric sleeve. For example, any or all of the fiber reinforcement layers  102 ,  104 ,  106  and  108  may comprise a braided fiber sleeve where the fibers (continuous) are arranged (woven) in a multi-directional (biaxial) braid such that the braided fiber bundles (braid yarns or strands) are arranged off-axis, i.e. at an angle of +/−45 degrees) relative to the longitudinal axis LA of the tubular sleeve. Stated another way, the fibers are not arranged parallel to a longitudinal axis LA of the tubular body  82 . In such a manner, the fiber orientation may provide for balanced control of torsional and longitudinal loads placed on the handguard  80 . Also, while the tubular braided sleeve may be manufactured with the fiber bundles at +/−45 degrees, the actual orientation in the molded tubular body  82  may be broader (due to stretching or other shaping of the tubular braided sleeve), such as within a range of in a range of +/−30 degrees to +/−60 degrees. 
     Any one or all of the reinforcement layers  102 ,  104 ,  106  and  108  may also comprise a woven fiber sleeve where the fibers (continuous) are arranged (woven) such that the fiber bundles (braid yarns or strands) are arranged multi-directionally, particularly longitudinally (0 degrees) and transversely (90 degrees), relative to the longitudinal axis LA of the tubular sleeve. Stated another way, the fibers are arranged parallel and perpendicular to a longitudinal axis LA of the tubular body  82 . 
     Any one or all of the fiber reinforcement layers  102 ,  104 ,  106  and  108  may also be provided by a fiber mat, which may be a continuous strand mat or a chopped strand mat. 
     While it may be preferred that each of the fiber reinforcement layers  102 ,  104 ,  106  and  108  are provided by independent (discrete) members, fiber reinforcement layers  102 ,  104 ,  106  and  108  may also formed by a single mat which is wrapped in a coil to provide the fiber reinforcement layers  102 ,  104 ,  106  and  108  is overlying/underlying relationship. 
     Any one or all of the reinforcement layers  102 ,  104 ,  106  and  108  may be made of glass fibers, carbon fibers or a combination thereof. In a particular embodiment, reinforcement layers  104 ,  106  and  108  may be made of carbon fiber, while reinforcement layer  102  is made of glass fiber. In another embodiment, reinforcement layers  102 ,  104  and  108  may be made of carbon fiber, while reinforcement layer  106  made of glass fiber. The weight/area and the diameter of the layers  102 ,  104 ,  106 ,  108  may vary depending on the particular application of the handguard  80  and the type of firearm  10 . 
     With regards to fiber loading, the tubular body  82 , may have a fiber content in a range of 30% to 60% by weight of the tubular body  82 , and more particularly have a fiber content in a range of 35% to 55% by weight of the tubular body  82 . The fibers may comprise 80-95% by weight carbon fibers and 5%-20% by weight glass fibers. The tubular body may have a thickness in a range of 0.5 mm to 10 mm, and more particularly have a thickness in a range of 2 mm to 5 mm. 
     The handguard  80 , and more particularly the tubular body  82 , may be formed by a closed mold (i.e. two-sided) molding process, such as resin infusion molding process where the matrix composition (e.g. polymer resin) is introduced into a mold containing the preplaced/preloaded reinforcement structure  100 . More particularly, the resin infusion molding process may be a resin transfer molding process, which may be vacuum (i.e. less than atmospheric pressure) or pressure (i.e. greater than atmospheric pressure) assisted, to obtain a tubular body  82  with low void content and high fiber loading. 
     As part of the process, a mold may be provided which has at least one molding cavity to form the tubular body  82 , with the molding cavity being defined by opposing mold halves which may be referred to as the core half and cavity half. The molding process may begin by opening the mold and placing the inner reinforcement layer  104  over an elongated core half of a mold, which may be referred to as the mandrel. The intermediate layer  108  may then be placed over the inner layer  104 , followed by intermediate layer  106  and the outer layer  102  placed over the intermediate layer  106  to form a four layer reinforcement structure  100 . The mold may then be closed and clamped. 
