Abstract:
A quick release, free floating, multi-piece forward hand guard assembly for a rifle includes an inner barrel nut adapted to be affixed to a front of the rifle receiver and an outer barrel nut telescopically received over the inner barrel nut and longitudinally secured thereto. The outer barrel nut is non-rotatable with respect to the inner barrel nut. A first hand guard element is engaged with and extends forwardly from the outer barrel nut in a laterally stable cantilevered fashion, and a second hand guard element is matingly engaged with the first hand guard element for surrounding the rifle&#39;s barrel and is free floating therefrom. The second hand guard element is attached to the first hand guard element with at least one quick release fastener.

Description:
FIELD OF THE INVENTION 
     The present disclosure generally relates to gunstocks for rifles. More particularly, the present disclosure relates to a two-piece cantilevered forward shield for an automatic rifle. 
     BACKGROUND OF THE INVENTION 
     Gunstocks for handheld weapons date back to the sixteenth century and are derived from the Germanic word ‘stoc’, meaning tree trunk, referring to the wooden nature of the gunstock. Those early ‘hand cannons’ used a simple stick fitted into a socket in the breech end of the weapon to provide a handle for the user. Over the following centuries, gunstocks typically remained fashioned from wood, although the shape of the gunstock evolved to the gunstock of the twentieth century that is most recognizable with a butt stock for placing against a shooter&#39;s shoulder including a grip and a fore end or hand guard. Initially, gunstocks were one piece from butt to fore end, but certain weapon configurations lent themselves to two-piece stocks where the fore end was separate from the butt and grip. 
     The evolution of the rifle, and especially with respect to the genre of weapons categorized as assault rifles or assault weapons, has resulted in the use of gunstock hand guards that are separate from the remaining stock members. Particularly, these modern weapons are generally militarized weapons and are utilized by and mass-produced for arming of a country&#39;s armed forces. While traditional gunstocks have been machined from wooden blanks, consideration for weapon quantities, durability in adverse environments, ease of fabrication, and versatility have relegated the wooden gunstock in military weapons to the annals of history. Today&#39;s gunstocks are typically formed of metal, injection molded thermoplastic, or a combination of the two. 
     In particular, the separate gunstock hand guard fulfills multiple functions. The primary purpose of the hand guard is to insulate the shooter&#39;s hand from the heat of the rifle barrel. Secondly, the hand guard can include provisions for mounting accessories to the weapon such as, for example, a flashlight aligned with the barrel to illuminate the area in front of the weapon in low light or dark lighting conditions. Initially, on early rifles, such provisions were almost exclusively used for mounting telescopic sights and were thus formed on the top portion of the rifle&#39;s receiver. However, for militarized assault rifles such as the M16, these provisions are found on the hand guard and are commonly known as Picatinny rails. One or more Picatinny rails can usually be found on each hand guard. Picatinny rails (developed at the Picatinny Arsenal) are standardized, the dimensional specifications being found in MIL-STD-1913 or STANAG 2324. Hand guards can be either permanently mounted to the weapon or can be of a “quick attach/detach” design. 
     With normal rifles, the barrel rests in contact with the stock and in particular with the fore end or hand guard portion of the stock. If the stock is manufactured of wood, environmental conditions or operational use may shift the alignment of the stock, which, in turn, may cause the barrel to shift its alignment slightly over time. This shift can alter the flight path of the projectile and thus its impact point. Contact between the barrel and the stock also interferes with the natural frequency of the barrel, which, in some cases, can be detrimental on the weapon&#39;s accuracy. The interference of the stock with the barrel&#39;s forced oscillation as the projectile passes down the bore can cause the barrel to vibrate inconsistently from shot to shot, depending on the external forces acting upon the stock at the time of the shot. Micro-vibrations acting during the projectile&#39;s passage result in differences in trajectory as the projectile exits the bore, thus changing the downrange impact point. 
