Patent Document

CROSS REFERENCES TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application No. 60/573,978 filed May 24, 2004. 

   FIELD OF THE INVENTION 
   This invention relates to adjustable firearm support for adjustably supporting the stock of a rifle. 
   BACKGROUND OF THE INVENTION 
   Some rifles include stocks which have a generally upright interior surface which forward of the butt surface. Such rifles also have a longitudinal countersunk bore communicating between the upright interior surface and the butt surface for carrying a bolt for attaching accessories which are often mounted to the interior surface. Marksmen using rifles either as military snipers or as target shooters will often support the forward end of a rifle with a stationary bi-pod support and simultaneously support the butt end of the rifle in a way that provides fine adjustment of the elevation of the rifle. Accordingly, it is advantageous if an adjustable support is provided for rifles having an interior mounting surface as described above. Applicant&#39;s U.S. Pat. No. 5,248,868, which is incorporated here as if repeated verbatim hereafter, teaches an adjustable support for supporting the stock end of a rifle. The adjustable support taught in U.S. Pat. No. 5,248,868 is generally adapted for clamping to the type of firearm stock having sling stud imbedded in the lower surface of the firearm stock toward the butt end of the stock. It is also advantageous if an adjustable support can be rotated into a retracted position with a minimum of effort and conversely rotated into an extended position for use with a minimum of effort. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In an embodiment of the present invention the aforementioned needs are addressed by an adjustable firearm support including a base member and an adjustable support leg. The base member is adapted for mounting to the upright inside surface of a firearm stock. More particularly, the base member includes a generally horizontal counter sunk bore for retaining a fastener for fastening to the inside surface of the firearm stock. Preferably, the firearm stock also includes a countersunk bore for retaining a bolt and the base member retains a unique internally treaded socket head fastener which engages the bolt retained by the firearm stock and thus fixes the base member against the inside upright surface of the stock. The support leg of the adjustable firearm support is connected to the base member portion by a positioning block. The positioning block is pivotably mounted within the base member for rotation between a first position and a second position. When the positioning block is in the first position, the attached adjustable support leg is in a first retracted position. When the positioning block is in the second position, the adjustable support leg is in a second, extended position for use. A spring biased positioning pin is also mounted within the base member. The spring biased positioning pin includes a relatively wide portion and a relatively narrow portion. The positioning block is located within the base member and shaped such that it can rotate without interfering with the narrow portion of the positioning pin when the positioning pin is urged sufficiently against its spring bias. The positioning block also has two recesses which are shaped and located to capture the wider portion of the positioning pin and thus lock the positioning block in either one of two desired positions preferably corresponding to either the first retracted position or the second extended position. When the wide portion of the positioning pin is captured by one of the spaced recess of the positioning block, a portion of the positioning pin protrudes from the base member so that the positioning pin can be manually urged against its bias and out of engagement by an operator. Thus, an operator, by pressing the protruding portion of the positioning pin, may selectively unlock the positioning block so that the positioning block may be quickly rotated to one of either the first retracted or second extended positions. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of the adjustable firearm support of the present invention mounted to a firearm stock shown in reference 
       FIG. 2  is an exploded front view of the adjustable firearm support of the present invention. 
       FIG. 2A  is an enlarged side view of positioning block  50  taken from plane A—A indicated in  FIG. 2 . 
       FIG. 3  is a top view of the base member  20 . 
       FIG. 4  is a section view taken from plane  4 — 4  indicated in  FIG. 2   
   

   DETAILED DESCRIPTION 
   Referring to the drawings,  FIG. 1  an adjustable firearm support  10  is mounted to a firearm stock  5  of a firearm  4 .  FIG. 1  is a side view of adjustable firearm support  10 . As can be seen in  FIG. 1 , firearm stock  5  is of the type which includes a butt portion  5 A and an interior, generally upright surface  5 C. Adjustable firearm support  10  includes a base member  20 , a positioning block  50 , a support rod  60 , a binding sleeve  70  and a support leg  80 . Base member  20  is secured to upright surface  5 C of firearm stock  5  using a fastener arrangement which will be described in detail below. As will also be described in greater detail below, support leg  80  is threadably mounted to support rod  60  so that it may be rotated to raise and lower firearm stock  5  in a finely adjustable manner for finely adjusting the elevation angle of firearm  4 . As will be readily understood by the skilled reader, firearm stock  5  is preferably supported at its front end by a bi-pod or similar device.  FIG. 1  shows support leg  80  and other elements in an extended position for use. Support leg  80  and other elements are also shown in phantom to illustrate a retracted position in  FIG. 1 . 
     FIG. 2  is an exploded view of the adjustable support  10  of the present invention. Adjustable support  10  is mounted to firearm  4  by base member  20 . Support rod  60  is a threaded element which carries a binding sleeve  70  and support leg  80 . Both binding sleeve  70  and support leg  80  have threaded bores for engaging the external threads of support rod  60 . Positioning block  50  is for pivotably mounting support rod  60  and the elements carried by support rod  60  to base member  20 . 
   Base member  20  is shown in  FIG. 2  and is shown in more detail in  FIGS. 3 and 4 .  FIG. 2  shows a front view of base member  20 . As can be seen in  FIG. 2 , base member  20  is rectangular in shape and is oriented such that its longest sides are generally upright. A generally horizontal counter bored hole  24  extends between opposite front and back surfaces of base member  20 . A blind bored hole  32 , is positioned under counter bored hole  24  and oriented generally perpendicularly with respect to counter bored hole  24 . An axially aligned pair of holes  26 A and  26 B is generally parallel to and positioned under blind bored hole  32 . A positioning block slot  22  extends from the back and bottom surfaces of base member  20  in a normal and intersecting relationship with both blind bored hole  32  and holes  26 A and  26 B.  FIG. 3  is a top view of the base member  20  showing the cradle  27  which is shaped for fitting up against inside surface  5 C of firearm stock  5  shown in  FIG. 4 . Positioning block slot  22  is shaped and sized for receiving positioning block  50 . Positioning block  50  is pivotably mounted within within positioning block slot  22  by a positioning block pin  54 . Bores  26 A and  26 B on opposite sides of positioning block slot  22  and a corresponding bore  52  in positioning block  50  are all axially aligned for receiving positioning block pin  54 . Positioning block  50  has a threaded hole  56  in its lower surface for the fixed attachment of the upper threaded end of support rod  60 . 
   As described above, positioning block  50  carries the pivoting portions of adjustable support  10 , namely threaded support rod  60 , binding sleeve  60  and support leg  80  which may be considered as an assembly indicated by reference character A in  FIG. 2 . Base member  20  and assembly A indicated in  FIG. 2  are arranged such that assembly A may be selectively locked in either the retracted or extended positions shown in  FIG. 1  or unlocked and rotated between those two positions. As described above, positioning block  50  is pivotably mounted within base member  20 . Positioning block  50  and base member  20  cooperate within a releasable locking mechanism for selectively locking the pivoting portions of adjustable support  10  either in the first, raised position as shown in phantom in  FIG. 1  or in the second extended or lowered position as shown with solid lines in  FIG. 1 . The releasable locking mechanism includes a positioning pin  30  which is received by a blind hole  32  in base member  20 . Positioning pin  30  is biased to protrude from base member  20  by a spring  33  allow manual access by an operator. Positioning pin  30  includes a wide portion  30 A toward its inserted end and a narrow portion  30 B adjacent to wide portion  30 A. As can be best seen in  FIG. 2A , positioning block  50  includes a curved upper surface  52 A which preferably describes a circular arc centered around the center of rotation of positioning block  50 . Positioning pin  30  and positioning block  50  are arranged within base member  20  so that upper surface  52 A of positioning block  50  clears narrow portion  30 B of positioning pin  30  as positioning block  50  rotates. These elements are also arranged such that wide portion  30 A of positioning pin  30  does not clear upper surface  52 A of positioning block  50 . Thus, when positioning pin  30  and positioning block  50  are installed in base member  20 , positioning block  50  retains spring biased positioning pin  30 .  FIG. 2A  is a side view of positioning block  50  taken from plane A—A indicated in  FIG. 2 . As can be seen in  FIG. 2A , positioning block  50  includes two recesses, a first recess  53 A and a second recess  53 B. First and second recesses  53 A and  53 B are similarly shaped to receive a portion of wide portion  30 A of positioning pin  30 . Thus, when either first or second recess  53 A or  53 B captures part of the end of wide portion  30 A, positioning block  50  is locked and can not rotate within base member  20 . More particularly, when first recess  53 A captures wide portion  30 A, adjustable support  10  is locked in the first retracted position shown in phantom in  FIG. 1 . When second recess  53 B captures wide portion  30 A, adjustable support  10  is locked in the second extended position shown in solid lines in  FIG. 1 . Positioning pin  30  is arranged so that a portion of positioning pin  30  protrudes from base member  20  by a sufficient amount to allow an operator to depress the protruding end of positioning pin  30  against its spring bias and cause wide portion  30 A to completely escape from either one of first or second recess  53 A or  53 B. Thus an operator, by depressing positioning pin  30  may unlock positioning block  50  so that adjustable support  10  may be rotated between the first retracted position and the second extended position described above. It is preferable that positioning pin  30  and positioning block  50  or at least their corresponding engaging surfaces in the above described locking arrangement be fashioned from a hard tough material such as hardened steel. 
   As can be seen in  FIG. 2 , support rod  60  includes a threaded shaft  62  and a bolt head  64 . Support rod  60  can be fabricated from steel or brass or any material suitable for holding threaded surfaces. Support rod  60  could be easily fabricated from a socket head cap screw. 
   As can also be seen in  FIG. 2 , binding sleeve  70  includes a knurled portion  72  with an axial bore (not shown) which is threaded to receive the threaded shaft  62  of support rod  60 . Binding sleeve  70  can be fabricated from steel or brass or any material suitable for holding knurled and threaded surfaces. 
   Support leg  80  is also shown in  FIG. 2 . It includes a top surface  82 , a threaded axial bore  84 , a counter bore  84 A, a large handle body  86 , and a rotation member  88 . Large handle body  86  is designed to be easily manipulated by an operator. Threaded axial bore  84  is in a normal relationship to top surface  82  and is adapted to receive threaded portion  62  of support rod  60 . Counter bore  84 A extends from the bottom end of handle body  86  and meets threaded axial bore  84  near the center of handle body  86 . Rotation member  88  closes off counter bore  84 A and is adapted to turn on a stable surface. Support leg  80  can be made from a hard plastic capable of accepting internal threads or may have a metal insert for providing threaded axial bore  84 . 
     FIG. 4  is a section view of the adjustable firearm support  10  taken from plane  4 — 4  of  FIG. 2  with a firearm stock in relief.  FIG. 4  shows the assembled adjustable firearm support  10  in relationship to a firearm stock  5  and a means for attaching adjustable firearm support  10  by utilizing a butt pad bolt  5 E provided with firearm  4 . An internally threaded socket head fastener  90  is used to engage butt pad bolt  5 E and pull base member  20  tightly against inside surface  5 C of firearm stock  5 . Preferably, socket head fastener  90  should be of high strength steel capable of withstanding significant stress. Retaining clip  93  may be of common manufacture and configured to provide enough tension on internally threaded socket head fastener  90  to retain socket head fastener  90  within base member  20 . In the absence of a butt pad bolt  5 E, internally threaded socket head fastener  90  and retaining clip  93  are not required and adjustable firearm support  10  may be attached to firearm stock  5  by means of a common threaded fastener such as a socket head cap screw. 
   Adjustable firearm support  10  can be assembled as follows: First, support rod  60  is threaded into support leg  80  so that the bolt head  64  of support rod  60  is closely adjacent to top end of counter bore  84 A of support leg  80 . Second, rotation member  88  is pressed into the bottom of support leg  80 . Third, binding sleeve  72  is threaded down onto support rod  60  until it is closely adjacent to top surface  82  of support leg  80 . Forth, positioning block  50  is permanently threaded onto support rod  60  by use of thread locking compound thereby creating a permanent assembly indicated by A in  FIG. 2 . Fifth, spring  33  is placed into the bored blind hole  32  of the base member  20 . Sixth, positioning pin  30  is pressed against poisoning spring  33  within blind bored hole  32 . Seventh, and finally, the positioning pin  30  is depressed and positioning block  50  is inserted into positioning block slot  22  and is pivotably mounted to the base member  20  by pressing positioning block pivot pin  54  through the aligned holes  26 A and  26 B in base member  20  and hole  52  in positioning block  50 . 
   Assembled adjustable firearm support  10  may be mounted to firearm stock  5  by means of socket head fastener  90  and butt pad bolt  5 E as described above. As internally threaded socket head fastener  90  is threaded onto the butt pad bolt  5 E, cradle  27  of base member  20  will firmly engage internal surface  5 C of firearm stock  5 . By depressing the positioning pin  30  against the bias of spring  33 , an operator may disengage the wide portion  30 A of positioning pin  30  from either recess  53 A or  53 B for movement between the first retracted position and the second extended position. Once adjustable firearm support  10  is locked in the second extended position as shown in  FIG. 1  with solid lines, rotation member  88  of support leg  80  may be placed on a stable surface and support leg  80  may be rotated about support rod  60  to finely adjust the elevation of firearm stock  5 . 
   It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof. equivalents thereof.

Technology Category: f