     In alternative embodiments the reinforcement layers  102 ,  104 ,  106  and  108  may be formed to a preformed shape of the tubular body  82  before being placed in the mold, such as being formed over a performing mandrel and then sprayed with a stiffening agent such as starch. The reinforcement layers  102 ,  104 ,  106  and  108  may then all be introduced to the molding cavity simultaneously. 
     The matrix composition  110  may then introduced into the molding cavity (e.g. pumped in under pressure greater than gravity), such as while in the form of a catalyzed low viscosity polymer resin. The matrix composition  110  flows through the molding cavity and the interstices of the reinforcement layers  102 ,  104 ,  106  and  108  while displacing air from the molding cavity. Air may be displaced from the molding cavity through one or more molding cavity vents formed in the mold, or a vacuum may be drawn on the molding cavity to remove air from the molding cavity as well as assist helping the matrix composition  110  flow through the molding cavity and reinforcement layers  102 ,  104 ,  106  and  108  located therein. 
     After the matrix composition  110  has filled the mold and undergone a suitable cure time, the mold may be opened and the handguard  80  comprising the tubular body  82  removed from the mold. The tubular body  82  may then be trimmed and apertures  90  formed (cut) therein. Alternatively the apertures  90  may be formed therein during molding. 
     As an alternative to resin transfer molding, other resin infusion molding processes which may be used to manufacture the handguard  80  of the present disclosure may include structural reaction injection molding, which may particularly make use of a thermoset polymer such as a polyurethane which is processed through a reaction injection molding mixhead. 
     Another closed mold (i.e. two-sided) molding process which may be used to produce handguard  80 , particularly tubular body  82 , may be compression prepreg process in which a reinforcement structure is saturated with a matrix composition  110  (a/k/a pre-impregnation), which is then compression molded with heat and pressure to form the molded article. 
     In the foregoing embodiment of the handguard  80 , the ribs  96  and slots  98  forming the elongated rail  94  may be formed in the tubular body  82  during molding. Alternatively, the ribs  96  and slots  98  may be formed after molding the tubular body  82  by milling otherwise cutting the slots  98  into the tubular body  82 , thereby forming the ribs there between. 
     In another embodiment of the handguard  80  of the present disclosure, as shown in  FIG. 6 , a lower elongated rail segment  120  may be formed by the tubular body  82  which has a planar upper surface  122 , and an upper elongated rail segment  130  may be formed separately from the tubular body  80  (i.e. preformed before manufacture of the tubular body  80 ), with the separately formed upper elongated rail segment  130  having a planar lower surface  132 , as well as preformed ribs  96  and slots  98 . The separately formed upper elongated rail segment  130  may be formed of metal (e.g. aluminum, steel, titanium), or a plastic (e.g. a composite as disclosed herein, or injection molded from a thermoplastic composition). 
     The planar lower surface  132  of the upper elongated rail segment  130  may be coupled to the planar upper surface  122  of the lower elongated rail segment  120  particularly by adhesive bonding with a separate bonding agent located there between. Alternatively, adhesive bonding the upper elongated rail segment  130  to the lower elongated rail segment  120  may be accomplished using the matrix composition  110 . 
     Such may be accomplished by placing the upper elongated rail segment  130  in the forming mold for the tubular body  82 , such as by positioning the upper elongated rail segment  130  on the cavity half of the mold, prior to introducing the matrix composition  110 . Thereafter, when the matrix composition  110  is introduced into the molding cavity and the lower elongated rail segment  120 /tubular body  82  is formed, the upper elongated rail segment  130  becomes a molded-in insert, which may also be referred to as inserted molded, during molding of the tubular body  82  which is bonded directly to the matrix composition  110  during molding. Alternatively, such may also be accomplished after tubular body  82  and the lower elongated rail segment  120  are formed by removing the tubular body  82  from the mold before the matrix composition  110  of the tubular body  82  has reach full cure, in which case the upper elongated rail segment  130  may be pressed onto the lower elongated rail segment  120  and bonded thereto while the matrix composition  110  of the tubular body  82  is still curing. 
     Alternatively, the separately formed upper elongated rail segment  130  may be mechanically coupled, rather than adhesively coupled, to the lower elongated rail segment  120  with a detachable mechanical fastener (e.g. a threaded fastener such as a screw) or a non-detachable mechanical fastener (e.g. a rivet). 