     One method of minimizing this detrimental interference between the hand guard and the barrel has been to free float the barrel with respect to the hand guard. Specifically, the barrel and the hand guard are each independently affixed to the weapon&#39;s receiver and project forward from the receiver in cantilevered fashion. The barrel and stock are designed to not touch at any point along the barrel&#39;s length. The barrel is “free floating” and does not contact other gun parts, other than the weapon&#39;s front sight. The free floating of the barrel minimizes possible mechanical pressure distortions of the barrel alignment, and allows vibration to occur at the barrel&#39;s natural frequency. The trend has been to outfit these weapons with free-floating barrels and hand guards. However, to maintain stability of the free floating hand guard, the attachment of the hand guard has typically been of a permanent attachment, or alternatively of a one-piece quick attach design to prevent the lateral shifting of hand guard elements with respect to each other in multiple-piece hand guards. 
     Single piece hand guards, even if quickly detachable, typically also require the highly undesirable removal of the front sight from the barrel in order to facilitate total removal. Conversely, quickly detachable hand guards of a multiple piece (usually two pieces) design are not free floating and are typically attached to the front end of the barrel. Therefore, a free floating, quick attach hand guard that is also stable and of a two-piece design is needed. 
     SUMMARY OF THE INVENTION 
     The present disclosure is generally directed to a quick release, free floating, multi-piece forward hand guard assembly for a rifle. The hand guard assembly includes an inner barrel nut adapted to be affixed to a front of the rifle receiver and an outer barrel nut telescopically received over the inner barrel nut and longitudinally secured thereto. The outer barrel nut is non-rotatable with respect to the inner barrel nut. A first hand guard element is engaged with and extends forwardly from the outer barrel nut in a laterally stable cantilevered fashion, and a second hand guard element is matingly engaged with the first hand guard element for surrounding the rifle&#39;s barrel and is free floating therefrom. The second hand guard element is attached to the first hand guard element with at least one quick release fastener. 
     In another aspect, a rifle of the type having a receiver and a barrel extending from a front portion of the receiver includes a quick release, free floating, multi-piece forward hand guard assembly affixed to the receiver. The hand guard assembly comprises an inner barrel nut removably affixed to the front portion of the receiver and an outer barrel nut is telescopically received over the inner barrel nut and longitudinally secured thereto. The outer barrel nut includes rearwardly extending tabs laterally spaced one from the other and closely receiving the front portion of the receiver therebetween. First and second hand guard elements are attached one to the other with at least one quick release fastener wherein the elements in combination encircle the barrel and have one end secured to the outer barrel nut and have a second end free floating with respect to the barrel in a laterally stable cantilevered fashion. 
     These and other features, aspects, and advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described, by way of example, with reference to the accompanying drawings, where like numerals denote like elements and in which: 
         FIG. 1  presents a rear perspective view of a rifle hand guard assembly embodying the present invention wherein the front of the hand guard is free floating and the hand guard is quickly detachable from the rifle; 
         FIG. 2  presents an exploded front perspective view of the free floating hand guard; 
         FIG. 3  presents a bottom rear perspective view of the inner barrel nut; 
         FIG. 4  presents an elevation view of the inner barrel nut; 
         FIG. 5  presents a rear perspective view of the outer barrel nut and rotated ninety degrees clockwise; 
         FIG. 6  presents a side elevation view of the assembled hand guard; 
         FIG. 7  presents a cross-sectional view of the hand guard shown in  FIG. 6  and taken along the line  7 - 7 ,  FIG. 6 ; 
         FIG. 8  presents a side elevation view of an assault weapon with the hand guard of  FIG. 1  attached thereto; 
         FIG. 9  is an enlarged view of the attached hand guard of  FIG. 8 . 
