Abstract:
The present disclosure relates to a firearm support, comprising a main body assembly, at least two legs operably attached to the main body assembly, a mounting assembly comprising an attachment mechanism configured to enable attachment of a firearm to the mounting assembly and a swivel mechanism configured to control an angular rotation about a swivel axis; and a cant mechanism configured to control an angular rotation about a cant axis by rotating the mounting assembly along an opening in the main body assembly, whereby cant angle may be locked and remain constant as an attached firearm swivels.

Description:
FIELD OF THE INVENTION 
       [0001]    This disclosure relates to firearm supports, and, more particularly, to bipods enabling independent cant and swivel adjustments and level measurement capabilities. 
       BACKGROUND OF THE INVENTION 
       [0002]    In a typical mid to long range shooting application, a firearm may be equipped with an optical sighting device (i.e. a sight or scope) mounted above the rifle&#39;s bore. 
         [0003]    To reach long distance targets, elevation compensation is used to counteract the gravitational pull of the Earth on a projectile. As depicted in  FIG. 1A , the bore axis is aimed at a point above the intended target, causing the bullet trajectory to cross the line of sight to the target a first time as the bullet is in an upwards flight path and a second time as it is descending, being pulled by gravity. The angle between the bore axis and the line of sight used to reach distant targets is referred to as the holdover angle (hereinafter β). 
         [0004]    Before proceeding, it is worth noting that when a scope is mounted on a rifle it is almost always mounted parallel to the bore of the firearm, however, in  FIG. 1A , an angle between the scope and the rifle barrel is depicted to better illustrate the problem encountered. In reality, the angle between the bore and point of aim is typically created within the scope optics, which allow for elevation adjustment. The elevation correction within the scope points the line of sight downward, which in turn points the bore axis up when the sight is aligned with the target. 
         [0005]    In regards to determining the correct holdover angle β, the holdover angle β is determined through a two-step process. The first step is to set the holdover angle β so that the bullet trajectory intersects the line of sight at a specific distance (100 yards for instance). When the holdover angle is so adjusted, the rifle bore and sight are said to be “zeroed” for that distance. 
         [0006]    The second step is only necessary if the target is not at the zeroed distance. This step requires the rifleman to use a table, which is often referred to as a “drop table,” to determine the final adjustment to the holdover angle β. A typical drop table lists the height of a bullet above or below the line of sight as a function of the distance to the target. A drop table may be generated empirically at a rifle range; calculated using a ballistic simulator; or provided by ammunition manufacturers. Drop values are calculated under the assumption that the rifle has been zeroed at a specific distance at which the drop value is zero. Even for the same firearm, drop tables are specific to several parameters including bullet weight, bullet shape, cartridge powder load, primer used, barrel length, wind speed, direction and other variables. 
         [0007]    Problematically, these adjustments and calculations assume that the rifle is held perfectly vertical. A significant problem is induced if a rifle is fired when the rifle plane, which is the plane that includes the line of sight and the bore axis, is not in the vertical plane, defined as the plane including the line of sight and a line from the center of the earth to the end of the rifle&#39;s bore. The angle between the rifle plane and vertical planes is referred to as the cant angle; when the cant angle (α) is not zero: this is called cant error. Since a shooter&#39;s eye is the point of reference, when the rifle plane is not in the vertical plane i.e. when a rifle is held canted, the rifle&#39;s bore rotates around the line of sight while the relationship between the sighting device and the barrel does not change. 
         [0008]    Cant modifies the impact point of a projectile, creating a windage error Δx (horizontal component) and an elevation error Δy (vertical component). In the example depicted in  FIG. 1B , the impact point of the canted trajectory shifts the impact point low and left of the vertical-hold trajectory. This is because any amount of cant will cause some of the holdover angle β to instead alter the trajectory left or right of the target, depending on which way the rifle is canted, both sending the projectile off-center and preventing it from reaching the intended apex of its vertical trajectory. 
         [0009]    As a first approximation, the windage, or horizontal, error (Δx) is directly proportional to the distance to the target, to α and to β. The windage error Δx is approximately 3 cm per degree of α per degree of β and per 100 m of distance to the target. For example, at  500   m , with β=0.2 degrees (typical of a high-velocity 5.56 mm bullet at that distance) Δx is approximately 3 cm per degree of cant. 