     In another embodiment of the handguard  80  of the present disclosure, as shown in  FIG. 7 , elongated rail  94  may include an inner elongated rail segment  140  which, similar to upper elongated rail segment  130 , may be separately formed from the tubular body  80  (i.e. preformed before manufacture of the tubular body  80 ). The separately formed inner elongated rail segment  140  may be formed of metal (e.g. aluminum, steel, titanium), or a plastic (e.g. profile extruded from a thermoplastic composition). 
     The inner elongated rail segment  140  may be used to eliminate any need for a separately formed upper elongated rail segment  130 , as will become more evident from the disclosure herein. Similar to the first embodiment of the disclosure, the ribs  96  and slots  98  forming the elongated rail  94  may be formed in the tubular body  82  during molding without need for the separately formed upper elongated rail segment  130 . Alternatively, the ribs  96  and slots  98  may be formed after molding the tubular body  82  by milling otherwise cutting the slots  98  into the tubular body  82 , thereby forming the ribs there between. However, it should be recognized that the present disclosure does not preclude the upper elongated rail segment  130  from being used in conjunction with the preformed inner elongated rail segment  140 . It should be understood that when the rail  94  is formed of a lower elongated rail segment  120  and a separate molded-in or attached upper elongated rail segment  130 , the inner elongated rail segment  140  will be part of the lower elongated rail segment  120 . 
     Referring briefly to  FIG. 4 , as shown the elongated rail  94  may have a thicker cross-sectional profile, to increase stiffness, than the remainder of the tubular body  82  of the handguard  80 . As a result, depending on the loft and weight of the reinforcement structure, the reinforcement structure  100  may be further from the outer surface  86  of the rail  94  than for the remaining thinner portion of the tubular body  82 , resulting in an outer portion of the rail thickness being formed predominately of the matrix composition  110  with little or no reinforcement structure  100 . 
     In order to overcome the foregoing difficulty and geometrical challenges of the used materials, inner elongated rail segment  140  may be placed in the mold, such as by positioning the inner elongated rail segment  140  on the core half of the mold, prior to introducing the reinforcement structure  100 . This will, in effect, decrease the thickness of the molding cavity used to form rail  94 . Thereafter, when the reinforcement structure  100  is placed on the core half of the mold, the reinforcement structure  100  will overlie the inner elongated rail segment  140 , which will force the reinforcement structure  100  closer to the outer surface  86  of the handguard  80 . Thereafter, when the matrix composition  110  is introduced into the molding cavity and the tubular body  82  is formed, the inner elongated rail segment  140  becomes a molded-in insert during molding of the tubular body  82  which is bonded directly to the matrix composition  110  during molding. In addition to the inner elongated rail segment  140  positioning the reinforcement structure  100  closer to the outer surface  86  of the handguard  80 , in such fashion the inner elongated rail segment  140  will be enclosed and protected towards the inside of the rail  94  by the reinforcement structure  100 , as well as increase the stiffness of the rail  94 . 
     In another embodiment of the handguard  80  of the present disclosure, as shown in  FIG. 9 , the handguard  80  may include mounting/attachment apparatus  146  configured to mount and attach the handguard  80  to firearm  10 , particularly between the upper receiver  16  and the barrel  40  of firearm  10  via a barrel nut  163  as shown in  FIG. 10 . The mounting/attachment apparatus  146  may be formed of metal (e.g. aluminum, steel, titanium), or a plastic (e.g. a thermoset composite as disclosed herein, or injection molded from a thermoplastic composition). The mounting/attachment apparatus  146  and the handguard  80  may attach to the firearm  10  in a manner as disclosed in U.S. Pat. No. 8,037,633 entitled “Handguard System For Firearms” and/or U.S. Pat. No. 8,464,457 entitled “Firearm Handguard System”, both assigned to the assignee of the present disclosure and both hereby incorporated by reference in their entirety. 