     
    
    
     Like reference numerals refer to like parts throughout the various views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. For purposes of description herein, the terms “upper”, “lower”, “left”, “rear”, “right”, “front”, “vertical”, “horizontal”, and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     Turning to the drawings,  FIG. 1  shows a hand guard assembly  120  (the inner barrel nut  150  has been removed for clarity), which is one of the preferred embodiments of the present invention and illustrates its various components. Referring to  FIGS. 1-7 , hand guard assembly  120  includes, as most clearly seen in  FIGS. 3-4 , an inner barrel nut  150 . Inner barrel nut  150  has a generally tubular configuration defining a central passage  151  with an internal female thread  152  at a rear end  160  to mate with and receive the male threads of the forward end  104  of a receiver  102  of rifle  100  ( FIG. 8 ). The tubular configuration of barrel nut  150  includes a central axis  128 , which corresponds to the central axis of hand guard assembly  120  and to the central axis of the bore of rifle barrel  106 . Those practiced in the art will readily understand that the external male threads on receiver  104  may be different on different rifle designs and therefore that internal threads  152  may be adapted to the particular design of rifle  100  so that inner barrel nut  150  may be securely affixed to receiver  104  ( FIG. 8 ). Central passage  151  permits inner barrel nut  150  to be sleeved over barrel  106  of rifle  100 . Barrel nut  150  may7 also include a slot  154  for receiving an end of a spanner wrench (not shown) for tightening inner barrel nut  150  onto receiver  104  in a manner common to and known to those practiced in the art. Inner barrel nut  150  further defines at least one and most preferably two grooves  156 ,  158  axially or longitudinally spaced one from the other and extending about an external periphery of barrel nut  150 . 
     Referring now to  FIG. 5 , outer barrel nut  170  is shown in rear perspective and rotated ninety degrees clockwise to most clearly illustrate its features. Outer barrel nut  170  defines a central passageway  171  having a diameter to closely receive inner barrel nut  150  therein in a telescopic manner. A rear end  184  of outer barrel nut  170  includes two rearwardly projecting tabs  180 ,  182  which are laterally spaced one from the other. The spacing of tabs  180 ,  182  is such to closely receive therebetween a forward portion of receiver  104  of rifle  100 . Outer barrel nut  170  also includes a top axial rib  172  and a bottom axial rib  174 . Bottom axial rib  174  further defines two holes  176  extending therethrough, each hole  176  threaded to receive a set screw (not shown) therein. A plurality of grooves  178  extend about at least a portion of the external periphery of outer barrel nut  170 , grooves  178  being substantially identical one with the other and equally spaced along the length of outer barrel nut  170 . Outer barrel nut  170  further acts as a heat sink for the heat energy generated by the hot gasses and friction of the projectiles traveling through the bore of barrel  106  to insulate the high temperature generated from firing rifle  100  to the user&#39;s hands grasping hand guard assembly  120 . 
     Hand guard  121  is a combination of hand guard elements  130 ,  140 , which are most clearly illustrated in  FIG. 2  wherein top hand guard element  130  has a generally semi-tubular configuration. Top hand guard element  130  includes an axially aligned accessory rail  126  extending along a top surface of hand guard element  130 . Accessory rail  126  may be of any configuration that accepts accessories adapted for mounting on a rifle such as telescopic sights, flashlights, etc. As such, and as shown, accessory rails  126  shown on hand guard  121  conform to MIL-STD-1913 or STANAG 2324, the details of which are well known in the art and are not described further herein. The semi-tubular configuration of top guard element  130  has a mating edge  132  along each side of element  130  and at least one and preferably a plurality of regularly spaced alignment pins  134  extending downwardly from edge  132 . Top hand guard element  130  defines, at an inner top portion, an axially or longitudinally aligned channel  136  sized to closely receive top axial rib  172  of outer barrel nut  170 . 
     Bottom hand guard element  140  also has a generally semi-tubular configuration and can include, as shown, multiple accessory rails  126  spaced about the periphery thereof. Bottom hand guard element  140  also includes a mating edge  142  along each side thereof. Mating edge  142  defines a plurality of alignment holes  144  therealong and regularly spaced to receive alignment pins  134  of top hand guard  130  and to securely seat top mating edges  132  against bottom mating edges  142  when top hand guard element  130  and bottom hand guard element  140  are combined to form hand guard  121 . As most clearly illustrated in  FIG. 2 , bottom hand guard element  140  includes a plurality of axially spaced inner circumferential ribs  148 . Ribs  148  are spaced to engage grooves  178  in outer barrel nut  170 . Although not specifically illustrated, top hand guard element  130  includes a like number and like configured ribs as ribs  148  interior to top hand guard  130 . 
     Elements  130 ,  140  are secured one to the other with at least one and preferably two quick release fasteners  190  positioned at a rear  124  of hand guard  121 . While quick release faster  190  may be of any design facilitating the quick disassembly and subsequent assembly of hand guard elements  130 ,  140  one to the other, as shown, a quick release fastener  190  is positioned on each lateral side of hand guard  121  and is of an over-centering latch design known in the art and particularly adapted to be substantially conformal with the external shape of hand guard  121 . In particular, over-centering latch  190  includes a movable wire form  193  and rotatably retained in a latch base  192  affixed to top hand guard element  130 . A latch lever  194  is rotatably retained at an outer end of wire form  193  such that a lever end  195  can engage a hook  149  integrally formed at a rear portion  124  of bottom hand guard  140 . The size and positioning of the elements of over-centering latch  190  are such that when latch lever  194  is fully engaged in hook  149  and closed, top hand guard element  130  is securely held in combination with bottom hand guard element  140  to form hand guard  121 . 
     In use, and referring to FIGS.  1  and  6 - 9 , hand guard assembly  120  is affixed to rifle  100  in the following manner. The rear portion  160  of inner barrel nut  150  is threaded onto the male threads of the front portion  104  of receiver  102  of rifle  100  (or affixed by the particular attachment provisions of a different design receiver). A spanner wrench (not shown) engages slot  154  whereby inner barrel nut  150  is securely torqued onto receiver  102 . 
     Outer barrel nut (heat sink)  170  is telescoped over inner barrel nut  150  such that top axial rib  172  and tabs  180 ,  182  are oriented up. Outer barrel nut  170  is translated axially back such that the upper forward portion  104  of receiver  102  is captured between tabs  180 ,  182  and axially positioned such that holes  176  are in registration with grooves  156 ,  158  of inner barrel nut  150 . Set screws (not shown) are then threaded into holes  176  and torqued to securely seat in grooves  156 ,  158  respectively. In this manner, tabs  180 ,  182  closely receiving front portion  104  of receiver  102  prevents outer barrel nut from rotating about inner barrel nut  170 , and set screws firmly torqued in holes  176  to engage grooves  156 ,  158  of inner barrel nut  150  maintain outer barrel nut  170  in a fixed longitudinal position with respect to inner barrel nut  150 . 
     The rear portion of bottom hand guard element  140  is engaged with the bottom portion of outer barrel nut  170  by closely engaging bottom axial rib  174  of outer barrel nut  170  in channel  146  of bottom hand guard element  140 . Axial rib  174 , engaged in channel  146 , prevents lateral movement of bottom hand guard element  140  with respect to outer barrel nut  170 . Further, bottom hand guard element  140  is axially adjusted such that inner circumferential ribs  148  are engaged in grooves  178  of outer barrel nut  170 . The engagement of inner circumferential ribs  148  in grooves  178  prevents axial or longitudinal movement of bottom hand guard element  140  with respect to outer barrel nut  170 . Once bottom hand guard element  140  is engaged with the bottom of outer barrel nut  170 , top hand guard element  130  is similarly engaged with outer barrel nut  170 . Specifically, top axial rib  172  of outer barrel nut is received in channel  136  of top hand guard element  130 , and the inner circumferential ribs (not shown) are engaged in grooves  178  of outer barrel nut  170 . Further, alignment pins  134  of top hand guard element  130  are received in alignment holes  144  of bottom hand guard element  140  to laterally secure top hand guard element  130  with respect to bottom hand guard element  140 . 
     Once top and bottom hand guard elements  130 ,  140  are correctly positioned one to the other and on outer barrel nut  170 , lever end  195  of each over-centering latch  190  is engaged in the respective hooks  149  of bottom hand guard element  140  and latch lever  194  is rotated to its over-center position securing top hand guard element  130  to bottom hand guard element  140  to form hand guard  121 . In this manner hand guard  121  is also rigidly secured to outer barrel nut  170  such that the front end  122  of hand guard  121  is cantilevered over barrel  106  of rifle  100  and is free floating with respect to barrel  106  and all support for hand guard  121  is provided by inner and outer barrel nuts  150 ,  170 . Top and bottom hand guard elements  130 ,  140  can be quickly removed by releasing over-centering latches  190  and disassembling hand guard  121  in reverse order as described above. Inner and outer barrel nuts  150 ,  170  can remain attached to receiver  102  and do not require removal to facilitate the removal of hand guard  121 . 
     Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalence.