CROSS-REFERENCE TO RELATED APPLICATION 
   This Application claims the benefit of U.S. Provisional Application Ser. No. 60/742,243, filed Dec. 4, 2005, which is incorporated herein by reference. 


   FIELD OF THE INVENTION 
   The present invention generally relates to firearms, and specifically to a lightweight bipod for use with machine guns. 
   BACKGROUND OF THE INVENTION 
   Taking a precision shot requires several constants. Among them are the ability of the shooter to acquire the appropriate sight picture, and the ability press the trigger straight to the rear without disturbing the sight picture. The weapon and ammunition should be capable of providing the shooter every advantage to take his best shot. The shooting position has to be stable, but stability is relative depending on the operating conditions. Prone is typically the most stable position, but not everyone&#39;s prone position is the same. Tactical and topographical considerations may also preclude the use of conventional prone positions. Further, urban operations may require a stable position off of a roof, or inside a dwelling. 
   Artificial rests add stability, and may include rucksacks, bean bags and locally acquired debris. The most common and convenient rest is the use of thirty-round magazines that are in the M4 carbines and M16 rifles used by the military. Although it is not optimal on hard surfaces, it is usually present as a necessary supply for the firearms. 
   Existing bipods are typically heavy and contain a multitude of parts. Further, not all of them can quickly traverse and/or cant without the operator adjusting the position of the legs or loosening and retightening parts. Therefore, there is a need for a lightweight, traversing and canting bipod that can be manually adjusted without the use of tools. 
   SUMMARY OF THE INVENTION 
   One embodiment of the invention is a bipod for use with firearms including legs that stow near the firearm body and are easily deployed by rotating and/or extending them away from the firearm. One embodiment of the invention also includes a mounting system that allows the firearm to traverse and or cant. 
   One embodiment has legs that may be individually rotated using a ball lock system. One embodiment is arranged such that the operator presses a plunger and a leg rotates away from the firearm to deploy, or toward the firearm to stow the legs. A ball lock in one embodiment also contains a stop to prevent over rotation. 
   One embodiment has telescoping legs and contains an inner and outer component. The operator pulls on the inner leg to deploy it. One embodiment has a tab and button, which are integral parts of the inner legs, and allow the operator to adjust the height of the bipod as necessary. The button may also assist in holding the inner leg in a fully retracted position. One embodiment has a firearm mounting system, or rail clamp, which allows the firearm to traverse and/or cant without the use of adjustment tools. One embodiment has both a center swivel bolt, thereby allowing traverse movement, and a pivot, thereby allowing canting movement. 
   Other aspects of the invention will be come apparent to those of skill in the art upon reading the following Detailed Description of the Invention and the drawings. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a front perspective view of the bipod in the deployed position. 
       FIG. 1B  is a top perspective view of the bipod in the stored position. 
       FIG. 1C  is a side perspective view of the bipod in the stored position attached to a firearm rail. 
       FIG. 2A  is an exploded view of the bipod. 
       FIG. 2B  is a cross sectional view of the stored bipod across the line  2 B- 2 B in  FIG. 1C . 
       FIG. 2C  is a cross sectional view of the ball lock in a non-depressed state. 
       FIG. 2D  is a cross sectional view of the ball lock in a depressed state. 
       FIG. 2E  is an elevational view of the ball retainer. 
       FIG. 2F  is a cross sectional view of the ball retainer across line  2 F- 2 F of  FIG. 2E . 
       FIG. 2G  is an elevational view of the plunger. 
       FIG. 2H  is a cross sectional view of the plunger across line  2 H- 2 H of  FIG. 2G . 
       FIG. 3A  is a overhead perspective view of the center swivel. 
       FIG. 3B  is a cross-sectional view of the center swivel across line  3 B- 3 B of  FIG. 3A . 
       FIG. 3C  is a cross-sectional view of the base plate mounting into the center swivel. 
       FIG. 4A  is a cross sectional view of the ball lock across line  4 A- 4 A of  FIG. 2A . 
       FIG. 4B  is a cross sectional view of the ball lock across line  4 B- 4 B of  FIG. 2A . 
       FIG. 4C  is a partial cross sectional view of the ball lock across line  4 C- 4 C of  FIG. 4B . 
       FIG. 5A  is an exploded view of the inner and outer legs with the pin exploded out and rotated. 
       FIG. 5B  is a side perspective view of an inner leg. 
       FIG. 5C  is an overhead perspective view of an inner leg. 
       FIG. 5D  is an end perspective view of the inner leg. 
       FIG. 5E  is an overhead perspective view of the side of an outer leg showing holes. 
       FIG. 5F  is a cross sectional view across line  5 F- 5 F of  FIG. 5G . 
       FIG. 5G  is an overhead perspective view of side of an outer leg. 
       FIG. 5H  is an end perspective view of an outer leg. 
       FIG. 5I  is an elevational view in the direction of line  5 I- 5 I of  FIG. 5H . 
       FIG. 5J  is a cross sectional view across line  5 J- 5 J of  FIG. 5I . 
       FIG. 5K  is a cross sectional view of the inner leg button registered in the outer leg hole. 
       FIG. 5L  is a cross sectional view of the inner leg button not registered in the outer leg hole. 
       FIG. 6A  is an exploded view of the bipod rail clamp assembly with the base plate in a cross sectional view for reference. 
       FIG. 6B  is a top perspective view of the base plate. 
       FIG. 6C  is a cross-sectional view of the base plate across lines  6 C- 6 C of  FIG. 6B . 
       FIG. 6D  is a cross-sectional view of the base plate across lines  6 D- 6 D of  FIG. 6B . 
       FIG. 6E  is a cross-sectional view of the base plate across lines  6 E- 6 E of  FIG. 6B . 
       FIG. 6F  is a rear view of the base plate in  FIG. 6B . 
       FIG. 6G  is a rear view of the rail clamp mounted on the base plate. 
       FIG. 6H  is an elevational view of the rail clamp. 
       FIG. 6I  is a cross sectional view of the rail clamp across line  6 I- 6 I of  FIG. 6H . 
       FIG. 7A  is an overhead perspective view showing traversing motion of the firearm mounted on the bipod. 
       FIG. 7B  is a front elevational view showing canting motion of the firearm mounted on the bipod. 
       FIG. 7C  is an overhead and partial cross sectional view of the base plate at a traversing limit. 
       FIG. 7D  is an overhead perspective view of the base plate at a traversing limit. 
   


   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Referring to  FIG. 1A , a bipod  10  according to one embodiment of the invention has two outer legs  12 ,  15 , that are pivotally attached to a center swivel  11 . A cantilevered rail clamp  19  dimensioned for receiving the rail  100  of firearm, is pivotally mounted to a base plate  18 , which is in turn pivotally mounted to the center swivel  11 . The bipod  10  is shown in a deployed condition with inner legs  13 ,  16  in a telescoped condition.  FIG. 1B  shows the bipod  10  in a stored condition with inner legs  13 ,  16  in a fully retracted condition inside of the outer legs  12 ,  15 .  FIG. 1C  shows the bipod  10  in a stored condition while attached to a firearm rail  100 . The bipod  10  in one embodiment is mounted to the firearm  100  such that in the stored position, the distal ends of the legs are oriented toward the muzzle of the firearm in the direction A depicted in  FIG. 1C , or in the stored position such that distal ends the legs are oriented in direction B, away from the muzzle of the firearm. 
   In an embodiment of the present invention as illustrated in  FIGS. 2A-3C , the center swivel  111  comprises several means for mounting the outer legs  112 ,  115  and base plate  118 . As shown in  FIG. 3A , the center swivel contains two swivel leg orifices  136  that accept the ends of the ball retainers  123 . In  FIGS. 2A ,  3 A- 3 B, the center swivel  111  comprises an additional retaining pin orifice  137  in communication with the swivel leg orifices  136 , for holding a retaining pin  138 . In one embodiment, as shown in  FIG. 3B , there are two retaining pin orifices  137  perpendicular to the swivel leg orifices  136  and aligned such that one retaining pin may be inserted through both retaining pin orifices simultaneously. As shown in  FIGS. 2A ,  2 B and  3 B, outer leg limiting pins  127  are inserted into the limit pin orifices  141  which surround the swivel leg orifices  136 . As shown in  FIG. 3A  the center swivel contains o-ring grooves  139  for accepting swivel leg orifice o-rings  126 , which surround the swivel leg orifice  136  and the outer leg limiting pin orifices  141 . 
   In one embodiment, as shown in  FIGS. 3B-3C  and  FIG. 6B , the center swivel  111  has a cavity  140  dimensioned to accept, the end  325  of a base plate  118  and allow traversing motion. The center swivel  111 , comprises, as shown in  FIGS. 3A-3C , a swivel bolt orifice  142  for accepting center swivel shoulder bolt  109 , which is used to attach a base plate  118  while allowing it to traverse. In one embodiment, the shoulder bolt  109  has an Allen head and screws into the bottom of the center swivel, although other securing devises, such as pins may be used. One embodiment as shown in  FIG. 7A  allows a firearm rail  100  and barrel  101  to traverse and is often desired because traversing motion allows a firearm operator to smoothly track a target. One embodiment allows the firearm to traverse up to 40 degrees in each direction, and in another embodiment, up to 45° in either direction. As shown in  FIG. 6A , there is a hole  326  in base plate  118  dimensioned to accept a center swivel shoulder bolt  309 , thereby allowing traversing motion. In one embodiment, as shown in  FIGS. 7C and 7D , the limit of traverse occurs when the base plate  318  hits point  701  or point  702  on the center swivel  111 . 
   In one embodiment, as shown in  FIGS. 2A-4C , the outer legs are secured to the center swivel  111  using a ball lock  125 . Each of the two ball lock leg combinations is a mirror image of the other and only one will be discussed as follows. As shown in  FIG. 2A , the ball lock  125  is a substantially round insert housed in the proximal end of the outer leg  112  securing the leg to the center swivel  111 . In one embodiment as shown in  FIGS. 5E-5J , the outer leg  215  has a cavity with two different diameters  229 , 230  dimensioned to accept the ball lock  125  as shown in an assembled view in  FIG. 2B , which is pressed into a preformed outer leg  112 , although the leg may also be formed around the ball lock  125 . As shown in  FIGS. 4A-4C , the ball lock  125  contains a substantially round orifice  136  and a lip around the circumference closest to the grooves  135  as illustrated in  4 C. In one embodiment, as shown in  FIGS. 4A and 4C , one side of the ball lock  125  contains notches  133  in the orifice  134  for a ball bearing  124  (shown assembled in  FIGS. 2C-2D ).  FIG. 2B  illustrates two ball bearings  124  in each ball lock  125 , although only one ball bearing is necessary, and up to four may be used depending on the tolerances of assembly with four requiring a tighter tolerance. In one embodiment, referring to  FIGS. 4B ,  4 C the other side of the ball lock  125 , which is shown in  FIG. 2B , is in contact with the center swivel  111 , contains limiting grooves  135  as shown in  FIG. 4B  for limit pins  127 . As shown in  FIG. 4C , each notch  133  is deep enough to allow a portion of the ball bearing to rest within it. As shown in  FIG. 2A , and  2 D- 2 F, the ball bearing  124  is held within a ball retainer  123 . In one embodiment, as shown in  FIGS. 2E-2F , the ball retainer comprises a lip  145 , a wide cylindrical portion with one to four orifices  128  for a ball bearing  124 , and a reduced diameter cylindrical portion with one or two orifices  129 . In one embodiment as shown in  FIG. 2F , the wide cylindrical portion includes a bore. As shown in  2 A and  2 B, the ball retainer  123  comprises an orifice  128  that is dimensioned such that only a portion of the of the ball bearing  124  can protrude through the orifice  128 . The ball retainer  123  further comprises a retaining pin hole  129 , which allows it to be pivotally attached to the center swivel  111 . In one embodiment as illustrated in  FIG. 3B , the retaining pin hole  129  goes entirely through the ball retainer  123 . As illustrated in  FIG. 2A , after the ball bearing  124  is inserted into the ball retainer  123 , a plunger return spring  122  is inserted, followed by a plunger  120  with a plunger o-ring  121 . The spring  122  may also be inserted after the ball bearing  124 . As shown in  FIGS. 2G and 2H , the plunger  120  comprises a disk  130  and stem  146  with a reduced diameter section  131  between the bearing end  132  and the disk  130  of the stem  146 . In one embodiment, the stem  146  comprises a beveled edge  143  at the transition between the bearing end  132  and the reduced diameter section  131 . In one embodiment, as shown in  FIG. 2H , the plunger comprises a bore  144 , dimensioned to accept a spring  122  as shown in  FIG. 2D . In one embodiment the relief angle of the bearing surface  132  is less than 90 degrees from horizontal to provide a more gradual release of force on the ball bearing  124  when the plunger is depressed. As shown in  FIG. 2G , the disk  130  comprises a groove  147  for an o-ring  121  as shown in  FIG. 2A . When the outer legs are in a locked position, either deployed or stored, as shown in  FIG. 2C , the plunger  120  is in a non-depressed condition such that ball bearing  124  rests tightly on the bearing end  132  while in a notch  133 . One end of spring  122  rests in the bore  144  the plunger stem  146  and the other end rests on the base of the bore  148  of the ball retainer  123 . In one embodiment, the spring  122  is designed and dimensioned such that when the plunger  120  is in a non-depressed condition as illustrated in  FIG. 2C , the spring  122  applies enough force to keep the ball bearing  124  in contact with the bearing end  132 . Additionally, the spring  122  supplies resistance when force is applied, typically by an operator, to the plunger  120 , by trying to return the plunger  120  to the non-depressed position. In one embodiment, as shown in  FIG. 2D , when the plunger  120  is depressed such that the reduced diameter section  131  aligns with the ball bearing  124 , the ball bearing  124  no longer rests tightly against the bearing end  132  and thus may leave the notch  133  in the ball lock  125 , allowing the outer leg to be rotated. At this time, to lock the outer leg, the plunger  120  is released so that it returns to a non-depressed condition as shown in  FIG. 2C . This allows plunger  120  to establish contact with the ball bearing  124  by transitioning from the reduced diameter section  131 , to the beveled edge  143 , and onto the bearing end  132 . In one embodiment, as shown in  FIGS. 2A and 2B , limiting pins  127  are attached to the center swivel  111 , and lie within the limiting grooves  135  of the ball lock  125 , and serve to limit the range of motion of the outer legs. 
   As shown in  FIG. 5A , the outer leg  215  is hollow and allows inner leg  216  to axially slide within it. In one embodiment of the invention the outer leg  215  is oval in shape and each inner leg  216  also has a foot  217  at its distal end with a gripping surface to prevent lateral movement on various surfaces such as solid ground or sand. Each outer leg/inner leg combination is a mirror image of the other and only one will be discussed below. 
   In one embodiment of the invention, as show in  FIG. 5C , inner leg  216  comprises a backbone, rails  222 ,  223 , a tab  225 , button  219 , and a foot  217 . The backbone of the inner leg  216  is solid and substantially circular in shape with two rails  222 ,  223  that run parallel to the backbone of the inner leg  216 . The first rail  222  runs continuously from the tab  225  to the foot  217  of the inner leg  216 . The second rail  223  is located 180 degrees from the first rail  222  and has a gap  224  along its length closest to the distal end of the inner leg  216 . These rails  222 ,  223 , among other things, prevent the inner leg  216  from twisting within the outer leg  215 . As show in  FIGS. 5A ,  5 F, and  5 H, the outer leg  215  contains two slots  218  which are dimensioned to accept the rails  222 ,  223  of the inner leg  216 , and to allow the inner leg  216  to slide axially with respect to the outer leg  215 . In one embodiment, the outer leg  215  also contains a hole  221  near its distal end and near a groove  218 , which accepts a stop pin  228 . This stop pin  228  slides along the gap  224  as the inner leg  216  is telescoped in or out of the outer leg  215  and serves as a limit stop. When the stop pin  228  reaches the ends of gap  224 , the inner leg  216  is either fully telescoped or fully retracted. In one embodiment, the outer leg may include additional clearing holes  21  as show in  FIG. 1A . When pushing the inner leg  16  within the outer leg  15 , these holes  21  aid in clearing any debris, such as sand, that is lodged in the outer leg. In one embodiment as shown in  FIGS. 1A and 1B , the outer legs also comprise raised ridges  20  and  22  with holes  220  as shown in  FIG. 5A . As shown in  FIGS. 1B and 1C , the outer and inner legs are dimensioned such that when the inner legs are in the fully retracted position, and the outer legs are fully stowed against the firearm, no vital parts of the firearm, such as an ejection port, are obstructed. In one embodiment the bipod does not interfere with the vertical fore grips, rail panels, tactical lights, or lasers (not shown) on a firearm. In one embodiment, as shown in  FIG. 5D , portions of the feet  217  may be designed to accommodate any protruding features on the firearm rail, or the firearm itself. In one embodiment, the feet  217  are dimensioned with a large amount of surface area and an effective non-skid mechanism, such as teeth, for maximum floatation and traction on sand, mud, earth, ice, and concrete. 
   In one embodiment, as shown in  FIGS. 5A-5D , to secure the inner leg  216  with respect to the outer leg  215  at various relative positions, the inner leg  216  has a button  219  on a flexible tab  225  molded into the proximal end of the leg  216 . In one embodiment, as illustrated in  FIGS. 1A and 1B , the outer leg  215  has raised ridges  21  on the outer surface. In one embodiment, as shown in  FIG. 5A , the outer leg has a series of holes  220  dimensioned to receive a button  219  and the raised ridges  231  are approximately the same width as the button  219  and are slightly taller than the button  219  when said button is in registration with the holes  220  as illustrated in  FIG. 5K . In one embodiment, the raised ridges  231  serve to keep the button  219  from being accidentally depressed, allow easy access to the button  219  with gloved hands, and also serve as an insulating surface when the outer legs  215  are in a stowed position near a hot firearm as in  FIG. 1C . In one embodiment of the invention, as shown in  FIG. 5A , the holes  220  and the button  219  are oval in shape and are oriented with the major axis parallel to the long axis of the outer leg  215 . In one embodiment, as shown in  FIG. 5K , the button  219  extends through the holes  220  when the inner leg  216  brings the button  219  in registration with the holes  220 , and by doing so prevents the inner leg  216  from sliding with respect to the outer leg  215 . In one embodiment, as shown in  FIGS. 5B and 5K , the top of the button  219  is curved and has a sloping end  226  that allows the edge of the holes  220  to flex the tab  225  inward, while an operator pulls on the foot  217  of the inner leg  216 . This allows the inner leg  216  to slide out of the outer leg  215  without having to depress the button  219 . In one embodiment, the button  219  also has a non-sloping, essentially vertical end  227  which will catch on the holes  220  when the inner leg  216  is pushed into the outer leg  215 . In order to push the inner leg  216  further, the button  219  needs to be depressed and held such that the button  219  goes out of registration of the holes  220 , while the inner leg  216  is pushed into the outer leg  215 . In one embodiment, the tab  225  is molded such that there is a resisting force that discourages flexing and or bending. The tab  225  in  FIGS. 5A and 5K  is shown in a resting mode. When the inner leg  216  is inserted into the outer leg  215  and the tab  225  registers through a hole  220 , there is substantially no resisting force in the tab  225 . As shown in  5 L, as the button  219  is depressed, the resisting force opposes the depression force and acts to return the button  219  to the resting position. In one embodiment of the invention, the tab may be replaced with a button and spring combination mounted on the backbone of the inner leg, where the spring would provide the resisting force. 
   One embodiment of the invention allows a firearm rail  100  and barrel  101  to cant, as shown in  FIG. 7B , without having to laterally adjust the position of the legs. One embodiment allows the firearm to cant up to 15 degrees in either direction, and in another embodiment, up to about 22.5° in either direction. Canting motion allows simple vertical sight correction of the firearm over slightly irregular ground. In one embodiment, as shown in  FIG. 2B , a firearm rail  100  is attached to a rail clamp  319 , which is in turn attached to a base plate  318 . In one embodiment, as shown in  FIG. 6A , the rail clamp  319  comprises a rail clamp bar  320  and bores  321  for rail clamp bar fasteners  334  in which the fasteners  334  are captured threaded screws that can be turned with a flat bladed screwdriver or hex head wrench. In one embodiment, the rail clamp  319  and rail clamp bar  320 , as shown in  FIGS. 6H and 6I , are dimensioned to accept M4 carbines and M16 rifles, where the rail clamp  319  attaches to a Picatinny designed Mil-Std-1913 rail. In one embodiment, the rail clamp  319  comprises two rounded journals  331 ,  332  on the bottom with holes  333  for accepting a rail clamp pivot pin  322 . The ability to pivot around pin  322 , as shown in  FIG. 6G , allows the firearm to cant without laterally moving the legs of the bipod. In one embodiment, as shown in  FIGS. 6A and 6B , the base plate  318  has one end  325  that as been rounded and dimensioned to fit into a slot  140  on the center swivel as shown in  FIGS. 3B and 3C . In one embodiment, referring to  FIGS. 6A and 6B , the base plate  318  also has a circular groove  329  which allows a retainer  323  to be put on the end of a rail claim pivot pin  322 . In one embodiment a split ring type of retainer  323  is used, but any retaining means such as a nut may be used. In one embodiment, the base plate  318  also has two rounded grooves  327  and  328  sized to accept the rounded lobes  331  and  332  on the rail claim  319  and rounded grooves  327  and  328  contain holes at the bottom, as shown in  FIG. 6 , dimensioned such that the lobes  331 ,  332  do not touch the base plate  118 . The pivot pin  322  carries the load from the rail clamp  319  to the base plate  318 . In one embodiment, there are two holes  330  on the base plate  318  that accept buffers  324  in the shape of solid cylinders, which limit and resist cant of the rail clamp  319 . In one embodiment, silent buffers such as neoprene solid cylinders are used, but any solid material may be used, including plastics, polymers, metals, rubber, and the like. In one embodiment as shown in  FIGS. 6C-6F , there is also a hole  333  running length wise through the base plate  318  dimensioned to accept the rail clamp pivot pin  322 . In one embodiment as shown in  FIG. 6G , as the rail clamp  319  is pivoted around  322  to one side, the rail clamp  319  will contact a buffer  324  which will resist and/or limit further canting. If the rail clamp is pivoted in the opposite direction, the rail clamp bar  320  will contact a buffer  324 , thus resisting and/or limiting further canting in the opposite direction. 
   In an embodiment the major components of the bipod may be constructed of metal, including aluminum, stainless steel, etc. and although this construction produces a strong bipod, it may be too heavy for certain operations. In one embodiment, certain components may be constructed of plastics, carbon fiber, resins, rubber and other solid materials. In one embodiment, the outer legs and base plate are injection molded with CELSTRAN™ available from Entec Polymers, Inc. The molded parts from this resin may withstand temperatures up to approximately 700° F. In one embodiment, the inner legs are injected carbon fiber and the center swivel and rail clamp assembly are 7071 T6 aluminum with a type III hard anodized coat, and the remainder of the assembly is heat treated stainless steel that is sealed with o-rings. In one embodiment, the leg joints at the center swivel are pre-lubricated and sealed, and thus minimal maintenance is required to keep them functioning properly because environmental elements, such as sand, can be merely brushed off or rinsed with water. Additionally, because the bipod is modular in construction, should any portion suffer damage, it can be replaced with common tools in the field. One embodiment of the invention is essentially silent in operation, with no external springs to resonate with sound when accidentally struck. 
   While the invention has been described in connection with what are considered to be exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
A bipod for a firearm is provided, including a body with cutouts to receive a bipod base, and a pair of legs. The bipod base is pivotally mounted to the body, and a firearm mounting bracket is pivotally mounted to the bipod base, allowing for a traversing and/or canting motion. A ball lock mounts each leg to the body, allowing the legs to be independently deployed or stored with the push of a plunger. The legs also telescope to allow adjustment of the bipod height.