Patent Publication Number: US-8522467-B1

Title: Composite hand guard with integral rail

Description:
PRIORITY CLAIM(S) 
     Priority of U.S. Provisional Patent Application Ser. No. 61/380,644, filed on Sep. 7, 2010, is claimed; and is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to hand guards and accessory rails for firearms. 
     2. Related Art 
     Various accessories can be mounted to a firearm, such as an M-16, AR-15, AR-10 or M4 type rifle, using a rail, such as a Picatinny rail system. For example, see U.S. Pat. No. 7,716,865; 7,430,829; 7,685,758 or 2008-0092422. The rail is usually mounted to some portion of the firearm, such as an upper receiver. 
     SUMMARY OF THE INVENTION 
     It has been recognized that it would be advantageous to develop a hand guard with an integrated rail that is strong, light-weight and stiff. 
     The invention provides a firearm accessory device in combination with a firearm having a barrel. An elongated tube extends axially along at least a portion of a length of the barrel and extends circumferentially around the barrel. A hand guard is formed by the tube around a bottom and lateral sides of the tube at a proximal end of the tube. An elongated rail is formed by the tube along a top of the tube, a bottom of the tube at a distal end of the tube, a lateral side of the tube at the distal end of the tube, or combinations thereof. The elongated rail is aligned with the shell wall and the barrel, and has a cross-sectional shape orthogonal to the shell wall and the barrel with a narrower neck and a wider head, with the enlarged head being segmented along a length thereof. A monolithic shell wall forms the tube and extends circumferentially around the barrel, and forms the hand guard and the elongated rail, with the shell wall substantially surrounding the barrel in a spaced-apart relationship. An elongated hollow is defined between the barrel and the shell wall, and extends continuously and uninterrupted radially between the barrel and the shell wall, and into the narrower neck of the rail. 
     In addition, the invention provides a firearm accessory device in combination with a firearm having a barrel. A hand guard is disposed around at least a portion of the barrel and has an elongate shell with an axis aligned with an axis of the barrel. The shell has a shell wall spaced-apart from and circumscribing the barrel. An elongated rail protrudes from the shell and is defined by the shell wall. The rail has an axis aligned with an axis of the shell and the barrel. The rail has a cross-sectional shape orthogonal to the axis with a narrower neck a wider head coupled to the shell by the neck. An elongate hollow is defined by the shell wall with the hollow extending longitudinally between the barrel and the shell wall, and radially between the barrel and the shell wall and into the neck of the rail. 
     Furthermore, the invention provides a firearm accessory device with an elongated shell having a shell wall adapted to be spaced-apart from and circumscribing a barrel of a firearm and having a longitudinal axis aligned with a longitudinal axis of the barrel. The shell has a portion adapted to be griped by a user and defining a hand guard. The shell wall has another portion protruding radially away from the barrel defining an elongated rail. The rail has an axis aligned with an axis of the barrel. The rail has a cross-sectional shape orthogonal to the axis with a narrower neck a wider head coupled to the shell by the neck. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention; and, wherein: 
         FIG. 1  is a side view of an integrated hand guard and accessory rail for a firearm in accordance with an embodiment of the present invention; 
         FIG. 2  is a cross-sectional end view of the hand guard and accessory rail of  FIG. 1 , taken along line  2  of  FIG. 1 ; 
         FIG. 3  is an end view of the hand guard and accessory rail of  FIG. 1 ; 
         FIG. 4  is a top view of the hand guard and accessory rail of  FIG. 1 ; 
         FIG. 5  is a cross-sectional side view of the hand guard and accessory rail of  FIG. 1 , taken along line  5  of  FIG. 3 ; 
         FIG. 6  is a side view of the firearm with the hand guard and accessory rail of  FIG. 1 ; 
         FIG. 7  is a cross-sectional end view of the hand guard and accessory rail of  FIG. 1 , taken along line  7  of  FIG. 6 ; 
         FIG. 8  is a cross-sectional end view of the hand guard and accessory rail of  FIG. 1 , taken along line  8  of  FIG. 6 ; 
         FIG. 9  is a side view of another integrated hand guard and accessory rail for a firearm in accordance with another embodiment of the present invention; 
         FIG. 10  is a cross-sectional end view of the hand guard and accessory rail of  FIG. 9 , taken along line  10  of  FIG. 9 ; 
         FIG. 11  is an end view of the hand guard and accessory rail of  FIG. 9 . 