     As shown, mounting/attachment apparatus  146  may have an outer profile  152  (sides/surfaces) which substantially conforms or matches to the inner profile  89  ( FIG. 8 ) of the tubular body  82 . The mounting/attachment apparatus  146  may be coupled to the handguard  80  by being located within the elongated center passage  84  and interference (press-fit) against tubular body  82 . Alternatively, the outer profile  152  of the mounting/attachment apparatus  146  and/or the inner profile  89  of the tubular body  82  may be coated with a bonding agent to form an adhesive bond therebetween. Alternatively, adhesive bonding the mounting/attachment apparatus  146  to the tubular body  82  of the handguard  80  may be accomplished using the matrix composition  110 . 
     Such may be accomplished by placing the mounting/attachment apparatus  146  in the forming mold for the tubular body  82 , such as by positioning the mounting/attachment apparatus  146  on the core half of the mold, prior to introducing the matrix composition  110 . Thereafter, when the matrix composition  110  is introduced into the molding cavity and the tubular body  82  is formed, the mounting/attachment apparatus  146  becomes a molded-in insert during molding of the tubular body  82  which is bonded directly to the matrix composition  110  during molding. Alternatively, adhesive bonding the mounting/attachment apparatus  146  to the tubular body  82  of the handguard  80  may be accomplished using the matrix composition  110  as a coating which is applied to the tubular body  82  after molding, which may be brushed on. The mounting/attachment apparatus  146  may then be placed in overlying relationship to the coating and held with pressure thereto until the matrix composition  110  has suitably cured. 
     The mounting/attachment apparatus  146  may comprise a one-piece tubular mounting member  151  with a longitudinal passage  150  having an inner profile  156  (sides/surfaces) which includes a plurality of longitudinally oriented, semi-circular ribs  154 . The ribs  154  may be spaced such that a longitudinally oriented groove  158  is formed between each pair of adjacent ribs  154 . As shown, the ribs  154  and grooves  158  may extend longitudinally, and more particularly substantially parallel (e.g. plus or minus 5 degrees) to a longitudinal axis  160  of the mounting/attachment apparatus  146 , which may be the same as the longitudinal axis LA of the handguard  80 . 
     The ribs  154  may extend continuously for the full (longitudinal) length of the mounting/attachment apparatus  146 . However, in some embodiments, a circular (transverse) raceway  162  may circumscribe the inner profile  156  of the mounting/attachment apparatus  146 . The raceway  162  may be understood to be located between adjacent rib segments, and, as such, cause the ribs  154  to extend non-continuously along the inner profile  156  of the mounting/attachment apparatus  146 . 
       FIG. 10  shows the configuration of a conventional barrel nut  163  that, in operation, couples to the firearm  10 . The barrel nut  163  comprises a main cylindrical (annular) internally threaded body portion  164 , and an outwardly protruding (transverse), circular, scalloped lip/flange  165  having a plurality of equally sized and spaced tines  166  extending radially and circumferentially around the cylindrical body  164 . The tines  166  are substantially perpendicular to a longitudinal axis  170  of the barrel nut  163 , which may be the same as the longitudinal axis LA of the handguard  80 . The tines  166  are spaced such that a plurality of equally sized and spaced scalloped regions  172  are formed between adjacent tines  166 . 
     The shape of the inner profile  156  of the mounting/attachment apparatus  146  corresponds to the shape of the outer profile of the scalloped lip/flange  165  of the barrel nut  163  to allow the inner profile  156  of the mounting/attachment apparatus  146  to slideably engage the profile of the scalloped lip/flange  165  of the barrel nut  163 . 
     More specifically, the grooves  158  of the mounting/attachment apparatus  146  slideably engage with the tines  166  of the barrel nut  163 , while the ribs  154  of the mounting/attachment apparatus  146  slideably engage with the scalloped regions  172  of the barrel nut  163 . When the mounting/attachment apparatus  146  slideably engages with the barrel nut  163  along the longitudinal axis  160 / 170 , the barrel nut  163  inhibits the mounting/attachment apparatus  146  from rotating about longitudinal axis  160 / 170 . However, in embodiments including the raceway  162 , when the tines  166  of the barrel nut  163  enter the raceway  162  the mounting/attachment apparatus  146  may be rotated about longitudinal axis  160 / 170 . 