         [0010]    This numerical example shows that at long range, even small deviations from a vertical hold significantly affect the impact point of a projectile. This windage error is subject to a compound effect when the distance to the target increases or when using a lower velocity round, as β itself increases with increasing distance and lower projectile velocity, since greater elevation compensation is needed in both situations to account for the longer period on which gravity will act on the projectile prior to impact with the target. 
         [0011]    The windage error becomes an order of magnitude larger when shooting at an elevated target. With the previous example, at 500 m, shooting at a target just 2 degrees above the shooter, a single degree of cant induces a windage error Δx of approximately 30 cm. 
         [0012]    Another issue faced by long-distance riflemen is that, in real life situations, there is typically no reference to the true horizon. If the shooter is on uneven ground and/or is aiming towards a non-horizontal background, the human physiology is not able to determine the position of the vertical plane with any degree of precision and significant unintentional canting of the rifle is to be expected. 
         [0013]    Furthermore, when it is a shooter&#39;s intent to track a moving target, the shooter would, ideally, in a first step adjust the cant angle to adapt to the conditions of the terrain where the bipod is standing and in a second step allow the rifle to swivel to track the target. Such swivel/tracking functionality would ideally be such that it does not induce cant error when used. 
         [0014]    Classic bipods do not allow for cant angle adjustment, their legs are either in a stored or deployed orientation. Often, such legs are telescopic. Other bipods offer only cant adjustment. 
         [0015]    There are, however, bipods available that offer adjustment of cant and swivel angles, however, these angles may not be adjusted independently in the majority of such designs. Typical designs include a ball and socket joint whereby cant and swivel are adjusted simultaneously. This means that if a shooter attempts to track a target (swiveling) it is likely that the cant angle will be simultaneously modified. 
         [0016]    Still other designs allow for cant and swivel angles to be independently adjusted. In such designs, however, once the cant angle has been adjusted, subsequent use of the swiveling functionality will modify the cant angle if the legs are not in the horizontal position, inducing cant error. Furthermore the cant adjustment mechanism of such designs relies on an unstable equilibrium concept: if loosened, gravity will cause the firearm being supported to tilt or fall to the side. A different design with a stable equilibrium would allow the mechanism to tend towards the vertical position on its own, stay there without requiring the user to exert strong force until the cant position is secured, and make it significantly easier to make one handed cant adjustments, even in prone position. 
         [0017]    What is needed, therefore, are techniques for enabling a user to readily determine if a rifle is canted and to set a cant angle while allowing for swiveling and target tracking without impacting cant angle adjustment. 
       SUMMARY OF THE INVENTION 
       [0018]    It is an object of the present invention to provide a mechanism for tracking/swiveling movement without changing the cant angle. 
         [0019]    It is another object of the present invention to provide a means of determining the cant angle, specifically in a way that is visible by the operator while adjusting the cant angle. 
         [0020]    One embodiment of the present invention provides a firearm support, comprising: a main body assembly, at least two legs operably attached to the main body assembly, a mounting assembly comprising an attachment mechanism configured to enable attachment of a firearm to the mounting assembly, a cant guide projection comprising two concentric surfaces, and a swivel mechanism configured to control an angular rotation about a swivel axis, and a cant mechanism configured to control an angular rotation about a cant axis by rotating the mounting assembly along an opening in the main body assembly comprising two concentric surfaces co-concentric with the cant guide projection concentric surfaces. 
         [0021]    Another embodiment of the present invention provides such a firearm support wherein the at least two legs are each operably attached to the main body assembly by an indexer assembly configured to control an angular rotation of the at least two legs about the main body assembly. 
         [0022]    A further embodiment of the present invention provides such a firearm support wherein the at least two legs each comprise a telescoping assembly operable to extend and retract the at least two legs. 
         [0023]    Yet another embodiment of the present invention provides such a firearm support wherein each telescoping assembly further comprises a catch channel disposed on the inner leg and a catch screw extending through the outer leg and operable to engage the catch channel. 
         [0024]    A yet further embodiment of the present invention provides such a firearm support further comprising a cant locking mechanism comprising a locking plate and a threaded element such as a thumb screw or a locking lever operable to clamp the main body between the locking plate and the threaded element. 
         [0025]    Still another embodiment of the present invention provides such a firearm support wherein the locking plate includes a level indicator. 
         [0026]    A still further embodiment of the present invention provides such a firearm support wherein the threaded element is captive. 