     
    
    
     Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. 
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT(S) 
     As illustrated in the  FIGS. 1-8 , an integrated hand guard and accessory rail device, or firearm accessory, indicated generally at  10 , in an example implementation in accordance with the invention is shown that can be disposed over a barrel of a firearm  12  ( FIG. 6 ), and/or can be or can form part of an upper receiver of a firearm. The firearm can be an M-16, AR-15, AR-10 or M4 type rifle, or the like. The integrated hand guard and accessory rail  10 , or firearm accessory, has a hand guard  14  or hand guard portion, and that has at least one integrated accessory rail  16   a  or  16   b , such as a Picatinny rail or the like. The accessory rail  16  can receive one or more accessories, represented by  18   a  and  18   b  ( FIGS. 6-8 ), detachably coupled to the rail  16  and thus the firearm  12 , including, for example, a hand grip with an axis transverse to the longitudinal axis of the barrel; a light source; a laser; a scope; a tactical scope; a sight; a night vision system; a bipod; a stand; a rail cover; a carrier or mount; a stock; a retractable stock; a foregrip; a sling; a sling mount or adaptor; a magazine pouch; a bayonet; a bayonet mount; a clamp or fixture or combinations thereof. Integrating the hand guard and rail can provide a stiff rail and hand guard to resist relative movement of the accessory, such as a site, to help maintain accuracy of the firearm. The integrated hand guard and accessory rail  10 , or firearm accessory, includes an elongated tube  4  extending axially along at least a portion of a length of a the barrel  20  ( FIGS. 6-8 ), and extending circumferentially around the barrel. The tube substantially surrounds the barrel in a spaced-apart relationship, and with an annular air space therebetween. The tube  4  includes a monolithic shell wall  8  forming the tube, the hand guard  14  and the accessory rail  16   a  and/or  16   b . Thus, the shell wall  8  extends circumferentially around the barrel  20  and surrounds the barrel in a spaced-apart relationship, or is spaced-apart therefrom. 
     The hand guard  14  is disposed around at least a portion of the barrel  20  ( FIGS. 6-8 ) to allow the user to grasp the hand guard at the barrel, without touching the barrel, and thus protecting the user&#39;s hand from the heat of the barrel (which can reach approximately 500° F.). The hand guard  14  can have a longitudinal axis parallel with a longitudinal axis of the barrel of the firearm. The hand guard is formed by the tube around a bottom and lateral sides of the tube at a proximal end of the tube or device. The hand guard can have a bottom with a convex curvature that is substantially round or circular cross-section. In addition, the hand guard can include lateral sides extending from the bottom that are substantially straight and vertical. The top of the hand guard, tube or shell wall can include at least a portion with a convex curvature that is round or circular cross-section, with a radius of the bottom being greater than the top to create a broader bottom surface to be grasped by a user. Straight vertical lateral sections can interconnect the circular top and bottom of the hand guard at lateral sides thereof. A plurality of longitudinally spaced-apart ridges  22  is disposed on the outer surface of the bottom of the hand guard  22  at a proximal end or rear end or portion of the hand guard or device. The ridges are oriented transverse to the longitudinal axis and spaced-apart to receive a user&#39;s fingers therebetween to facilitate grasping of the firearm. Thus, the bottom of the hand guard  14  can lay in palm and/or fingers of the user&#39;s hand during use, and separates the user&#39;s hand from the barrel  20 . 
     The accessory rail can include an upper rail  16   a  disposed on the top of the hand guard or device, and a lower rail  14   b  disposed on a bottom of the hand guard. The upper rail  16   a  can be formed along the top of the tube, while the bottom rail  16   b  can be formed along a bottom of the tube at a distal end of the tube. (One or more lateral rails  16   c  can be formed along one or more lateral sides of the tube and at the distal end of the tube, as shown in  FIGS. 9-11 .) The rails can be aligned with the tube, shell wall, barrel and longitudinal axis. The upper and lower rails  16   a  and  16   b  can be integrally formed and monolithic with the hand guard  14  and the device can have a monolithic shell wall that is continuous, uninterrupted and seamless (except for vent holes and/or mounting holes) around the circumference thereof to provide stiffness and accuracy. In addition, rails can be disposed on the side of the hand guard, such as by attachment with mechanical fasteners to holes in the sides of the handguard. The lower rail  14   b  can be disposed on a distal or forward portion of the hand guard, tube or device. The hand guard  14  can be formed along a first longitudinal portion or proximal end, and the bottom rail  16   b  can be formed along a second longitudinal portion or distal end. The upper rail  16   a  can extend the length of the hand guard or device. In addition, the upper rail  16   a  can align with an accessory rail of an upper receiver of the firearm, as shown in  FIG. 6 . The rails  16   a  and  16   b  can have a narrower neck  26  extending from the hand guard or tube, with an enlarged head  30  thereon so that the head is spaced from the hand guard or tube and connected thereto by the neck. The rails have a longitudinal axis aligned with the axis of the barrel. The head is segmented along a length thereof to form a series of spaced-apart grooves  34  transverse or orthogonal to the longitudinal axis. The head  30  and neck  26  of the rails are received within a groove  36  of the accessory  18   a  and/or  18   b , while a locking pin  40  of the accessory is received in one of the grooves  34  to resist movement of the accessory along the rail, as shown in  FIGS. 7 and 8 . 
     The hand guard  14  and accessory rail  16   a  and/or  16   b  are separate and distinct structures with different shapes, sizes, and/or profiles. The hand guard is shaped with broad curvatures and smooth surfaces to be grasped by a user, while the accessory rail is shaped and sized to releasably and lockably receive an accessory. The hand guard  14  can be free of the accessory rail  16   a  and  16   b , or without the accessory rail interfering with the grip formed by the hand guard. 
     The hand guard  14  and/or rail  16   a  and  16   b  are formed by the elongate tube  4  with a longitudinal axis aligned with the axis of the barrel  20 . The tube  4  has shell wall  8  spaced-apart from and circumscribing the barrel  20 . The shell wall  8  defines and forms the hand guard  14  and rail  16   a  and  16   b . The rail can protrude from the tube or profile of the tube. The tube  4  and shell wall  8  define an elongate annular hollow  44  ( FIGS. 7 and 8 ) extending longitudinally between the barrel  20  and shell wall  8 , and radially between the barrel  20  and shell wall  8 . Without the barrel, the tube and shell wall can define a central hollow  46  ( FIGS. 2 and 3 ). The hollow  44  or  46  extends into the neck  26  of the rail. Thus, the neck  26  of the rail can be hollow. The hollow neck  26  can form a channel or channel hollow  48 . Thus, the elongate hollow comprises a main central hollow  44  or  46  and a channel  48  connected thereto and defined by the rail. The hollow extends from the barrel continuously and uninterrupted therefrom through the annular hollow  44  and into the channel  48 . The shell wall  8  circumscribes the barrel forming the monolithic, continuous, uninterrupted and seamless wall forming both the hand guard  14  and the rail  16   a  and  16   b  in a single revolution around the barrel. The hand guard and rail can be a monolithic structure with the shell wall being continuous and uninterrupted and seamless as it circumscribes the axis. The channel walls can be substantially orthogonal to the curved walls of the top and bottom. The bottom of the channel can be concave or arcuate. Thus, the wall circumscribing the barrel can have a substantially constant thickness around substantially the entire barrel forming the hand guard (or top and bottom curved portions and lateral portions), without increases in thickness to accommodate fasteners. The rail or head can be thicker than the hand guard. The cross-sectional shape of the rail interrupts the curvature of the top and bottom of the tube or shell wall and adds elongated hollow lobes to the annular hollow of the hand guard. 
     The shell wall can be formed by a composite material with a fiber, such as carbon, in a resin matrix. The shell wall can have a non-uniform thickness extending circumferentially or radially at the rail. The fiber can include various layers of woven mat. For example, a majority of the wall can be formed by eight layers, including inner and outermost layers with fibers oriented at 0 and 90 degrees with respect to the longitudinal axis (or longitudinally and laterally or circumferentially); four intermediate layers of fiber oriented at 45 degrees with respect to the longitudinal axis (or helically in both directions); and two interior layers of unidirectional fibers oriented longitudinally or at 0 degrees. In addition, additional unidirectional, longitudinal fibers, indicated at  50 , can be disposed in the rail or head of the rail. The additional unidirectional, longitudinal fibers in the rail can help maintain the stiffness of the rail and hand guard, and can resist relative movement of accessories mounted to the rail. Thus, the fiber density of the wall increases at the rails with respect to the hand guard. The rail can have between 50-80% more unidirectional fibers in one aspect, or 60-70% more unidirectional fibers in another aspect. Such a lay-up can provide a good coefficient of thermal expansion (CTE). 
     The hand guard can be provided with end caps  60  ( FIG. 6 ) bonded and/or mechanically fastened to the open ends of the tube to couple the tube to the barrel or the upper receiver. The end caps can also be formed of composite material, or can be plastic or metal, such as aluminum. 
     The hand guard described above provides a combined rail and hand guard that is strong, light-weight and stiff. 
     Referring to  FIGS. 9-11 , another integrated hand guard and accessory rail device  10   b , or firearm accessory, is shown that is similar to that described above, and which description is herein incorporated by reference. The device  10   b  can have one or more side rails  16   c  integrally formed by the shell wall with the tube as described above. 
     It will be appreciated that the integrated hand guard and accessory rail devices, or firearm accessories, described above can be provides with a single rail, such as only an upper, bottom, or side rail. 
     The tube or shell wall can have one or more vent holes or apertures  60  extending therethrough. The vent holes or apertures  60  can be located in the lateral side walls. Additional apertures can be formed in the tube or shell wall to accommodate fasteners. For example, separate side rails can be coupled to the side walls of the tube or shell using fasteners. 
     A method for making the integrated hand guard and accessory rail, or firearm accessory, for a firearm as described above includes obtaining or using an internal mandrel and an external mold. The external mold can have a cavity shaped as an exterior of a hand guard with at least one rail. The external mold can have at least two halves to open and close about the internal mandrel. The internal mandrel can be disposable within the cavity. Thus, an annular cavity is defined between the internal mandrel and external mold to receive fiber and resin. Fiber, such as woven mat fiber and/or unidirectional fiber, is layed-up on the internal mandrel, and inside the cavity of the external mold. The fiber can be pre-preg fiber pre-impregnated with resin. Additional longitudinal fibers can be layed-up in the cavity defining the at least one rail. For example, a woven mat fiber can be layed-up on the internal mandrel and oriented at 0 and 90 degrees. Similarly, a woven mate fiver can be layed-up in the cavity of the external mold and oriented at 0 and 90 degrees. One or more additional woven mat layers can be layed-up on the internal mandrel and oriented at 45 degrees. Similarly, one or more additional woven mat layers can be layed-up in the cavity of the external mold and oriented at 45 degrees. One or more unidirectional mats can be layed-up on the mandrel and/or in the cavity and oriented at 0 degrees. The external mold is closed about the internal mandrel with the fiber therebetween. The mold can be sealed about the internal mandrel. Resin can be injected into the cavity between the internal mandrel and the external mold under pressure. The mold can be opened and the fiber with the resin removed from the external mold and internal mandrel. The resin can cure in and/or out of the mold. Grooves can be cut in a head of the at least one rail, with the grooves oriented transverse to a longitudinal axis of the rail. Other holes for venting or mounting can be cut unto the hand guard. 
     As used herein, cross-sections are taken orthogonal or perpendicularly to the axis. 
     While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.