Abstract:
Firearm weights and firearm rails having one or more weights that hug the interior surface of the firearm rail and/or orient a firearm sling loop in an appropriate position on the firearm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 29/514,838 filed Jan. 16, 2015. This application is also a continuation-in-part of U.S. patent application Ser. No. 29/514,853 filed Jan. 16, 2015. The disclosures of the foregoing applications are hereby incorporated by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    Shooting a firearm generates exploding gases that result in a recoil or “kick” of the firearm after each shot. The displacement of the firearm occasioned by recoil can hinder projectile accuracy, particularly during rapid fire in which multiple shots in quick succession create a cumulative recoil effect that tends to cause the firearm to move or “walk” away from the target. Adding weight to the firearm, and especially to certain portions of the firearm, can reduce these negative effects of recoil. Adding weight to a firearm can be particularly advantageous in a situation when the weight of the firearm is not being carried partially or entirely by the shooter, for example in the context of a shooting competition in which the firearm rests on the ground or rests on a structure which, in turn, rests on or is connected to the ground, such as a bipod or tripod. There is a need for firearm weights that are easily installed and removed; firearm weights that are adjustable to a desired weight distribution; and firearm weights that do not expand the profile of the firearm. 
         [0003]    Additionally, firearms can be slung over the shooter&#39;s shoulder with a sling, the sling being connected to the firearm. Common problems associated with firearm slings include the heft and bulkiness of the mechanism used to attach the sling to the firearm, as well as the difficulty of securing the sling at an appropriate position on the firearm when the firearm is used in shooting competitions. 
       SUMMARY 
       [0004]    In general terms, this disclosure is directed to firearm rails and firearm rail weights. 
         [0005]    In one aspect, a firearm weight includes an elongate member having a front end and a rear end, the elongate member configured to be detachably secured to an interior surface of a firearm rail; and a sling loop, the sling loop being pivotably attached to the front end of the elongate member. 
         [0006]    In another aspect, a firearm weight system includes a first firearm weight comprising an elongate member having a front end and a rear end, the elongate member configured to be detachably secured to a first portion of an interior surface of a firearm rail, and a sling loop, the sling loop being pivotably attached to the front end of the first firearm weight; a second firearm weight comprising an elongate member having a front end and a rear end, and a flange extending from the elongate member that is configured to be detachably secured to a second portion of the interior surface of the firearm rail; and a third firearm weight comprising an elongate member having a front end and a rear end, and a flange extending from the elongate member that is configured to be detachably secured to a third portion of the interior side of the firearm rail. 
         [0007]    In a further aspect, a firearm rail includes an interior surface having at least one longitudinally extending slot; and a weight comprising an elongate member having a front end and a rear end, the elongate member being detachably secured in the at least one slot. 
         [0008]    In yet a further aspect, a firearm weight comprises an elongate member having a front end and a rear end; and a flange extending from the elongate member and configured to be detachably secured to an interior surface of a firearm rail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a front, top, left side, perspective view of an example firearm with firearm weights consistent with the present disclosure. 
           [0010]      FIG. 2  is a front view of the example firearm of  FIG. 1  with firearm weights consistent with the present disclosure. 
           [0011]      FIG. 3  is a front, top, left side perspective view of an example firearm rail with firearm weights consistent with the present disclosure. 
           [0012]      FIG. 4  is a front view of the firearm rail and weights combination of  FIG. 3 . 
           [0013]      FIG. 5 . is a front, bottom, left side perspective view of a combination of an example bottom weight for a firearm rail and a sling loop in accordance with the present disclosure. 
           [0014]      FIG. 6  is a rear, top, left side perspective view of the combination bottom weight and sling loop of  FIG. 5 . 
           [0015]      FIG. 7  is a front, top perspective view of an example side weight for a firearm rail in accordance with the present disclosure. 
           [0016]      FIG. 8  is a rear, bottom, perspective view of the side weight of  FIG. 7 . 
           [0017]      FIG. 9  is a bottom view of a combination of the example bottom weight for a firearm rail and a sling loop of  FIG. 5 . 
           [0018]      FIG. 10  is a bottom view of the example side weight of  FIG. 7 . 
           [0019]      FIG. 11  is a front view of the example side weight of  FIG. 7 . 
           [0020]      FIG. 12  is an exploded view of a firearm rail in combination with a barrel nut and example side weights and bottom weight with sling loop in accordance with the present disclosure, illustrating how the barrel nut and weights are installed in the firearm rail. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Various embodiments are described herein in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the appended claims. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims. 