     For example, the mounting/attachment apparatus  146  may be rotated as necessary for the tines  166  align with the ribs  154 , which will prevent longitudinal movement of the mounting/attachment apparatus  146 /handguard  80  along longitudinal axis  160 / 170 , as well as align mounting apertures  81  ( FIG. 1 ) of the handguard  80  with mounting (threaded) apertures  153  ( FIG. 9 ) of the mounting/attachment apparatus  146 . 
     Thereafter mounting and attachment of the handguard  80  may be completed by inserting a mechanical (threaded) fastener  85  ( FIG. 1 ) through an aperture  81  in the handguard  80  which aligns with one of the mounting apertures  153  ( FIG. 9 ) in the mounting/attachment apparatus  146 , and threading the mechanical (threaded) fastener  85  into threaded mounting aperture  153 . 
     In some embodiments, a mounting/attachment apparatus according to the present disclosure may be coupled to firearm  10  prior to coupling the handguard  80  to firearm  10 . For example referring now to  FIG. 11 , there is shown a mounting/attachment apparatus  174  which may be coupled to firearm  10  prior to coupling the handguard  80  to firearm  10 . 
     As shown in  FIGS. 11-13 , mounting/attachment apparatus  174  may comprise at least one member or may be comprised of two or more members. For example, the mounting/attachment apparatus  174  may include a first mounting member  176  and a second mounting member  177 . The first mounting member  176  and the second mounting member  177  may have different shapes and/or sizes. However, as shown with the present embodiment, the first mounting member  176  may be the same shape as to match (or be identical to) the second mounting member  177  in size and shape. Furthermore, any general discussion of the mounting/attachment apparatus  174  will encompass all embodiments of the mounting/attachment apparatus  174  including those embodiments having at least the first mounting member  176  and the second mounting member  177 . 
     In operation, mounting members  176 ,  177  form a collar  178  (see  FIGS. 14 and 15 ) which surrounds (overlies) the barrel nut  163 . More particularly, mounting members  176 ,  177  each comprise a first, or collar, region  179 , which surrounds (overlies) the cylindrical body portion  164  of barrel nut  163 , as well as a rearward portion of the scalloped lip/flange  165 , including the tines  166 . First (collar) region includes an inner profile/side  180  and an outer profile/side  183 . The inner profile/side  180  and the outer profile/side  183  may take the same or different shapes (e.g., cylindrical, square, hexagonal, octagonal, etc. . . . ). For example, As shown the inner profile/side  180  may comprise a cylindrically shaped surface  181  and the outer profile/side  183  may have a plurality of adjacent planar surfaces  184 , arranged at an acute angle relative to one another, which together may form a polygon such as an octagon. 
     More particularly, the shape of the surfaces of the inner profile/side  180  of first (collar) region of mounting members  176 ,  177  may engage, and mate with, the shape of the surface of the underlying outer profile of the barrel nut  163 , while the shape of the surfaces of the outer profile/side  183  of first (collar) region of mounting members  176 ,  177  may engage, and mate with, the shape of the surfaces of the overlying inner profile  89  of the handguard  80 . 
     As shown, for example, in order to engage and mate with the barrel nut  163  shown in  FIG. 10 , the inner profile/side  180  of first (collar) region  179  of mounting members  176 ,  177  may provide a cylindrical surface  181  which engages and mates with an underlying cylindrical surface  168  of cylindrical body portion  164  of barrel nut  163 , as well as a leading (forward) conical surface  182  which engages and mates with an underlying conical rear surface  167  of scalloped lip/flange  165 , including tines  166 . Similarly, in order to engage, and mate with, the handguard  80  shown in  FIG. 4 , the outer profile/side  183  of first (collar) region of mounting members  176 ,  177  provide a plurality of planar surfaces  184  which together may form a polygon such as an octagon which engages and mates with octagonal profile  89  of tubular body  82  of handguard  80 . 