         [0027]    Even another embodiment of the present invention provides such a firearm support wherein the swivel mechanism comprises a first plate that stays fixed in relation to the firearm, a second plate configured to rotate parallel to the first plate around the swivel axis and a swivel locking assembly configured to move between a swivel locked position and a swivel unlocked position. 
         [0028]    An even further embodiment of the present invention provides such a firearm support wherein the swivel mechanism comprises a means to limit the angular rotation of the second plate around the swivel axis. 
         [0029]    A still even another embodiment of the present invention provides such a firearm support wherein the attachment mechanism comprises a mounting base having a rail-engaging clamp member and at least one locking lever being mounted to the mount base and being moveable to a clamping position, whereby clamping engagement with the mount rail is established, and to a released position, whereby clamping engagement with the mount rail is released. 
         [0030]    A still even further embodiment of the present invention provides such a firearm support wherein each of the at least two legs further comprises a removable support foot attached to the outer leg. 
         [0031]    One embodiment of the present invention provides a firearm support comprising a main body assembly, two legs operably attached to the main body assembly, a mounting assembly, a cant mechanism operable to control an angular rotation about a cant axis and to lock the position of the mounting assembly in a desired position relative to the ground and a swivel mechanism operable to control an angular rotation about a swivel axis, wherein the swivel mechanism can always be operated in such a way that the swivel axis remains perpendicular to the cant axis as the firearm swivels. 
         [0032]    One embodiment of the present invention provides a firearm support comprising a cant mechanism operable to control an angular rotation about a cant axis and a swivel mechanism operable to control an angular rotation about a swivel axis, wherein the cant axis is substantially concentric with a bore of a firearm to which the firearm support is attached. 
         [0033]    One embodiment of the present invention provides a firearm support comprising a cant mechanism operable to control an angular rotation about a cant axis and a swivel mechanism operable to control an angular rotation about a swivel axis, wherein the cant mechanism is located below the swivel mechanism. 
         [0034]    One embodiment of the present invention provides a firearm support comprising a main body assembly, a mounting assembly, wherein the mounting assembly comprises an attachment mechanism operable to attach a firearm to the mounting assembly, a cant mechanism operable to control an angular rotation about a second axis, wherein the cant mechanism is created by rotating the mounting assembly along an opening in the main body assembly, whereby swivel and cant may be adjusted independently, and at least two legs operably attached to the main body assembly; wherein the at least two legs are each operably attached to the main body assembly by an indexer assembly configured to control an angular rotation of the at least two legs about the main body assembly; and wherein each indexer assembly comprises a spring loaded button that allows the leg to be released from its indexed position, and wherein the button can be pushed to release the indexed position. 
         [0035]    One embodiment of the present invention provides a firearm support comprising a main body assembly, at least two legs operably attached to the main body assembly; wherein the at least two legs each comprise a telescoping assembly operable to extend and retract the at least two legs, and wherein each telescoping assembly comprises an outer leg further comprising an opening that is perpendicular to the outer leg axis, an inner leg at least partially disposed within the outer leg and operable to extend and retract relative to the outer leg, and comprising a plurality of notches disposed about the inner leg and a spring loaded release button disposed around the inner leg, wherein the release button only protrudes from the outer leg, if at all, through the outer leg opening; and wherein the release button is operable to slide within at least one of the plurality of notches so as to block the movement of the outer leg in relation to the inner leg, or when depressed to slide out of the notches so as to allow the outer leg to extend and retract relative to the inner leg. 
         [0036]    Another embodiment of the present invention provides such a firearm support wherein the release button does not protrude from the outer leg. 
         [0037]    A further embodiment of the present invention provides such a firearm support wherein each of the at least two legs further comprises a removable support foot attached to the outer leg. 
         [0038]    Yet another embodiment of the present invention provides such a firearm support wherein each of the removable support foot is contained in the cylinder defined by the outer leg envelope. 
         [0039]    One embodiment of the present invention provides a firearm support comprising a main body assembly, at least two legs operably attached to the main body assembly, a cant mechanism operable to control an angular rotation about a cant axis and a level indicator. 
         [0040]    Another embodiment of the present invention provides such a firearm support wherein the level indicator comprises a ball guided in a cavity filled with a liquid. 
         [0041]    A further embodiment of the present invention provides such a firearm support wherein the ball is guided between at least two surfaces, two of which are concentric with the cant axis. 
         [0042]    Yet another embodiment of the present invention provides such a firearm support further comprising a swivel mechanism operable to control an angular rotation about a swivel axis. 
