Abstract:
A novel firearm handguard system includes a handguard and an integrated gas tube. In a particular embodiment, the gas tube includes fastening feature and the handguard includes a complementary fastening feature that is adapted to be coupled to the fastening feature of the gas tube. In a more particular embodiment, the gas tube includes an integral mounting rail and the handguard includes an integral mounting rail. In an even more particular embodiment, the gas tube and the handguard each include a feature for configuring removable rail systems thereon.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of copending U.S. Provisional Patent Application No. 61/461,088, filed Jan. 13, 2011 by the same inventor, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to firearms, and more particularly to gas operated rifles. Even more particularly, the invention relates to a rifle handguard system having an integral gas tube. 
         [0004]    2. Description of the Background Art 
         [0005]    For several decades, AK (Avtomat Kalashnikov) type rifles such as the AK-47 have remained the most widely used assault rifles. These rifles are well known for their reliability, simple operation, and manufacturability. However, they were not originally designed with the intent to support optics and/or other tactical accessories such as, for example, rail mounted flashlights, laser sights, etc. However, their use has since become much more widespread and it is often desirable to mount optics and other accessories on the rifle. 
         [0006]    Several systems for mounting optics and/or other tactical accessories on gas operated rifles (e.g., AK style rifles) have been developed. Typically, such systems include an upper handguard and lower handguard that replace the existing original equipment manufacturer (OEM) upper and lower handguards, respectively. In such systems, the replacement upper handguard and/or replacement lower handguard typically incorporates some type of rail system such as, for example, picatinny rails, weaver rails, etc. 
         [0007]    Replacing the OEM handguard system in, for example, an AK-47 typically involves first rotating a gas tube locking lever located on the sight block so that the rear end of the gas tube can be lifted out from a gas tube receiving socket located on the fore-end of the sight block. Once the rear end of the gas tube is free, the fore-end is then disconnected from the gas block by pulling the handguard/gas tube assembly away from the gas block. Once the upper handguard/gas tube assembly is free, the OEM upper handguard has to be separated from the OEM gas tube. This requires securing the gas tube in place while the upper handguard is rotated 180 degrees about the gas tube. Once rotated, the upper handguard can be pulled away from the gas tube. Then the replacement upper handguard is mounted on the OEM gas tube in the reverse order of that which the OEM upper handguard was removed. Before mounting the replacement upper handguard/OEM gas tube assembly back on the rifle, the OEM lower handguard is removed from the rifle by first releasing the handguard retainer lever so that the retainer is free to move along the rifle&#39;s barrel. Once the retainer is free to move, the OEM lower handguard can be pulled away from the receiver. Then, the replacement lower handguard is mounted to the rifle in the reverse order of that which the OEM lower handguard was removed. Finally, the replacement upper handguard/OEM gas tube assembly is mounted to the rifle in the reverse order of that which the OEM upper handguard/OEM gas tube assembly was removed. 
         [0008]    Although such systems provide a means for mounting optics and other accessories on such rifles, there are drawbacks. For example, the OEM gas tube has to be used with the replacement handguard system, thus requiring the removal of the OEM gas tube from the OEM upper handguard. This removal process is well known to be a challenge and oftentimes requires cutting the OEM upper handguard to remove the OEM gas tube. 
         [0009]    Addressing the problems associated with having to harvest the OEM gas tube from the OEM upper handguard, many systems eliminate the upper handguard/gas tube assembly altogether. For example, some handguard systems employ replacement gas tubes that include rails. In these types of systems, the gas tube is secured to the top of the rifle barrel via rigid securing members (e.g., brackets, straps, clamps, etc.) that wrap around the outer perimeter of the barrel. For example, U.S. Pat. No. 6,381,895, issued to Keeney et al., discloses an AK-47 gas tube that includes an integral optic mount  10  and a set of barrel mounting members  30 . The optic mount  10  is an integral rail formed on top of the gas tube. The barrel mounting members  30  are essentially rigid U-shaped straps fastened to the bottom of the gas tube via a set of screws  39 . Mounting members  30  wrap around the barrel so as to secure the gas tube directly thereon. 