         [0022]      FIG. 1  is a front, top, left side, perspective view of an example firearm  100  with firearm weights consistent with the present disclosure. In this example, the firearm  100  includes an upper receiver  102 , a lower receiver  104 , a barrel  106 , a muzzle  108 , a stock  110 , a rail  112 , side weights  114   a  and  114   b , a bottom weight  116 , a sling  118 , a front sling loop  120 , and a rear sling loop  122 . The lower receiver  104  includes a trigger mechanism  124 , a magazine well  126 , and a magazine  128 . The rail  112  includes a top side  130 , a bottom side  132 , a left side  134 , a right side  136 , heat vents  138 , an interior surface  140 , an interior bore  141 , a rear end  142 , and a front end  144 . Each of the top side  130 , the bottom side  132 , the left side  134 , and the right side  136  of the rail  112  includes mounting ribs  146 . 
         [0023]    The firearm  100  can be of a variety of types. Examples of the firearm  100  include, but are not limited to, handguns, rifles, shotguns, carbines, machine guns, submachine guns, personal defense weapons, automatic rifles, and assault rifles. In at least one embodiment, the firearm  100  is an AR-15, M-16 or M-4 type rifle, or one of their variants. 
         [0024]    The upper receiver  102  defines an internal longitudinally-extending cavity configured to receive a bolt assembly. The bolt assembly is slidably disposed in the cavity for axially reciprocating recoil movement therein. In at least one embodiment, the upper receiver  102  is an AR-15, M-16 or M-4 type upper receiver, or one of their variants. 
         [0025]    The lower receiver  104  is situated below the upper receiver  102  and is involved in triggering the firearm  100 . The barrel  106  includes an internal, longitudinally extending bore that ends at the muzzle  108  at the front of firearm  100 , where a projectile (e.g., a bullet) exits the firearm. The barrel  106  is in open communication with the upper receiver  102 . 
         [0026]    The upper receiver  102  and the lower receiver  104  are configured to house a firing mechanism and associated components as found in, for example, AR-15, M-16 or M-4 type rifles and their variants. Such a firing mechanism typically includes a spring-biased hammer that is cocked and then released by a sear upon actuating a triggering mechanism. The hammer strikes a firing pin carried by a bolt, which in turn is thrust forward to contact and discharge a cartridge loaded in a chamber. A portion of the expanding combustion gases traveling down the barrel is discharged off and used to drive the bolt rearward against a forward biasing force of a recoil spring for automatically ejecting the spent cartridge casing and automatically loading a new cartridge into the chamber from a magazine when the bolt returns forward. 
         [0027]    The stock  110  surrounds a buffer tube extending from the rear of upper receiver  102 . Buffer tubes typically include a buffer pin, a buffer spring for recoil reduction, as well as a castle nut and an endplate. The stock  110  provides support to the operator holding the firearm  100  to steady and aim the firearm  100  during firing. The stock  110  also operates to transmit recoil generated from firing the firearm to the body of the shooter. 
         [0028]    The rail  112  surrounds at least a portion of barrel  106 . The rail  112  can be used as a place to hold the front portion of the firearm  100  during use, and can function as a guard to protect the firearm user&#39;s hand from the heat of the barrel  106  while shooting the firearm. In addition, the rail  112  can function as a mounting platform for firearm accessories, such as a bipod, tripod, light, hand grip, sight, optic, optic platform, infrared laser, magnifier, and so forth. 
         [0029]    The example side weights  114   a  and  114   b  are detachably secured inside the rail  112  and provide weight to the firearm  100 . The side weights  114   a  and  114   b  can shift the center of gravity of the firearm  100 , and can help to reduce the negative effects of recoil generated from firing the firearm  100 . The bottom weight  116  is also detachably secured inside the rail  112  and provides weight to the firearm  100 . The bottom weight  116  can also shift the center of gravity of the firearm  100 , and can help to reduce the negative effects of recoil generated from firing the firearm  100 . 
         [0030]    The sling  118  is a looped strap that can be slung over the shooter&#39;s shoulder when carrying or using the firearm  100  in order to help steady the firearm  100  and/or transfer some of the firearm&#39;s weight to the user&#39;s shoulder. The example sling  118  attaches to the firearm  100  by looping through the front sling loop  120  and the rear sling loop  122 . In this example, the front sling loop  120  is pivotably coupled to the bottom weight  116 , and the rear sling loop  122  is coupled to the stock  110 . In this manner, the weight of the sling  118  hangs from the bottom weight  116  and the stock  110 . 
         [0031]    The trigger mechanism  124  of the lower receiver  104  operates the trigger of the firearm  100 . The magazine well  126  in the lower receiver  104  houses the magazine  128 , which in turn holds projectiles for shooting from the firearm  100 . 