         [0043]    One embodiment of the present invention provides a method for adjusting the cant and swivel of a bipod mounted device when tracking a target comprising providing a bipod mounting assembly comprising: first and second extendable legs; the bipod mounting assembly including a cant control mechanism controlled using a first control knob; the bipod mounting assembly further comprising a swivel control mechanism controlled using a second control knob, the swivel control mechanism being independent of the cant control mechanism; grasping the bipod mounted device and placing the first and second extendable legs against a supporting surface; aiming the bipod mounted device to orient the bipod mounting assembly at a selected cant angle or angle relative to a vertical plane, preferably in the vertical plane, and locking such cant angle using the first control knob; unlocking the swivel control mechanism using the second control knob; and aiming the bipod mounted device at the target. 
         [0044]    The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]      FIG. 1A  illustrates bore axis, line of sight and bullet trajectory; 
           [0046]      FIG. 1B  illustrates the point of impact for a vertical hold trajectory and for a canted trajectory. In this rear view, a sighting device is depicted as well as a rifle bore, both in a vertical hold position and in a canted position; 
           [0047]      FIG. 2  is a front, top, left-side perspective view of a first bipod in accordance with embodiments of the present disclosure; 
           [0048]      FIG. 3  is a partial front, top, left-side perspective view of the first bipod presented in this disclosure which identifies the cant axis and the swivel axis; 
           [0049]      FIG. 4A  is a front, top, left-side perspective view of a bipod main body assembly in accordance with embodiments of the present disclosure; 
           [0050]      FIG. 4B  is a front, top, left-side perspective view of a first embodiment of the mounting assembly showing a quick disconnect rail attachment in accordance with embodiments of the present disclosure; 
           [0051]      FIG. 5A  is a front, top, right-side exploded perspective view of a swivel and swivel lock mechanisms in accordance with embodiments of the present disclosure; 
           [0052]      FIG. 5B  is a rear, bottom, left-side perspective view of a swivel and swivel lock mechanisms of the mounting assembly of  FIG. 5A ; 
           [0053]      FIG. 6A  is a front, top, left-side perspective view of a mounting assembly with a “permanent” clamping rail attachment mechanism, shown with a mounting rail, in accordance with embodiments of the present disclosure; 
           [0054]      FIG. 6B  is a front, top, left-side exploded perspective exploded view of the mounting assembly of  FIG. 6A ; 
           [0055]      FIG. 6C  is a rear, bottom, right-side, exploded perspective exploded view of the mounting assembly of  FIG. 6A ; 
           [0056]      FIG. 7A  is a section view showing details of a swivel mechanism, a swivel lock mechanism, a cant lock mechanism and a captive retention mechanism of a cant lock thumb screw where the cant angle is locked and the swivel function is locked, in accordance with embodiments of the present disclosure; 
           [0057]      FIG. 7B  is a section view showing details of a swivel mechanism, a swivel lock mechanism, a cant lock mechanism and a captive retention mechanism of a cant lock thumb screw where the cant angle is unlocked and the swivel function is unlocked, in accordance with embodiments of the present disclosure; 
           [0058]      FIG. 8A  is a perspective cross sectional view of a leg rotation and indexing mechanism, in accordance with embodiments of the present disclosure; 
           [0059]      FIG. 8B  is an exploded perspective view of a leg rotation and indexing mechanism, in accordance with embodiments of the present disclosure; 
           [0060]      FIG. 9  is an exploded view of a leg extension mechanism, in accordance with embodiments of the present disclosure; 
           [0061]      FIG. 10  is a perspective view of two embodiments of a leg extension knob, in accordance with embodiments of the present disclosure; 
           [0062]      FIG. 11A  is a perspective view of a leg assembly, wherein a leg extension knob is depressed, enabling an outer leg to slide in relation to an inner leg, in accordance with embodiments of the present disclosure; 
           [0063]      FIG. 11AA  is a top view of the embodiment of the leg extension knob of  FIG. 11A , wherein the leg extension knob is depressed, enabling the outer leg to slide in relation to the inner leg in accordance with embodiments of the present disclosure; 
           [0064]      FIG. 11B  is a perspective view of a leg assembly, wherein a leg extension knob is not depressed, and, consequently, is in engagement with inner leg notches, preventing movement of an outer leg, in accordance with embodiments of the present disclosure; 
           [0065]      FIG. 11BB  is a top view of the embodiment of the leg extension knob of  FIG. 11B , wherein the leg extension knob is not depressed, and, consequently, is in engagement with inner leg notches, preventing movement of an outer leg, in accordance with embodiments of the present disclosure; 
           [0066]      FIG. 12  is a perspective view of a leg assembly with a foot and a leg extension knob both fitting within the envelope of the outer leg, in accordance with embodiments of the present disclosure; 
           [0067]      FIG. 13  is a rear elevation view of a leg with an angled foot and another leg with a straight foot, in accordance with embodiments of the present disclosure; 
           [0068]      FIG. 14A  is a rear, bottom, right-side perspective view of a mounting assembly with a level indictor, in accordance with embodiments of the present disclosure; 
           [0069]      FIG. 14B  is a front, top, left-side perspective view of a mounting assembly with a level indicator, in accordance with embodiments of the present disclosure; 
           [0070]      FIG. 15A  is a front, top, left-side, exploded perspective view of a level assembly, in accordance with embodiments of the present disclosure; 
           [0071]      FIG. 15B  is a rear, top, left-side, exploded perspective view of a level assembly, in accordance with embodiments of the present disclosure; and 
           [0072]      FIG. 16  is a rear elevation view of a bipod assembly including a level, in accordance with embodiments of the present invention. 