         [0010]    Although the system disclosed in U.S. Pat. No. 6,381,895 eliminates the challenges associated with having to harvest the OEM gas tube from the upper handguard, there are disadvantages to the design. For example, the system introduces additional components thus making field stripping the rifle for cleaning a very lengthy process. This is due at least to the requirement to disengage the clamps in order to remove the gas tube from the rifle. Another disadvantage is that lower handguards used with the system have to be unnecessarily bulky to provide the space occupied by the mounting members  30 . Yet another disadvantage is that the system requires a high number of parts. Yet another disadvantage is that the gas tube can reaches high temperatures because it is in direct contact with the barrel. 
         [0011]    What is needed, therefore, is a handguard system that facilitates simpler assembly and disassembly. What is also needed is a more compact handguard system. What is also needed is a handguard system that operates at a lower temperature. What is also needed is a handguard system with fewer parts. 
       SUMMARY 
       [0012]    The present invention overcomes the problems associated with the prior art by providing a firearm handguard system having handguard and an integral gas tube that mount together. 
         [0013]    The firearm handguard system includes a gas tube and a handguard. The gas tube includes a rear end adapted to engage a gas tube receiver socket of a firearm, a fore-end adapted to engage a gas block of the firearm, an interior surface defining a piston bore, an exterior surface, and a fastening feature. The handguard includes a rear end, a fore-end, an exterior surface, and a complementary fastening feature adapted to be coupled to the fastening feature of the gas tube. 
         [0014]    In a more particular embodiment, the fastening feature of the gas tube includes at least one aperture, the complementary fastening feature of the handguard includes at least one aperture, and at least one aperture of the fastening feature is aligned with one aperture of the complementary fastening feature. In a more particular embodiment, one of the fastening feature and the complementary fastening feature includes a threaded aperture and the other includes a clearance aperture. In an even more particular embodiment, the fastening feature of the gas tube includes at least one clearance aperture and at least one externally threaded fastener, the complementary fastening feature of the handguard includes an internally threaded aperture, and the external thread set and the internal thread set are adapted to mate with one another. In yet a more particular embodiment, the exterior surface of the gas tube and the exterior surface of the handguard are adapted to abut one another. 
         [0015]    In another particular embodiment, the fastening feature and the complementary fastening feature form a fixed mechanical joint directly between the gas tube and the hand guard. In a more particular embodiment, at least one of the fastening feature and the complementary fastening feature includes a threaded fastener that includes a first end secured directly to the gas tube and a second end secured directly to the handguard. 
         [0016]    In another particular embodiment, the exterior surface of the gas tube defines at least one planar side surface, the exterior surface of the handguard defines at least one planar side surface, and the planar side surface of the gas tube is coplanar to the planar side surface of the handguard. In a more particular embodiment, at least one of the side surface of the gas tube and the side surface of the handguard is adapted to receive a removable mounting platform. In an even more particular embodiment, the surface of the gas tube defines a plurality of threaded apertures adapted for configuring rail systems on the side surface of the gas tube. In another more particular embodiment, the side surface of the handguard defines a plurality of threaded apertures adapted for configuring rail systems on the side surface of the handguard. 
         [0017]    In an example embodiment, the exterior surface of the gas tube defines an integral rail system, and the exterior surface of the handguard defines another integral rail system. In the example embodiment, the gas tube is a first single body and the handguard is a second single body. 
         [0018]    Optionally, the handguard system further comprises a spring element seated within the handguard. The spring element has a first end and a second end. The first end is adapted to retain a cleaning rod disposed within the handguard, and the second end is adapted to exert a biasing force against the exterior surface of a firearm barrel. 