         [0032]    The example rail  112  includes four sides—a top side  130 , a bottom side  132 , a left side  134 , and a right side  136 . Among these four sides, adjacent sides are spaced apart from each other and equidistant (i.e. at 90° angles) from each other. In this example, the rail  112  is secured to a barrel nut (see discussion below in connection with  FIG. 12 ), which in turn secures the barrel  106  to the upper receiver  102 . The heat vents  138  are openings that line the spaces between each adjacent pairs of the four sides  130 ,  132 ,  134 , and  136 . The heat vents  138  allow heat radiating from the barrel  106  as a result of shooting the firearm  100  to escape, thereby preventing excessive heat build-up between the rail  112  and the barrel  106 . The interior surface  140  of the rail  112  surrounds the interior bore  141 . The interior bore  141  of the rail  112  extends from the rear end  142  to the front end  144  of the rail  112 . In this example, the rear end  142  of the rail  112  abuts the upper receiver  102 , and the barrel  106  extends through the entirety of interior bore  141  and beyond the front end  144  of the rail  112 . In this example, the mounting ribs  146  alternate with grooves and line each of the four sides  130 ,  132 ,  134 , and  136  of the rail  112 . The mounting ribs  146  with their corresponding grooves provide a platform for mounting firearm accessories having corresponding ribs and grooves that engage the grooves and mounting ribs  146 , respectively, of rail  112 . Example accessories that can be mounted in this manner to the rail  112  include, without limitation, a bipod, tripod, light, hand grip, sight, optic, optic platform, infrared laser, and magnifier. In one example, the mounting ribs  146  are standard dimension such as a “Picatinny” style mounting platform, also known as MIL-STD-1913. 
         [0033]      FIG. 2  is a front view of the example firearm  100  of  FIG. 1  with firearm weights consistent with the present disclosure. The firearm  100  includes the barrel  106 , the stock  110 , the rail  112 , the side weights  114   a  and  114   b , the bottom weight  116 , the sling  118 , the front sling loop  120 , and the rear sling loop  122  as discussed above. In addition, the rail  112  includes the top side  130 , the bottom side  132 , the left side  134 , the right side  136 , the interior surface  140 , and the interior bore  141  as discussed above. In addition, in this example, the rail  112  includes a top right side  160 , a top left side  162 , a bottom left side  164 , and a bottom right side  166 . 
         [0034]    In this example firearm  100 , the top right side  160  of the example rail  112  is recessed between the top side  130  and the right side  132  of the rail  112 . The top left side  162  is recessed between the top side  130  and the left side  134  of the rail  112 . The bottom left side  164  is recessed between the bottom side  132  and the left side  134  of the rail  112 . The bottom right side  166  is recessed between the bottom side  132  and the right side  136  of the rail  112 . In this example rail  112 , heat vents (such as the heat vents  138  discussed above in connection with  FIG. 1 ) are lined along each of the top right side  160 , the top left side  162 , the bottom left side  164 , and the bottom right side  166  of the rail  112 . 
         [0035]    As also shown in  FIG. 2 , in this example firearm  100 , the side weight  114   a  is inside the interior bore  141  and abuts the interior surface  140  of the rail  112  on the right side of the barrel  106 , and the side weight  114   b  is inside interior bore  141  and abuts the interior surface  140  of the rail  112  along the left side of the barrel  106 . In addition, the bottom weight  116  is inside the interior bore  141  and abuts the interior surface  140  of the rail  112  below the barrel  106 . Installing the side weights  114   a  and  114   b  and the bottom weight  116  within the rail  112  avoids expanding the exterior profile of the firearm  100  as compared with, e.g., mounting or installing a firearm weight to the exterior of a firearm or a firearm component. Reducing the extent of a firearm&#39;s profile can improve the appearance of the firearm and also help to avoid undesirable snagging of the firearm while carrying it. 
         [0036]      FIG. 3  is a front, top, left side perspective view of an example firearm rail  112  with firearm weights consistent with the present disclosure. The example rail  112  includes the top side  130 , the bottom side  132 , the left side  134 , the right side  136 , the heat vents  138 , the interior surface  140 , the interior bore  141 , the rear end  142 , the front end  144 , and the mounting ribs  146  as discussed above. The side weights  114   a  and  114   b , and the bottom weight  116  including the front sling loop  120 , as discussed above, are also shown. In addition, in this example the rail/weights combination includes side weight fasteners  180 , and barrel nut fasteners  182 . 
         [0037]    The side weight fasteners  180  secure the side weight  114   b  to the interior surface  140  of the rail  112 . A corresponding set of side weight fasteners (not shown) secures the side weight  114   a  to the interior surface  140  of the rail  112 . In one example, the side weight fasteners  180  are screws that are inserted into openings in the left side  134  and the right side  136  of the rail  112  and then enter threaded openings in the side weights  114   a  and  114   b  respectively. In this example, the openings in the rail used for this purpose are drilled between adjacent pairs of mounting ribs  146  on the left side  134  and the right side  136 , respectively, of the rail  112 . In one example, opposing inner sides of the aforementioned adjacent pairs of mounting ribs are carved out to accommodate a fastener head that may be larger than the opening through which the fastener is inserted. This allows the fastener head to abut the bottom surface of the groove between the pair of adjacent mounting ribs  146 , which in turn provides a more secure interface between the side weight  114   a  or  114   b  and the interior surface  140  of the rail  112 . 
         [0038]    The barrel nut fasteners  182  secure the rail  112  to a barrel nut (not shown) at the rear end of a firearm barrel. In one example, the barrel nut fasteners  182  are a dual bolt and nut mechanism consisting of a pair of bolts extending through the width of the rail  112  from the right side  136  to the left side  134 , with each of a pair of nuts securing each of the bolts in place, respectively. In this example, as the bolts pass through the rail  112 , they engage grooves in a barrel nut (as discussed below in more detail in connection with  FIG. 12 ), thereby preventing movement of the rail relative to the barrel nut and barrel. 
         [0039]      FIG. 4  is a front view of the firearm rail and weights combination of  FIG. 3 . The combination includes the firearm rail  112 , the side weights  114   a  and  114   b , and the bottom weight  116  including the front sling loop  120 , as discussed above. The rail  112  includes the top side  130 , the bottom side  132 , the left side  134 , the right side  136 , the interior surface  140 , the interior bore  141 , the top right side  160 , the top left side  162 , the bottom left side  164 , and the bottom right side  166 , as also discussed above. In this example, the interior bore  141  of the rail  112  also includes an upper channel  190 ; the side weight  114   a  includes an interiorly facing curved surface  192   a ; the side weight  114   b  includes an interiorly facing curved surface  192   b ; and the bottom weight  116  includes a top surface  194 . 
         [0040]    In this example firearm rail and weights combination, the upper channel  190  is an extension of the interior bore  141  and is situated directly below the upper side  130  of the rail  112 . Typically, the upper channel  190  is used to accommodate firearm barrel attachments, such as a gas tube (which operates to divert some of the gases generated from a fired projectile back into a firearm upper receiver to assist in cycling the firearm for repeated firing), that are positioned on top of a barrel (such as the barrel  106  in  FIG. 2 ). 
         [0041]    When a barrel of a firearm (such as barrel  106  in  FIGS. 1-2 ) is housed in the rail/weights combination of  FIG. 4 , the interiorly facing curved surface  192   a  of the side weight  114   a  follows the contour of the barrel&#39;s exterior surface on the barrel&#39;s right side, the interiorly facing curved surface  192   b  of the side weight  114   b  follows the contour of the barrel&#39;s exterior surface on the barrel&#39;s left side, and the top surface  194  of the bottom weight  116  faces the bottom of the barrel&#39;s exterior surface. This allows sufficient empty space in the interior bore  141  of the rail  112  for the rail  112  to house the barrel  106 . In some example embodiments, at least a portion of one or more of the interiorly facing curved surfaces  192   a  and  192   b  and top surface  194  abuts the exterior of the barrel. In other example embodiments, there is no contact between one or more of the side weights  114   a  and  114   b  and the bottom weight  116 , on the one hand, and the barrel on the other hand, such that a gap of air separates one or more of the weights from the barrel. 
         [0042]      FIG. 5 . is a front, bottom, left side perspective view of a combination of an example bottom weight  116  for a firearm rail  112  and a sling loop  120  in accordance with the present disclosure;  FIG. 6  is a rear, top, left side perspective view of the combination bottom weight  116  and sling loop  120  of  FIG. 5 .  FIGS. 5 and 6  show example bottom weight  116 , front sling loop  120 , and top surface  194  as discussed above. In addition, in this example, the bottom weight  116  includes an elongate member  200 , a rear end  201 , a front end  202 , a left surface  204 , a right surface  206 , a bottom surface  208 , chamfers  210   a  and  210   b , screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e , a cutout  214  and a pin hole  216 . Additionally in this example, the front sling loop  120  includes a sleeve  218 , and a pin  220 . 
         [0043]    The elongate member  200  of the example bottom weight  116  is configured to be inserted into and housed in a slot at the bottom of a firearm rail. In some embodiments, the elongate member  200  is made from a relatively dense material to provide weight and strength to the rail in which it is housed and to which it is secured. In on example, the elongate member  200  is steel. The elongate member  200  has a thickness T 1  as measured between the bottom surface  208  and the top surface  194 . T 1  can be a variety of suitable thicknesses. In some examples, T 1  is in a range from about 5 mm to about 15 mm. In one example embodiment, T 1  is about 9 mm. In some examples T 1  corresponds to the distance between a deepest surface of the bottom slot  272  (see  FIG. 12 ) in the rail  112  (see  FIG. 12 ) and the exterior surface of a barrel (e.g. the barrel  106  in  FIG. 1 ) that is inserted in the rail  112 . 
         [0044]    The example bottom weight  116  is cast or otherwise shaped from metal or a metal alloy, such as steel. In one example embodiment of the bottom weight  116 , all features of the bottom weight are cast together in a single mold. In alternative embodiments, one or more features of the bottom weight  116  are machined from barstock or following the casting process, such as the chamfers  210   a  and  210   b , the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e , the cutout  214  and/or the pin hole  216 . In alternative examples, other suitably heavy, strong, and rigid materials may be used for the bottom weight  116 . 
         [0045]    In one example configuration, the bottom weight  116  is inserted into a rail from its rear end  201  first. When fully inserted in the rail, the front end  202  of the bottom weight  116  protrudes somewhat from the front of the rail (such as rail  112  in  FIG. 3 ). In addition, when fully inserted in the rail, the left surface  204 , the right surface  206 , the bottom surface  208 , and the chamfers  210   a  and  210   b  abut corresponding surfaces in a slot at the bottom of the firearm rail, as discussed in more detail below in connection with  FIG. 12 . The chamfers  210   a  and  210   b  avoid sharp angles that may cause damage to either the firearm rail or the bottom weight  116  when the bottom weight  116  is inserted in the rail. In one example embodiment, when fully inserted in the rail, the section of the elongate member  200  between the front end  202  and the chamfers  210   a  and  210   b  protrudes beyond the front end of the rail. In addition, when fully inserted in the rail, the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e  align with corresponding holes in the bottom of the rail, such that screws or other suitable fastening means can be inserted through the bottom of the rail and into the bottom weight to secure the bottom weight  116  to the bottom of the rail. In example alternative embodiments, the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e  are not threaded and can receive alternative fasteners such as pins or pegs. In further alternative embodiments, the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e  can be replaced with protrusions that function as the male aspect of a male-female connection with corresponding female aspects of the firearm rail. 
         [0046]    The cutout  214  at the front end  202  of the bottom weight  116  accommodates the front sling loop  120 . More specifically, the pin hole  216 , which extends through both sides of the cutout  214  houses a pin  220 . Between the two sides of the cutout  214 , the pin  220  also extends through the sleeve  218  of the front sling loop  120 . In this manner, the pin  220  couples the bottom weight  116  to the front sling loop  120  in a pivotable fashion, allowing the front sling loop  120  to pivot around the pin  220 . By pivoting the front sling loop  120 , a firearm user can adjust the sling attached to the front sling loop  120  without adjusting the firearm. In one example embodiment, the pin  220  consists of two protrusions that are integrally cast or machined to both open ends of the sleeve  218  such that the protrusions mate with the pin hole  216  on both sides of the cutout  214 . In another example embodiment, the pin  220  is a discrete component that can be inserted through the pin hole  216  and the sleeve  218 . 
         [0047]    Coupling the front sling loop  120  to the bottom weight  116  avoids the need to attach a sling loop to a firearm rail itself. Attaching a sling loop to a rail can require a bulky connection platform that juts out from the side of the firearm rail and mates on one side with the bottom of the rail and on the other side with the sling loop. Thus, coupling the front sling loop  120  to the bottom weight  116  can provide a firearm with smaller and more discreet profile, fewer accessories that may tend to interfere with operation or transport of the firearm, and/or precise positioning of the sling loop for shooting competitions. 
         [0048]    As discussed above, the bottom weight  116  provides weight to a firearm and firearm rail, as well as strength and stability to a firearm rail. The mass M 1  of bottom weight  116  can be of a variety of values. In some embodiments, M 1  is in a range from about 100 g to about 400 g. In one example, M 1  is about 220 g. M 1  can also fall outside of this range. The elongate member  200  of the bottom weight  116  is also adjustable in length and thereby adjustable in weight. For example the elongate member  200  can be shortened by chopping off (e.g., with a hacksaw) a portion between the screw hole  212   e  and the rear end  201 ; or a section between the screw hole  212   d  and the rear end  201 ; or a section between the screw hole  212   c  and the rear end  201 ; or a section between the screw hole  212   b  and the rear end  201 ; or a section in the middle of the elongate member  200 , leaving portions of the weight on either side. Installing a shortened bottom weight in a firearm rail or multiple segments of a shortened bottom weight in this manner allows for variation in weight and weight distribution of the firearm rail and overall firearm according the user&#39;s desires and specifications. 
         [0049]    As discussed below in more detail in connection with  FIG. 9 , in one example embodiment of the bottom weight  116 , the screw holes  212   a  and  212   b  are positioned on the elongate member  200  such that, when installed in a firearm rail that is itself secured to a firearm, the front sling loop  120  is properly positioned for a firearm shooting competition. 
         [0050]      FIG. 7  is a front, top perspective view of an example side weight for a firearm rail in accordance with the present disclosure;  FIG. 8  is a rear, bottom, perspective view of the side weight of  FIG. 7 .  FIGS. 7 and 8  show the example side weight  114  having the interiorly facing curved surface  192 , as discussed above. The side weight  114  can equivalently correspond to either side weight  114   a  or  114   b  discussed above in connection with  FIGS. 1-4 . Likewise, the interiorly facing curved surface  192  equivalently corresponds to either interiorly facing curved surface  192   a  or  192   b  discussed above in connection with  FIG. 4 . In addition, in this example, the side weight  114  includes an elongate member  230 , a front end  232 , a rear end  234 , a top  236 , a bottom  238 , an arcuate portion  240  having a bottom surface  241 , a flange  242  having a bottom surface  243 , side surfaces  244   a  and  244   b  and chamfers  246   a  and  246   b , holes  248 , and threaded rings  250 . 
         [0051]    The elongate member  230  of the example side weight  114  is configured to be inserted into and housed in a slot at the side of a firearm rail. In some embodiments, the elongate member  230  is made from a relatively dense material to provide weight and strength to the firearm rail in which it is housed and to which it is secured, as well as to provide weight to the overall firearm. 
         [0052]    The example side weight  114  is symmetrical, such that the side weight  114  can be equivalently inserted into a rail from its front end  232  or its rear end  234  first. In one example embodiment, when fully inserted in the rail, the front end  232  (or the rear end  234 ) of the side weight  114  is flush with the front of the rail (such as the rail  112  in  FIG. 3 ). In addition, when fully inserted in the rail, the bottom surface  241  of the arcuate portion  240 , and the bottom surface  243 , side surfaces  244   a  and  244   b , and the chamfers  246   a  and  246   b  of the flange  242  abut corresponding surfaces in a slot at the side of the firearm rail, as discussed in more detail below in connection with  FIG. 12 . The chamfers  246   a  and  246   b  avoid sharp angles that may cause damage to either the firearm rail or the side weight  114  when the side weight  114  is inserted in the rail. In one example embodiment, when fully inserted in the rail, the holes  248  align with corresponding holes in the side of the rail, such that screws or other suitable fastening means can be inserted through the side of the rail and into the side weight to secure the side weight  114  to the side of the rail. In this example, the threaded rings  250  are in open contact with the holes  248  respectively. The threaded rings  250  provide a female counterpart for screws inserted through the rail and the side weight  114  used for securing the side weight  114  to the rail. In one example the threaded rings  250  are made of metal such as steel that does not shear or erode when the screws are threaded therein. This prevents the holes  248  from shearing or eroding from threading screws therein, particularly if the elongate member  230  of side weight  114  consists of a malleable or erodible material such as lead. In example alternative embodiments, there are no threaded rings and the holes  248  can receive alternative fasteners such as pins or pegs. In further alternative embodiments, the holes  248  can be replaced with protrusions that function as the male aspect of a male-female connection with corresponding female aspects of the firearm rail. 
         [0053]    The example side weight  114  is cast or otherwise shaped from metal or a metal alloy, such as lead. In alternative examples, other suitably heavy, strong and rigid materials may be used for the side weight  114 . In one example embodiment of the side weight, all features of the side weight are cast together in a single mold. In alternative embodiments, one or more features of the side weight  114  are machined following the casting process, such as the chamfers  246   a  and  246   b , the holes  248 , and the threaded rings  250 . In further alternative examples, the threaded rings  250  constitute a different material than the rest of side weight  114  as discussed below, and are cast separately and installed in the holes  248 , respectively, after the elongate member  230  and has been cast. 
         [0054]    As discussed above, the side weight  114  provides weight to a firearm and firearm rail, as well as strength and stability to a firearm rail. The mass M 2  of the side weight  114  can be a variety of suitable values. In some embodiments, M 2  is in a range from about 100 g to about 800 g. In one example, M 2  is about 424 g. M 2  can also fall outside of this range. The elongate member  230  of the side weight  114  is also adjustable in length and thereby adjustable in weight. For example, the elongate member  200  can be shortened by chopping off (e.g., with a hacksaw) a portion between any one of the holes  248  and the front end  232 ; or a section in the middle of elongate member  200 , leaving portions of the weight on either side. Installing one or more shortened side weights or multiple segments of one or more shortened side weights in a firearm rail in this manner allows for variation in weight and weight distribution of the firearm rail and overall firearm according the user&#39;s desires and specifications. For example, two side weights of different lengths, or two side weights of equally shortened lengths, can be installed in the same rail to vary the firearm&#39;s weight and weight distribution. 
         [0055]      FIG. 9  is a bottom view of a combination of the example bottom weight for a firearm rail and a sling loop of  FIG. 5 . The example bottom weight  116  includes the elongate member  200 , the rear end  201 , the front end  202 , the bottom surface  208 , the chamfers  210   a  and  210   b , the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e , and the cutout  214 , as discussed above. The front sling loop  120  is also shown in  FIG. 9 , as discussed above. 
         [0056]    The elongate member  200  has a length L 1  as measured between the front end  202  and the rear end  201 . L 1  can be a variety of suitable lengths. In some examples, L 1  is in a range from about 25 mm to about 400 mm. In one example embodiment, L 1  is about 265 mm. Cutout  214  has a length L 2  as measured between the front end  202  of bottom weight  116  and chamfers  210   a  and  201   b . L 2  can be a variety of suitable lengths. In some examples, L 2  is in a range from about 3 mm to about 50 mm. In one example embodiment, L 2  is about 10 mm. In an alternative embodiment, bottom weight  116  does not have a cutout, and the front sling loop  120  is attached to the firearm by another suitable means. 
         [0057]    The example elongate member  200  has a width W 1 . W 1  can be a variety of suitable lengths. In some examples W 1  is in a range from about 5 mm to about 25 mm. In one example embodiment, W 1  is about 12 mm. 
         [0058]    The screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e  can be distributed along the elongate member  200  to match up with corresponding holes in a firearm rail for securing the bottom weight  116  to the firearm rail. 
         [0059]    In the example combination of the bottom weight  116  and the front sling loop  120 , there is a distance D 1  as measured between the rearmost point of the front sling loop  120  and the front most point of the screw hole  212   a . D 1  can be in a variety of suitable lengths. In some examples, D 1  is in a range from 0 mm to about 40 mm. In one example embodiment, D 1  is about 17 mm. In the example bottom weight  116  there is also a distance D 2  between corresponding locations on screw hole  212   a  and the screw hole  212   b  along the bottom surface  208 . D 2  can be a variety of suitable lengths. In some examples, D 2  is in a range from about 5 mm to about 40 mm. In one example embodiment, D 2  is about 20 mm. In some embodiments, D 1  and D 2  are such that, upon installation of the bottom weight  116 , or any portion thereof that includes at a least screw hole  212   a , the front sling loop  120  is disposed in a position relative to the firearm that is suitable for shooting competitions, as discussed above. 
         [0060]    The distance D 3  along the bottom side  208  between corresponding locations on the screw hole  212   b  and the screw hole  212   c  can be a variety of suitable lengths. In some example embodiments, D 3  is in a range from about 5 mm to about 100 mm. In one example, D 3  is about 60 mm. 
         [0061]    The distance D 4  along bottom side  208  between corresponding locations on the screw hole  212   c  and the screw hole  212   d  can be a variety of suitable lengths. In some example embodiments, D 4  is in a range from about 5 mm to about 100 mm. In one example, D 4  is about 70 mm. 
         [0062]    The distance D 5  along bottom side  208  between corresponding locations on the screw hole  212   d  and the screw hole  212   e  can be a variety of suitable lengths. In some example embodiments, D 5  is in a range from about 5 mm to about 100 mm. In one example, D 5  is about 70 mm. 
         [0063]    The distance D 6  along the bottom side  208  between the rearmost point of the screw hole  212   e  and the rear end  201  of the elongate member  200  can be a variety of suitable lengths. In some example embodiments, D 6  is in a range from about 1 mm to about 40 mm. In one example, D 6  is about 18 mm. 
         [0064]      FIG. 10  is a bottom view of the example side weight  114  of  FIG. 7 ;  FIG. 11  is a front view of the example side weight  114  of  FIG. 7 .  FIGS. 10 and 11  show the example side weight  114  having the interiorly facing curved surface  192 , the elongate member  230 , the front end  232 , the rear end  234 , the top  236 , the bottom  238 , the arcuate portion  240  having a bottom surface  241 , the flange  242  having a bottom surface  243 , the side surfaces  244   a  and  244   b  and the holes  248 , as discussed above. 
         [0065]    The example elongate member  230  has a length L 3  as measured between the front end  232  and the rear end  234 . L 3  can be a variety of suitable lengths. In some examples, L 3  is in a range from about 25 mm to about 400 mm. In one example embodiment, L 3  is about 254 mm. 
         [0066]    The arcuate portion  240  has a width W 2 . W 2  can be a variety of suitable widths. In some examples, W 2  is in a range from about 15 mm to about 40 mm. In one example embodiment, W 2  is about 28 mm. The arcuate portion  240  has a height H 1 . H 1  can be any suitable height. In some examples, H 1  is in a range from about 2 mm to about 20 mm. In one example embodiment, H 1  is about 8 mm. The flange  242  has a width W 3 . W 3  can be a variety of suitable widths. In some examples, W 3  is in a range from about 3 mm to about 20 mm. In one example embodiment, W 3  is about 12 mm. The flange  242  has a height H 2 . H 2  can be a variety of suitable heights. In some examples, H 2  is in a range from about 2 mm to about 15 mm. In one example embodiment, H 2  is about 6 mm. In some examples the sum of H 1 +H 2  corresponds to the distance between the deepest surface of the side slot  270  (see  FIG. 12 ) of the rail  112  (see  FIG. 12 ) and the exterior surface of a barrel (e.g., the barrel  106  of  FIG. 1 ) that has been inserted in the rail. 
         [0067]    The holes  248  can be distributed along the elongate member  230  to match up with corresponding holes in a firearm rail for securing the side weight  114  to the firearm rail. In some example embodiments, the holes  248  are evenly spaced along the elongate member  230 . In some example embodiments, the distance D 7  between corresponding locations on each pair of adjacent holes of the holes  248  is in a range from about 5 mm to about 300 mm. In one example, the holes  248  are evenly spaced and D 7  is about 69 mm. 
         [0068]      FIG. 12  is an exploded view of a firearm rail  112  in combination with a barrel nut and example side weights and bottom weight with sling loop in accordance with the present disclosure, illustrating how the barrel nut and weights are installed in the firearm rail. The firearm rail  112  includes the top side  130 , the bottom side  132 , the left side  134 , the right side  136 , the heat vents  138 , the interior surface  140 , the interior bore  141 , the rear end  142 , the front end  144 , the side weight fasteners  180 , the barrel nut fasteners  182 , and the upper channel  190  as discussed above. The bottom weight  116  includes the top surface  194 , the elongate member  200 , the rear end  201 , the front end  202 , the bottom surface  208 , the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e , the cutout  214 , and the pin hole  216 , as discussed above. The front sling loop  120  includes the sleeve  218 , and the pin  220 , as discussed above. The side weights  114   a  and  114   b  include, respectively, the interiorly facing curved surfaces  192   a  and  192   b , the elongate members  230   a  and  230   b , the front ends  232   a  and  232   b , the rear ends  234   a  and  234   b , the arcuate portions  240   a  and  240   b , the flanges  242   a  and  242   b , the side surfaces  244   a  and  244   b  and the holes  248   a  and  248   b , as discussed above. With respect to the side weights  114   a  and  114   b , all numbered features described above in connection with  FIGS. 7-8  correspond to the same reference numbers in  FIG. 12 , but with the added descriptor “a” or “b” to differentiate between the right and left side weights  114   a  and  114   b , respectively. In addition, in this example a barrel nut  260  is shown having grooves  262 . In addition, in this example the barrel nut fasteners  182  include bolts  264 , washers  266  and nuts  268 . In addition, in this example the rail  112  includes longitudinally extending side slots  270   a  and  270   b , a longitudinally extending bottom slot  272 , additional side weight fasteners  274 , bottom weight fasteners  276 , and holes  278 . 
         [0069]    In some example combinations, the firearm parts shown in  FIG. 12  are assembled as follows. The barrel nut  260  is inserted into the rear end  142  of the rail  112 . The barrel nut fasteners  182  are installed by inserting the bolts  264  first through the washers  266  and then through the rail  112 . As the bolts  264  pass through the rail  112 , they engage the grooves  262  of the barrel nut  260 , firmly securing the barrel nut  260  relative to the rail  112 . When the ends of the bolts  264  exit the rail at the opposing side, they are mated with the nuts  268  to secure the bolts in place. 
         [0070]    The side weight  114   a  is installed by inserting the elongate member  230   a  into the side slot  270   a  in the rail  112  until front end  232   a  of the side weight  114   a  is flush with the front end  144  of the rail  112 ; and such that the interiorly facing curved surface  192   a  faces the interior bore  141  of the rail  112 ; and such that the arcuate portion  240   a  hugs the interior surface  140  of the rail  112 ; and such that the flange  242   a  engages the side slot  270   a . Additional side weight fasteners  274  (which are equivalent to side weight fasteners  180 ) are inserted through holes in the right side  136  of rail  112 , and then inserted through holes  248   a  in the side weight  114   a , respectively, to secure the side weight  114   a  to the rail  112 . 
         [0071]    Similarly, the side weight  114   b  is installed by inserting the elongate member  230   b  into the side slot  270   b  in the rail  112  until the front end  232   b  of the side weight  114   b  is flush with the front end  144  of the rail  112 ; and such that the interiorly facing curved surface  192   b  faces the interior bore  141  of the rail  112 ; and such that the arcuate portion  240   b  hugs the interior surface  140  of the rail  112 ; and such that the flange  242   b  engages the side slot  270   b . The side weight fasteners  180  are inserted through the holes  278  in the left side  134  of the rail  112 , and then inserted through the holes  248   b  in the side weight  114   b , respectively, to secure the side weight  114   b  to the rail  112 . 
         [0072]    The bottom weight  116  is installed by inserting the rear end  201  of the elongate member  200  into the bottom slot  272  of the rail  112  such that each of the screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e  aligns with a corresponding hole in the bottom side  132  of the rail  112 ; such that the elongate member  200  engages the bottom slot  272 ; and such that the cutout  214  extends beyond the front end  144  of the rail  212 . The bottom weight fasteners  276  are inserted through holes in the bottom side  132  of the rail  112 , and then inserted in screw holes  212   a ,  212   b ,  212   c ,  212   d , and  212   e , respectively, to secure the bottom weight  116  to the rail  112 . Either before or after the bottom weight  116  is inserted and/or secured to the rail  112 , the sleeve  218  of the front sling loop  120  can be coupled to the pin  220 , which is in turn coupled to the pin hole  216  in the cutout  214 , as discussed above. 
         [0073]    The bottom weight  116  and the side weights  114   a  and  114   b  can be removed (and optionally reinstalled) from the rail  112  by removing the various fasteners securing them to the rail, and extracting the weights from the rail. 
         [0074]    The various embodiments described above are provided by way of illustration only and should not be construed to limit the claims attached hereto. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the following claims.