     In addition to the foregoing, the mounting/attachment apparatus  174 , and more particularly each of mounting members  176 ,  177 , may include at least one threaded mounting aperture  186  (similar to aperture  153 ) in the first (collar) region  179  to receive mechanical (threaded) fastener  85  therein to retain and fasten the handguard  80  to the mounting/attachment apparatus  174  when assembled. The mounting aperture  186  may be a through-hole which extends completely through the first (collar) region  179 , or a blind-hole which extends partially through the first (collar) region  179 . In other embodiments, mounting aperture  186  may extend completely through the first (collar) region  179  and not be threaded. Mounting aperture  186  may then be aligned with a threaded aperture in the barrel nut  163  to receive the mechanical (threaded) fastener  85 . 
     Continuing with  FIGS. 12 and 13 , the mounting/attachment apparatus  174 , and more particularly each of mounting members  176 ,  177 , may comprise a second, or tab, region  185  which projects longitudinally from first (collar) region  179  along the longitudinal axis  160 . The second (tab) region  185  has a shape that corresponds to (or fits within) the scalloped regions  172  of the barrel nut  163 . When the tab  185  of the mounting/attachment apparatus  174  engages at least one of the scalloped regions  172 , the rotation of the mounting/attachment apparatus  174  about the longitudinal axis  170  of the barrel nut  163  is inhibited due to a positive mechanical interference. In such regard, second region  185  may be understood to provide a locking (anti-rotation) tab  185  which inhibits rotation of the mounting members  176 ,  177  relative to the barrel nut  163 . 
     Referring now to  FIGS. 14 and 15 , mounting members  176 ,  177  of mounting/attachment apparatus  174  are shown seated (coupled) to the barrel nut  163 . As shown, mounting members  176 ,  177  form a multi-piece (two-piece) collar  178  which at least partially circumscribes (encircles) and overlies the barrel nut  163 . More particularly, the inner profile/side  180  of first (collar) region  179  of mounting members  176 ,  177  provides a cylindrical surface  181  which engages and mates with underlying cylindrical surface  168  of cylindrical body portion  164  of barrel nut  163 , as well as a conical surface  182  which engages and mates with an underlying conical rear surface  167  of scalloped lip/flange  165 , including tines  166 . Also as shown, the first (collar) region  179  of the mounting/attachment apparatus  174  extends longitudinal to the longitudinal axis  170  of the barrel nut  163 , and is substantially equal in longitudinal length to a longitudinal length of the cylindrical body portion  164  of barrel nut  163 . In this manner, the conical surface  182  of mounting members  176 ,  177 , as well as a leading (forward) end  190  of mounting members  176 ,  177 , may engage (contact) at least one of the tines  166  of the barrel nut  163 , while the trailing (rear) end  192  of mounting members  176 ,  177  may engage (contact) against upper receiver  16  to inhibit longitudinal (axial) movement of the of mounting members  176 ,  177 . To prevent rotational movement around the longitudinal axis  170  of the barrel nut  163 , the second (tab) region  185  of the mounting/attachment apparatus  174  engages in one of the scalloped regions  172 . 
     In embodiments where the mounting/attachment apparatus  174  partially circumscribes the collar  178 , the mounting/attachment apparatus  174  may be positioned and arranged to provide combustion gas return tube passageway  193 , particularly between the mounting members  176 ,  177  to receive combustion gas return tube  42  ( FIG. 4 ) therein and the combustion gas return tube  42  may be coupled to combustion gas return tube inlet  194 . The passageway  193  is further aligned with at least one of the scalloped regions  172  of the barrel nut  163  such that the combustion gas return tube  42  may be received in one of the scalloped regions  172  as well as passageway  193 . While the passageway  193  is shown as being located between separate mounting members  176 ,  177 , the passageway  193  may also be formed by a notch formed in one or both of the mounting members  176 ,  177  and extending longitudinally along the complete length of the mounting members  176 ,  177 . In embodiments where the passageway  193  is provided between mounting members  176 ,  177 , the first mounting member  176  and the second mounting member  177  may circumscribe only those portions of the collar  178  where the gas return tube  42  does not pass. 