         [0019]    In an example embodiment, the gas tube is adapted to mount over a barrel and remain spaced apart from the barrel, and the handguard is adapted to mount under the barrel and remain spaced apart from the barrel. In this example embodiment, the gas tube and the handguard are adapted to be mounted on opposite sides of the barrel without contacting the barrel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements: 
           [0021]      FIG. 1  is a side view of a firearm handguard system mounted on a gas operated firearm; 
           [0022]      FIG. 2  is a rear perspective view of the handguard system of  FIG. 1  assembled; 
           [0023]      FIG. 3  is an exploded perspective view of the handguard system of  FIG. 1 ; 
           [0024]      FIG. 4  is a front perspective view of a gas tube of the handguard system of  FIG. 1 ; 
           [0025]      FIG. 5  is a top view of the gas tube of  FIG. 4 ; 
           [0026]      FIG. 6  is a cross-sectional view of the gas tube of  FIG. 5  taken along line A-A of  FIG. 5 ; 
           [0027]      FIG. 7  is a front perspective view of a handguard of the handguard system of  FIG. 1 ; 
           [0028]      FIG. 8  is a bottom view of the handguard of  FIG. 7 ; 
           [0029]      FIG. 9  is a top view of the handguard of  FIG. 7 ; 
           [0030]      FIG. 10  is a cross-sectional view of the handguard shown in  FIG. 7  taken along line B-B of  FIG. 8 ; 
           [0031]      FIG. 11  is a front perspective view of a spring clip of the handguard system of  FIG. 1 ; 
           [0032]      FIG. 12  is a front view of the handguard system of  FIG. 1 ; 
           [0033]      FIG. 13  is a perspective cross-sectional view of the handguard system of  FIG. 1 ; and 
           [0034]      FIG. 14  is a side cross-sectional view of the handguard system of  FIG. 1  taken along line C-C of  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    The present invention overcomes the problems associated with the prior art, by providing firearm handguard system that includes a gas tube and a lower handguard that are adapted to mount to one another. In the following description, numerous specific details are set forth (e.g., specific firearm models, rail types, materials, etc) in order to provide a thorough understanding of the invention. Those skilled in the art will recognize, however, that the invention may be practiced apart from these specific details. In other instances, details of well known metal manufacturing practices (e.g., machining, extrusion, etc.) and components have been omitted, so as not to unnecessarily obscure the present invention. 
         [0036]      FIG. 1  shows a side view of a firearm handguard system  100  mounted on a gas operated firearm  102  which is depicted by way of example as being an AK-47 assault rifle. 
         [0037]    Firearm  102  includes a receiver  104 , a barrel  106 , a gas block  108 , a rear site block  110 , a lower handguard retainer  112 , and a cleaning rod  114 . Receiver  104  provides the main structure that supports and houses the working components of firearm  102 . Barrel  106  extends from the fore-end  116  of receiver  104 . More specifically, the rear end of barrel  106  is mounted to a front trunnion (not visible) which is mounted in the fore-end of receiver  104 . Gas block  108  is fixed to barrel  106  and coupled to the fore-end of system  100 . Although not visible, gas block  108  includes in interior port that routes expanding combustion gasses from within barrel  106  to handguard system  100 . Rear site block  110  is mounted to barrel  106  and includes a gas tube receiver socket (not visible)  118  and a gas tube locking lever  120 . Socket  118  is located at the fore-end  122  of rear sight block  110  and is adapted to receive the rear end of a gas tube. Lever  120  provides a means for connecting/disconnecting a gas tube from rear sight block  110 . Lever  120  is shown in a locked position, wherein handguard system  100  is secured to rear sight block  110 . To release handguard system  100  from socket  118 , lever  120  is rotated to an unlocked position. Lower handguard retainer  112  is slidably coupled to barrel  106  and is adapted to receive the fore-end of a lower handguard. Retainer  112  includes a lever  124  that enables it to be locked to or unlocked from barrel  106 . When locked, lever  124  is positioned horizontally as shown and retainer  112  is secured to barrel  106 . To unlock retainer  112 , lever  124  is rotated clockwise until retainer  112  is free to move along barrel  106 . 
         [0038]      FIG. 2  shows a rear perspective view of handguard system  100  removed from firearm  102  and assembled. Handguard system  100  includes a gas tube  200  and a handguard  202 . 
         [0039]    Gas tube  200  includes a fastening feature  204 , a rear end  206 , a fore-end  208 , an exterior surface  210 , and an interior surface  212 . Fastening feature  204  facilitates the mounting of gas tube  200  to handguard  202 . Rear end  206  is adapted to engage gas tube receiver socket  118  of firearm  102 . Fore-end  208  is adapted to receive gas block  108 . Interior surface  212  defines a piston bore wherein the expanding combustion gasses from within barrel  106  are routed via gas block  108 . 
         [0040]    Handguard  202  includes a complementary fastening feature  214 , a rear end  216 , a fore-end  218 , and an exterior surface  220 . Complementary fastening feature  214  is adapted to be coupled to fastening feature  204  of gas tube  200 . Rear end  216  is adapted to engage the trunnion (not shown) at fore-end  116  of receiver  104 . Fore-end  218  is adapted to engage retainer  112 . 
         [0041]      FIG. 3  is an exploded perspective view of handguard system  100  showing additional features not visible in previous figures. In this particular embodiment, fastening feature  204  includes a set of four threaded fasteners  300  and a respective set of four apertures  302 . Each of fasteners  300  includes a first end  304  adapted to be secured to gas tube  200  and a second end  306  adapted to be secured to handguard  202 . In the example embodiment, each of fasteners  300  is a machine screw, wherein first end  304  is a screw head and second end  306  is threaded. Furthermore, each of apertures  302  is a clearance aperture adapted to receive a respective one of fasteners  300 . More specifically, each of apertures  302  is formed through a respective flange  308  defined by exterior surface  210 . Each flange  308  defines a top surface  310  and an opposite bottom surface  312 . Top surface  310  of each flange  308  is adapted to abut the underside of a respective machine screw head. Bottom surfaces  312  are adapted to abut exterior surface  220  of handguard  202 . 
         [0042]    Complementary fastening feature  214  includes a set of four internally threaded apertures  314 , each of which aligns with a respective one of apertures  302  of gas tube  200  and is adapted to receive a second end  306  of a respective one of threaded fasteners  300 . Each of apertures  314  is formed on a respective top surface  316  defined by external surface  214 . Further, each top surface  316  is adapted to abut a respective one of bottom surfaces  312  of flanges  308 . 
         [0043]    As shown, handguard system  100  further includes two set screws  318  and a spring element  320 , both which couple to handguard  202 . Set screws  318  thread into a complementary set of threaded apertures  322  formed through handguard  202 . Set screws  318  facilitate stabilizing and further securing handguard  202  to firearm  102 . That is, when handguard  202  is coupled to firearm  102 , set screws  318  are threaded into apertures  322  and tightened thereby clamping to the trunnion (not shown) mounted within fore-end  116  of receiver  104 . Spring element  320  seats within handguard  202  and further stabilizes handguard  202  by providing an upward biasing force onto the bottom exterior surface of barrel  106 . Spring element  320  facilitates the correct placement and retention of cleaning rod  114  when it is inserted into handguard  202  from fore-end  218 . 
         [0044]      FIG. 4  shows a front perspective view of gas tube  200 . In this particular embodiment, exterior surface of gas tube  200  defines a top region  400 , two side regions  402 , and a bottom region  404 . Top region  400  defines an integral rail  406  that facilitates the mounting of optics and/or other accessories onto gas tube  200 . In this example, rail  406  is a picatinny rail, which is well known in the art. 
         [0045]    Each side region  402  defines a planar surface  408 , a set of vent holes  410 , and two of the four flanges  308 . Planar surface  408  defines a plurality of threaded apertures  412  arranged longitudinally at predetermined distances so as to facilitate the mounting of modular side rails. For example, various length modular rails (not shown) can be attached to side regions  402  of gas tube  200  in various configurations according to the shooters preference. If so desired by the user, the modular side rails can be removed altogether and set screws can be inserted into apertures  412  to protect the threads. Vent holes  410  are located near fore-end  208  and extend through the interior surface  212  so as to allow the expulsion of gas that forces the piston rearward during a shot. 
         [0046]    Bottom region  404  defines a low profile flat surface  414  that provides clearance above barrel  106 . It is important to recognize that gas tube  200  does not mount directly on barrel  106 , as is does in the prior art. This provides many advantages including eliminating direct heat conduction between barrel  106  and gas tube  200 . 
         [0047]      FIG. 5  is a top view of gas tube  200  showing details not visible in previous figures. As previously described, rail  406  is a picatinny rail integrally formed as part of gas tube  200 . Rail  406  includes a plurality of slots  500  and a fore-end  502 . Every other one of slots includes a reference number that facilitates the quick placement of optics and/other tactical accessories. Fore-end  502  includes a surface  504  that is chamfered using a custom revolve cutaway that is complementary in appearance to commonly used gas blocks on AK type rifles. Rear end  206  of gas tube  200  defines opposing flat sides  506  that engage opposing interior wall surfaces of socket  118 . 
         [0048]      FIG. 6  shows a cross-sectional view of gas tube  200  taken along line A-A of  FIG. 5 . Rear end  206  of gas tube  200  includes a downward extending lip  600  and a slot  602  that facilitate the retention of rear end  206  in socket  118 . That is, when rear end  206  is seated in socket  118 , lip  600  prevents horizontal relative motion between gas tube  200  and rear sight block  110 . Slot  602  is adapted to engage a locking pin (not shown) controlled by lever  120 . When lever  120  is in the unlocked position, the locking pin is disengaged from slot  602  thereby permitting rear end to be lifted upward and removed from socket  118 . In contrast, when lever  120  is in the locked position, the locking pin engages slot  602 , thereby preventing vertical motion. 
         [0049]    Interior surface  212  defines a gas block receiving surface  604  and a piston guide feature  606 . Surface  604  is adapted to seat around the exterior surface of the outlet of gas block  108 . Piston guide feature  606  is a  6 -point star shaped bore defined by six channels  608  extending along interior surface  212 . Channels  608  allow excess gas to disperse around the piston (not shown) during operation. Feature  606  is counter bored with a draft angle that allows the piston to travel through both directions unobstructed. 
         [0050]      FIG. 7  shows a front perspective view of handguard  202 . In this particular embodiment, rear end  216  defines a set of rectangular bosses  700  that mate against a block (not shown) located inside of the receiver of certain rifles. Fore-end  218  defines a U-shaped boss  702  that is contoured to seat within handguard retainer  112  of firearm  102 . 
         [0051]    Exterior surface  220  defines a top region  704 , two side regions  706 , a bottom region  708 , and an inner region  710 . Top region  704  is adapted to engage gas tube  200  and defines complementary fastening features  314 . 
         [0052]    Each side region  706  defines a planar surface  712 , and a plurality of vent cutouts  714 . Planar surface  712  defines a plurality of threaded apertures  716  in addition to previously discussed threaded aperture  322  of  FIG. 3 . Threaded apertures  716  are arranged longitudinally at predetermined distances so as to facilitate the mounting of modular side rails. For example, various length modular rails (not shown) can be attached to side regions  706  of handguard  202  in various configurations according to the shooters preference. If so desired by the user, the modular side rails can be removed altogether and set screws can be inserted into apertures  716  to protect the threads. Vent cutouts  714  enable the heat generated by barrel  106  to dissipate while also eliminating unnecessary weight from handguard system  100 . 
         [0053]    Bottom region  708  defines an integral rail  718  that facilitates the mounting of optics and/or other accessories thereon. In this example, rail  718  is also a picatinny rail similar to integral rail  406  of gas tube  200 . 
         [0054]    Inner region  710  defines a main U-shaped channel  720  and a lower U-shaped channel  722 . Channel  720  is adapted to receive barrel  106  and part of spring element  320 . Channel  722  is adapted to receive cleaning rod  114  and part of spring element  320 . 