           [0073]      FIG. 17  is a front, top, left-side perspective view of a second bipod in accordance with embodiments of the present disclosure; 
           [0074]      FIG. 18  is a front, top, left-side perspective view of the mounting assembly and main body assembly of the second bipod presented in this disclosure, further identifying the cant axis and the swivel axis; 
           [0075]      FIG. 19A  is a front, top, right-side exploded perspective view of the mounting assembly and main body assembly of  FIG. 18 ; 
           [0076]      FIG. 19B  is a rear, bottom, left-side perspective view of the mounting assembly and main body assembly of  FIG. 18 ; 
       
    
    
     DETAILED DESCRIPTION 
       [0077]    For a rifle equipped with a sighting device we define:
       The bore axis as the axis of the rifle&#39;s bore;   The line of sight as the straight line from the reticle of the sighting device to the target;   The holdover angle β as the angle between the bore axis and the line of sight;   The rifle plane as the plane including the line of sight and the bore axis;   The vertical plane as the plane including the line of sight and the line from the center of the earth to the end of the rifle&#39;s bore; and   The cant angle α as the angle between the vertical plane and the rifle plane.       
 
         [0084]    The present disclosure provides bipods intended to be mounted to a rail platform, which allow for determining and setting of a cant angle while allowing for the rifle to be swiveled without affecting the cant angle, allowing for accurate target tracking at a long distance. 
         [0085]    The bipods of the present disclosure provide a cant mechanism created by the interaction between a main body assembly  200  and a mounting assembly  100 . 
         [0086]      FIG. 4A  represents a first embodiment of a main body assembly  200 . The main body assembly  200  may include an opening with two concentric surfaces  212  and two angulated leg pivot surfaces  220 . Mounting assembly  100  includes a mounting mechanism to attach mounting assembly  100  to a firearm, for example via a rail  400 . Rail mounting mechanisms will be described below. 
         [0087]      FIG. 4B  represents a first embodiment of mounting assembly  100 , featuring a quick disconnect rail mounting mechanism. 
         [0088]      FIG. 6A  represents a second embodiment of mounting assembly  100 , featuring a permanent rail mounting mechanism. 
         [0089]      FIGS. 14A and 14B  represent a third embodiment of mounting assembly  100 , featuring a cant locking plate  130 L integrating a level indicator. Level indicators will be further discussed below. Mounting assembly  100  also includes a cant guide projection  122  featuring two concentric surfaces  122 A. Concentric surfaces  122 A and concentric surfaces  212  are all concentric with cant axis  1 . The dimensional tolerances of surfaces  122 A and  212  should allow a smooth rotation of mounting assembly  100  in main body assembly  200 . For ease of operation it is desirable that the cant axis  1  be concentric or close to concentric with the rifle bore. 
         [0090]    Now referring to the cant angle lock mechanism with captive thumb screw, as depicted in  FIG. 4B , mounting assembly  100  further includes a clamp surface  125 , a cant locking plate  130  or  130 L and a cant locking thumb screw  140 . 
         [0091]    When the user of such an embodiment has selected a cant angle, such angle, in embodiments, may be locked by clamping main body assembly surfaces  214  between the clamp surface  125  and cant locking plate  130  of mounting assembly  100  using cant locking thumb screw  140 . A cant guide projection  122  may include a non-threaded opening  122 C guiding cant locking thumb screw  140  (See  FIGS. 5B and 6B ). 
         [0092]      FIGS. 7A and 7B  illustrate the cant lock mechanism. In  FIG. 7A , cant locking thumb screw  140  is screwed down, main body assembly  200  is clamped and the cant angle is locked. 
         [0093]    In  FIG. 7B , cant locking thumb screw  140  is unscrewed, main body assembly  200  can rotate around cant axis  1  and the cant angle may be adjusted. 
         [0094]    Cant locking plates  130  and  130 L, in embodiments, have a threaded hole  131 C so as to host a set screw  150  (see  FIGS. 6B, 6C, 7A, 7B, 15A and 15B ). Cant locking thumb screw  140  may also have a recessed area  142 , so that, in conjunction with set screw  150 , thumb screw  140  is prevented from backing out: it is retained. The length of recess  142  may be such that no force is applied to the tip of  140  while threaded section  141  is engaged in threaded section  131 A of  130  or  130 L ( FIG. 7B ). 
         [0095]    Embodiments of the present disclosure may further incorporate a swivel mechanism. Such a mechanism may be a part of mounting assembly  100 . As shown in  FIGS. 5A and 5B , such a mechanism, in embodiments comprises a mounting plate  110 , a swivel plate  120 , a thrust bearing  126  and a swivel plate attachment screw  128 . Mounting plate  110  may further comprise a swivel cylinder cavity  112 , while swivel plate  120  may further comprise a swivel cylinder  123 . Elements  112  and  123 , in embodiments are concentric with swivel axis  2 . Cant guide projection  122 , in embodiments is permanently attached to swivel plate  120 . Thrust bearing  16  is preferable but not strictly necessary. Glue may optionally be applied to screw  128  and allowed to cure during the assembly process to prevent screw  128  from becoming loose. 
         [0096]    The swivel friction force, in embodiments, may be adjusted by varying the torque applied to screw  128 . 
         [0097]    The swivel angle, in embodiments may be limited to a predetermined range, for instance by adding a tab to the inside wall of cylinder  123  and a corresponding recess to cylinder cavity  112  (not shown). Since the swivel angle is limited by interference with main body assembly  200 , a limitation of the swivel range within mounting assembly  100  is not necessary. 
         [0098]    The swivel mechanism is completely independent from the cant mechanism. 
         [0099]    A most important feature of the aforementioned cant angle adjustment mechanism is that once the cant angle is adjusted to zero, mounting assembly  100  is horizontal. Therefore, the swivel mechanism allows for tracking of a target while keeping the firearm in the vertical plane, thus avoiding the creation of cant error. 
         [0100]    It is therefore important and beneficial to have the following mechanical sequence: firearm—mounting mechanism—swivel mechanism—cant mechanism—legs instead of firearm—mounting mechanism—cant mechanism—swivel mechanism—legs. 
         [0101]    Still other embodiments of the present disclosure incorporate a swivel lock assembly. A swivel lock assembly, in embodiments, comprises a swivel locking knob  160 , a swivel lock screw  170 , a swivel lock spring  180  (see  FIGS. 5A and 5B ). A first cavity  113  in mounting plate  110  and a second cavity  124  in swivel plate  120  (see  FIGS. 5A, 5B, 7A, 7B ) allow the swivel lock assembly to slide through swivel plate  120  and into mounting plate  110 . 
         [0102]    The swivel locking knob  160 , in embodiments, has a locking projection  162  that is configured to sink into swivel locking knob cavity  121 . 
         [0103]    In  FIG. 7A  the swivel function is locked: locking projection  162  is in swivel locking knob cavity  121 , swivel lock screw  170  protruded in first cavity  113 : mounting plate  110  cannot rotate in relation to swivel plate  120 . 
         [0104]    In  FIG. 7B  the swivel function is unlocked: Swivel locking knob  160  has been pulled and twisted, locking projection  162  sits above swivel locking knob cavity  121 , swivel lock screw  170  does not protrude in first cavity  113 : mounting plate  110  can rotate in relation to swivel plate  120  around swivel axis  2 . 
         [0105]    Further embodiments of the present disclosure incorporate rail mounting mechanisms, such as quick disconnects and permanent clamps, for mounting the bipod of the present disclosure to a firearm. 