     As shown in  FIG. 16 , the handguard  80  slideably engages the outer profile/side  183  of the mounting/attachment apparatus  174 . When the outer profile/side  183  of the mounting/attachment apparatus  174  takes a non-cylindrical (e.g. polygonal shape shown as an octagonal shape) which substantially conforms or matches to the inner profile  89  of the handguard  80 , the handguard  80  is restrained from rotating about the longitudinal axis  170  of the barrel nut  163 . As shown, in order for the handguard  80  to slideably engage with the mounting/attachment apparatus  174 , the handguard  80  and the mounting/attachment apparatus  174  may both have a octagonal shape wherein the cross-sectional area enclosed by the handguard  80  is equal to or larger than the mounting/attachment apparatus  174 , permitting the handguard  80  to slideably engage the mounting/attachment apparatus  174  while optionally forming an interference coupling. Alternatively, the cross-sectional area enclosed by the handguard  80  may be less than the mounting/attachment apparatus  174  to form an interference fit, however such may require additional force for the handguard to slideably engage with the mounting/attachment apparatus  174 . 
     As shown in  FIG. 17 , when the handguard  80  fully engages the mounting/attachment apparatus  174 , the mounting aperture  81  of the handguard  80  is substantially concentric with the threaded mounting aperture  186  of the mounting/attachment apparatus  174 . As such, a mechanical (threaded) fastener  85  (e.g., bolt or screw) may be inserted through mounting aperture  81  of the handguard  80  and threadably engaged in the threaded mounting aperture  186  of the mounting/attachment apparatus  174 , mechanically coupling the handguard  80  to the mounting/attachment apparatus  174 . In some embodiments, the mounting aperture  81  of handguard  80  may be countersunk (or counter-bored) such that the mechanical (threaded) fastener  85  is substantially flush with the handguard  80  when fully engaged. 
     When the handguard  80  is coupled to the mounting/attachment apparatus  174  in the above manner, the handguard  80  is inhibited from rotating around the longitudinal axis LA and moving longitudinally along the longitudinal axis LA. As may be appreciated, rotational movement of the handguard  80  is inhibited by mechanically coupling/engaging handguard  80  to mounting members  176 ,  177  of mounting/attachment apparatus  174  via one or more threaded fasteners  85  and/or the shape of the outer profile/side  183  of the mounting/attachment apparatus  174  corresponding to the profile  89  of the handguard  80 , and mechanically coupling/engaging one or more tab region  185  of mounting members  176 ,  177  of mounting/attachment apparatus  174  in scalloped regions  172  of the barrel nut  163 . As also may be appreciated, forward longitudinal movement of the handguard  80  is inhibited by mechanically coupling/engaging handguard  80  to mounting members  176 ,  177  of mounting/attachment apparatus  174  via one or more threaded fasteners  85 , and the collar region  179  of mounting members  176 ,  177  of mounting/attachment apparatus  174  being restrained against forward longitudinal movement by scalloped lip/flange  165  of barrel nut  163 . As also may be appreciated, rearward longitudinal movement of the handguard  80  is inhibited by mechanically coupling/engaging handguard  80  to mounting members  176 ,  177  of mounting/attachment apparatus  174  via one or more threaded fasteners  85 , and the collar region  179  of mounting members  176 ,  177  of mounting/attachment apparatus  174  being restrained against rearward longitudinal movement by receiver  16 . 
     As shown by the drawings herein, to add stability to the mounting of the handguard  80  to the mounting/attachment apparatus  174 , as well as the mounting/attachment apparatus  174  to the barrel nut  163 , the collar  178  may be configured to overlie at least 50% of the surface area of the outer surface  168  of the cylindrical body portion  164  of the barrel nut  163 , and more particularly, at least 60%, 70%, 80%, 80% or 85% of the surface area of the outer surface  168  of the cylindrical body portion  164  of the barrel nut  163 . 
     Similarly, the collar  178  may be configured to overlie at least 50% of the overall longitudinal length of the cylindrical body portion  164  of the barrel nut  163 , and more particularly, at least 60%, 70%, 80%, 90% or 95% of the overall longitudinal length of the cylindrical body portion  164  of the barrel nut  163 . 
     Similarly, the collar  178  may be configured to overlie at least 50% of the overall circumferential length of the cylindrical body portion  164  of the barrel nut  163 , and more particularly at least 60%, 70%, 80% or 85% of the overall circumferential length (circumference) of the cylindrical body portion  164  of the barrel nut  163 . In order to provide combustion gas return tube passageway  193  to accommodate combustion gas return tube  42 , the collar  178  may be configured to overlie less than the overall circumferential length of the cylindrical body portion  164  of the barrel nut  163 , and more particularly less than 90-95% of the overall circumferential length (circumference) of the cylindrical body portion  164  of the barrel nut  163 , with the remaining 5-10% (of greater) of the circumferential length the cylindrical body portion  164  of the barrel nut  163  being used to provide combustion gas return tube passageway  193  to accommodate combustion gas return tube  42 . Thus, the collar  178  may be configured to overlie 50% to 95% of the overall circumferential length of the cylindrical body portion  164  of the barrel nut  163 , or any other combination of percentages above (e.g. 50%-90%, 60%-95%, 60%-90%, etc.) 
     As the longitudinal length and the circumferential length of the collar  178  increase, and the corresponding surface area, such may provide the mounting/attachment apparatus  174  with greater stability for mounting and attaching the handguard  80 . 
     Referring now to  FIG. 18 , there is shown another embodiment of a handguard mounting/attachment apparatus according to the present disclosure, which may comprise first and second mounting members  176 ,  177  having an outer profile/side  183  which has an arcuate surface  184 . As shown, the arcuate surface  184  of each outer profile/side  183  of each of first and second mounting members  176 ,  177  may be semi-cylindrical, and more particularly formed by an arc of constant radius over a range of 120 to 170 degrees. 
     While embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present invention. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified, unless clearly indicated to the contrary. 
     LISTING OF REFERENCE CHARACTERS 
     
         
           10  firearm 
           12  receiver 
           14  lower receiver 
           16  upper receiver 
           18  magazine receptacle 
           30  bolt carrier 
           40  barrel 
           42  combustion gas return tube 
           50  butt stock 
           60  pistol grip 
           80  handguard 
           81  mounting aperture 
           82  tubular body 
           83  wall of tubular body 
           84  center passage 
           85  mechanical (threaded) fastener 
           86  tubular body outer surface 
           88  tubular body inner surface 
           89  inner profile 
           90  apertures 
           92  top side of handguard 
           94  accessory rail 
           96  rail ribs 
           98  rail slots 
           100  rail reinforcement structure 
           102  reinforcement layer 
           104  reinforcement layer 
           106  reinforcement layer 
           108  reinforcement layer 
           110  matrix composition 
           120  lower elongated rail segment 
           122  planar upper surface 
           130  upper elongated rail segment 
           132  planar lower surface 
           140  inner elongated rail segment 
           146  mounting/attachment apparatus 
           150  longitudinal passage 
           151  tubular mounting member 
           152  outer profile of mounting/attachment apparatus 
           153  mounting aperture of mounting/attachment apparatus 
           154  ribs of mounting/attachment apparatus 
           156  inner profile of mounting/attachment apparatus 
           158  grooves of mounting/attachment apparatus 
           160  longitudinal axis of mounting/attachment apparatus 
           162  raceway of mounting/attachment apparatus 
           163  barrel nut 
           164  main (cylindrical) body portion of barrel nut 
           165  flange/lip of barrel nut 
           166  tines of barrel nut 
           167  outer conical surface of barrel nut 
           168  outer cylindrical surface of barrel nut 
           170  longitudinal axis of barrel nut 
           172  scalloped regions of barrel nut 
           174  mounting/attachment apparatus 
           176  first mounting member 
           177  second mounting member 
           178  collar 
           179  first (collar) region of mounting/attachment apparatus 
           180  inner profile/side of mounting/attachment apparatus 
           181  surface of inner profile/side of first (collar) region 
           182  conical surface of inner profile/side of first (collar) region 
           183  outer profile/side of mounting/attachment apparatus 
           184  surface of outer profile/side of first (collar) region 
           185  second (tab) region of mounting/attachment apparatus 
           186  mounting aperture of mounting/attachment apparatus 
           190  leading (forward) end of mounting/attachment apparatus 
           192  trailing (rear) end of mounting/attachment apparatus 
           193  passageway 
           194  combustion gas return tube inlet 
         LA longitudinal axis