         [0055]      FIG. 8  is a bottom view of handguard  202  showing details not visible in previous figures. Like rail  406  of gas tube  200 , rail  714  includes a plurality of slots  800 . Every other one of slots  800  includes a reference number that facilitates the quick and proper placement of tactical accessories. 
         [0056]      FIG. 9  shows a top view of handguard  202 , and  FIG. 10  shows a cross-sectional view of handguard  202  taken along line B-B of  FIG. 8 . As shown in  FIG. 9  and  FIG. 10 , inner region  710  defines a cut away  900  and a keyway  902 . Cut away  900  is formed in channel  720  near rear end  216  so as to accommodate for the extra width of front trunnions attached to the barrel on certain rifles. Both the height and width of channel  720  are increased at cut away  900 . Keyway  902  is a thin set of channels adapted to receive spring clip  320 . Further, each channel is cut on an angle so as to intersect the walls of inner region  710  on each side. 
         [0057]      FIG. 11  shows a front perspective view of spring clip  320  which, for example, is formed from a flat rectangular shaped piece of steel that is longitudinally formed to a certain radius. The radius is sufficient to provide a firm fit when inserted into the keyway  902 . Spring clip  320  includes two opposing side edges  1100 , a rear end  1102 , and a fore-end  1104 . When spring clip  320  is inserted into keyway  902 , each of edges  1100  is firmly engaged by a respective side channel of keyway  902 . Rear end  1102  defines an elbow  1106  that is adapted to engage cleaning rod  114 . Fore-end  1104  is adapted to engage the bottom of barrel  106 . Optionally, a radius can be added to fore-end  1104 , to prevent scratching the exterior surface of the barrel  106 . 
         [0058]      FIG. 12  shows a front view of handguard system  100  assembled. As shown, elbow  1106  protrudes into lower channel  722  such that when cleaning rod  114  is inserted, elbow  1106  forces it into its correct position and retains it. Fore-end  1104  of spring clip  320  has a length sufficient to extend into channel  720  such that it is urged downward by barrel  106  when handguard system  100  is mounted to firearm  102 . In response to being deflected downward, fore-end  1104  maintains a constant upward spring force on the bottom of barrel  106  thereby providing stability. It should be noted that although spring clip  320  contacts barrel  106 , gas tube  200  and handguard  202  do not. It should also be noted that gas tube  200  and handguard  202  have the same width thus giving handguard system  100  a compact profile. 
         [0059]      FIG. 13  shows a perspective cross-sectional view of handguard system  100  and  FIG. 14  shows a side cross-sectional view of handguard system  100  taken along line C-C of  FIG. 12 . It should be recognized that in the example illustrations of  FIG. 13  and  FIG. 14 , spring clip  320  is not shown sectioned. Spring clip  320  is shown seated in handguard  202  wherein one of edges  1100  is inserted into a respective one of two side channels of keyway  902 . 
         [0060]    The assembly of handguard system  100  is described with reference to  FIGS. 1-13 . Fore-end  1104  of spring clip  320  is inserted into the keyway  902 . Rear end  216  of handguard  202  is coupled to fore-end  116  of receiver  104  and raised up parallel to barrel  106 . Handguard retainer  112  is slid over U-shaped boss  702 , and lever  124  is then locked. Next, fore-end  208  of gas tube  200  is inserted over the outer diameter of gas block  108 . Then, rear end  206  of gas tube  200  is lowered into socket  118 , lever  120  is moved into the locked position. Finally, gas tube  200  is attached to handguard  202  via fasteners  300 , and set screws  318  are tightened against the front trunnion (not shown) of firearm  100 . 
         [0061]    The description of particular embodiments of the present invention is now complete. Many of the described features may be substituted, altered or omitted without departing from the scope of the invention. For example, alternate firearm models (e.g., AK-74), may be substituted for the AK-47 firearm  100 . As another example, other rail systems (e.g., weaver rail), may be substituted for the picatinny rail systems  406  and  718 . These and other deviations from the particular embodiments shown will be apparent to those skilled in the art, particularly in view of the foregoing disclosure.