         [0106]    Firearms such as M-16/AR-15/M4 and other long range rifles often feature accessory mounting rails positioned below, above and/or on the sides of the barrel. Such a rail may include a number of mounting projections interleaved with a series of grooves, and these mounting projections and grooves may be employed to associate the accessory with the rail. Rails usually conform to certain standards. For example, two common rails include the “Picatinny” MIL-STD  1913  rail and the “Weaver” rail, both include interleaved mounting projections and grooves, but differ in their dimensions. Other rail types, such as the “keymod” rail exist and one of ordinary skill in the art would be able to readily adapt the invention of the present disclosure to such an alternative rail system. 
         [0107]    Firearm accessories have historically been mounted by means of mounting screws. This is typically referred to as a permanent mount since the accessory will typically remain assembled to the firearm until the end of a mission. Because various missions often require a different set of accessories, and because field modification of weapon configurations can be critical in combat situations, there is a need for versatile and reliable quick-disconnect (QD) attachment mechanisms, also known as “throw lever” mechanisms. We present here two means of attachment to a mounting rail  400  featuring four oppositely angulated clamping surfaces  401 . 
         [0108]      FIGS. 5A and 5B  show a quick disconnect rail attachment mechanism in accordance with embodiments of the present disclosure. This mechanism includes mounting plate  110 , QD lever  190  and QD lever latch  195 . Mounting plate  110  has three clamping surfaces  111 . QD lever  190  may be rotated so as to provide a fourth clamping surface. 
         [0109]      FIG. 4B  shows QD lever  190  in a rail locking position.  FIG. 5A  shows QD lever  190  in unlocked position. It is beyond the scope of this disclosure to detail the QD mechanism inner workings. 
         [0110]      FIG. 6A  shows an alternative embodiment of mounting assembly  100 , with a “permanent” (as defined above) clamping rail attachment mechanism, shown with the mounting rail  400 .  FIGS. 6B  and  6 C are perspective exploded views of the mounting assembly of  FIG. 6A . In this embodiment, the attachment mechanism includes a mounting plate  110 A, a mounting clamp  110 B and a plurality of mounting screws  110 C. Mounting plate  110 A has two rail clamping surfaces  111 A. Mounting clamp  110 B has two rail clamping surfaces  111 B. 
         [0111]    Although rail mounting systems are extensively discussed and have many desirable attributes when used in conjunction with embodiments of the present disclosure, the scope of this disclosure should not be limited to rail mounting solutions. Methods of mounting an accessory to firearms not equipped with such rails are well known to those having ordinary skill in the art. 
         [0112]    Now referring to  FIGS. 8A and 8B , leg rotation and rotation indexing mechanisms in accordance with embodiments of the present disclosure are shown. In embodiments, each of the leg indexing pivot plates  220  have a plurality of indexing notches  222 . Furthermore, each inner leg  310  may comprise a cavity  351  hosting a leg rotation knob  350  and spring  370 . Spring  370  may be configured to continuously push rotation knob  350  outward. Still further, rotation knob  350  may have a slot  354  and an opening  352 . A set screw  360  may ride within slot  354 , to retain rotation knob  350  inside cavity  351  and prevent  350  from rotating. 
         [0113]    In embodiments, a leg may be locked when  350  is positioned in one of the cavities  222  and spring  370  biases  350  outwards, as shown in  FIG. 8A . 
         [0114]    Rotation knob may further comprise an opening  352 . This opening  352 , in embodiments, is configured to allow inner leg  310  to rotate when a user presses on  350 . 
         [0115]    Inner leg  310 , in embodiments, may also comprise a forked end  312 . In such an embodiment, pin  240  is secured into inner leg  310  and goes through a pivot plate  220 , providing an axis of rotation for inner leg  310 . Alternatively, pin  240  could be a screw and a nut. 
         [0116]    Now referring to  FIGS. 9 and 12 , a leg extension and extension indexing mechanism is shown, in accordance with embodiments of the present invention. In such embodiments, each leg assembly  300  may comprise an inner leg  310 , outer leg  320 , set screw  318 , leg extension knob  330 , resilient member (e.g. a wave spring)  340 , foot  380 . Inner leg  310  may further comprise a plurality of extension indexing notches  314  and a slot  316 . In such embodiments, set screw  318  travels in slot  316  and prevents outer leg  320  from completely sliding out of inner leg  310 . 
         [0117]    Now referring to  FIG. 10 , a magnified perspective view of leg extension knob  330  and of a low profile second embodiment thereof is shown. In this embodiment, leg extension knob  330  features two pairs of parallel surfaces. A first pair of surfaces  332  slide along inner leg  310  and prevent the rotation of knob  330  as well as the rotation of outer leg  320  around inner leg  310 . A second pair of surfaces  336  configured to fit within notches  314  and lock the movement of outer log  320  in relation to  310  may also be used in such an embodiment. Resilient member  240  may be used to constantly urge knob  330  outwards. 
         [0118]    Now referring to  FIG. 11BB , a cross section of leg assembly  300  is shown wherein the leg extension movement is blocked. 
         [0119]      FIG. 11AA  shows a cross section of leg assembly  300  wherein knob  330  is depressed, preventing the extension or retraction of outer leg  320  in relation to inner leg  310 . 
         [0120]    Embodiments of the present invention further comprise a level or cant indicator. Such embodiments include a cant guide projection  122 , which includes two guide holes  122 B (see  FIG. 6C ). Cant locking plates  130  and  130 L may also be used, such plates further comprising two orientation pegs  131 B ( FIGS. 6B, 15B ) that mate with the two guide holes  122 B so as to keep the orientation of  130  or  130 L constant in relation to swivel plate  120  and cant guide projection  122 . 
         [0121]      FIGS. 15A and 15B  illustrate a level indicator assembly in accordance with embodiments of the present invention comprising an extended cant locking plate  130 L used as level housing, a level cover  132 , a vial housing  134 , a vial cover  136 , a ball  138 , and a plurality of attachment screws (not shown). Vial housing  134  may be made of transparent material and ball  138  may advantageously be made of heavy material such as steel. 
         [0122]      FIG. 15A  further details a vial housing  134  featuring a ball cavity  134 A filled with a low freezing point, inert liquid such as alcohol (not shown). The radius of curvature of the two concentric surfaces of ball cavity  134 A is selected so as to provide good angular sensitivity. 
         [0123]    In embodiments, vial housing  134  may also feature a track  134 B to house a compression ring (not shown) to prevent the aforementioned liquid from leaking. 
         [0124]    Alternatively, vial housing  134  and vial cover  136  can be replaced by a unitary glass vial. 
         [0125]    In embodiments, vial cover  132  further comprises an opening  132 A so as to allow a user to ascertain the position of ball  138 . Vial cover  132  may also comprise angular markings  132 B, enabling direct reading of the cant angle, preferably with each dot representing 1 degree of cant. 
         [0126]      FIGS. 14A and 14B  represent a third embodiment of mounting assembly  100 , which features the level indicator assembly presented in  FIGS. 15A and 15B . 
         [0127]      FIG. 16  is a back view (view from where the user is standing) of the complete bipod with the level indicator assembly presented in  FIGS. 15A and 15B . It shows how the information necessary to set the cant angle is available to the user right next to the thumb screw  140 , which is the control used to lock the cant angle. 
         [0128]    Further embodiments, as shown in  FIGS. 12 and 13 , may further comprise angled feet for maximized friction and streamlined leg design. These figures show an angled foot  380 . Compared to straight feet such as  380 A commonly available, angled foot  380  allows for a greater contact area with the ground  385 , generating greater friction with a smaller foot diameter. Foot  380 , in embodiments, may be held in place by a pin or a spring plunger (not shown) and is thus removable. 
         [0129]    Combining a low profile leg extension knob  330 A and angled foot  380  allows the device to provide a streamlined leg design, where nothing protrudes from the envelope of the outer leg cylinder. 
         [0130]      FIGS. 18, 19A and 19B  represent a second embodiment of a main body assembly  200  and a fourth embodiment of a mounting assembly  100 . Main body assembly  200  may include two angulated leg pivot surfaces  220 . Main body assembly  200  may include cylindrical surfaces such as those of shoulder screw  250  that act the same way surfaces  212  do in the first three embodiments of main body assembly  200 . Mounting assembly  100  includes a mounting mechanism to attach mounting assembly  100  to a firearm. Mounting assembly  100  may include one or more cant guide projections  122  containing concentric cylindrical surfaces  122 A dimensioned to allow mounting assembly  100  to rotate around shoulder screw  250 . 
         [0131]    The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. Each and every page of this submission, and all contents thereon, however characterized, identified, or numbered, is considered a substantive part of this application for all purposes, irrespective of form or placement within the application. This specification is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure.