Abstract:
An improved gun stock construction that substantially reduces both the recoil and the tendency of the gun to move upward or jerk when it is fired. The stock is formed with two sections having a flexible hinge mechanism. This structure creates a moment arm or couple which opposes the tendency of the gun to move upward when it is fired. This invention relates to improvements in a gun construction and more particularly to the improvement in gunstock that permits better control of the gun by the operator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     This invention relates to gunstocks and particularly to gunstocks having two sections in pivotal relation to each other. 
     2. Description of the Prior Art 
     The prior art teaches that it is commonly known that the recoil of a gun causes the barrel to shift in a generally upward direction and to the left. In an automatic gun which is firing rapidly, this becomes a force which is practically uncontrollable so that effective use of the weapon is not always possible after the first few shots when rapid firing is being used. 
     Attempts have been made to reduce this effect. One example is found in U.S. Pat. No. 3,388,494 to John Kimball, a coninventor of the instant invention. That patent disclosed a gun stock that has a stock formed from two sections having a flexible strap interposed between the sections adjacent to the top of the stock and a spring between the sections below the strap so that the two sections can rotate in a segment of an arc relative to each other and to -the top of the stock. This structure creates a moment arm or couple, which opposes the tendency of the gun to move upward when it is fired. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Despite the improvements in this design, there are still problems with it. The instant invention is an improvement over this design. It replaces the flexible strap at the top, which tends to bend in a random pattern with a pin hinge that precisely controls the arc of travel, which produces a precise placement in relation to the barrel centerline. 
     The new device is self-adjusting and does not have to be adjusted for different ranges. This is done through the manipulation of a set constant applied force. 
     The system uses an interlocking mechanism that adds rigidity to the stock. 
     Finally, it uses the combination of springs and rubber membranes as a two-step mechanism, which produces a smoother operation. 
     In its basic form, the gunstock has a front piece that attaches to the front part of the weapon and a rear piece that forms the butt of the stock. These two pieces are attached at the top at a pivot point that allows the two pieces to swing in an arc. A pin is placed in a track in the rear piece and is fitted with a spring. The distal end of the pin has a flat head that fits into the bottom of the front piece. Here, the head of the pin is held securely. This pin and spring are designed to allow restricted movement of the rear portion with respect to the front portion as the weapon is fired. This produces an oscillation that absorbs the moment forces that would normally pitch the gun upwards. 
     It is an object of the present invention to provide an improved gun stock which not only reduces to a very minimum the change of position of the muzzle of the gun in continued firing but also relieves the shock against the shoulder of the gunner making it possible for the operator to maintain a stable position with a well-aimed firearm under rapid firing conditions. 
     Another object of the invention is a control device for a gunstock that is readily-adjustable depending on the ammunition used and the needs of a particular operator. 
     It is a further object of the invention to provide a fully-automatic, shoulder-fired weapon which converts recoil energy into a beneficial effect which results in dropping the barrel and bringing it back into the previously mounted position. Thus, the general tendency of the barrel to rise after each shot is eliminated; and, as a secondary advantage, there is dampening of the recoil in the absorption of the energy to accomplish the beneficial result causing less disturbance of the gunner and the gun attitude. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the assembled gunstock. 
     FIG. 2 is a perspective view of the internal structure of the right side of the gunstock. 
     FIG. 3 is a perspective view of the inside of the left side of the stationary section. 
     FIG. 4 is a perspective view of the outside of the left side of the stationary section. 
     FIG. 5 is a second perspective view of the inside of the left side of the stationary section. 
     FIG. 6 is an end view of the left side of the stationary section. 
     FIG. 7 is a side view of the outside of the right side of the stationary section. 
     FIG. 8 is a perspective view of the inside of the right side of the rotating section. 
     FIG. 9 is a perspective view of the outside of the right side of the rotating section. 
     FIG. 10 is a side view of the outside of the right side of the rotating section. 
     FIG. 11 is an end view of the right side of the rotating section. 
     FIG. 12 is a side view of the inside of the right side of the rotating section. 
     FIG. 13 is a perspective view of the right side of the sleeve section. 
     FIG. 14 is a perspective view of the left side of the sleeve section. 
     FIG. 15 is a right end view of the sleeve section. 
     FIG. 16 is a side view of the sleeve section. 
     FIG. 17 is a left end view of the sleeve section. 
     FIG. 18 is a perspective view of the spring pin. 
     FIG. 19 is a side view of the spring pin. 
     FIG. 20 is a side view of the spring pin rotated 90 degrees from FIG.  19 . 
     FIG. 21 is a top view of the spring pin. 
     FIG. 22 is a perspective view of the pivot pin. 
     FIG. 23 is a side view of the pivot pin. 
     FIG. 24 is a top view of the spring pin lever. 
     FIG. 25 is a front view of the spring pin lever. 
     FIG. 26 is a side view of the spring pin lever. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, the new gunstock  1  is shown fully assembled. The gunstock has four main parts. First this receiver extension  2  that secures the stock to the main part of the weapon. Second is the stationary portion  3 . Third is the rotating portion  4 . And the last element is a sleeve  6 . A slot  12  is used for a gun sling. 
     FIG. 2 shows the interior of the right side of the assembly. The receiver extension  2  fits into a recess in both the stationary and rotating portions. The stationary portion  3  is attached to the rotating portion  4  at two places. First, a pivot pin  6  (see FIG. 22) that passes through holes in both the stationary portions  3  and the rotating portion  4  forms a pivot point  5 . If the receiver extension were not in place, this pivot would allow the stationary portion  3  and the rotating portion  4  to pivot freely about the pin. The second point of attachment is at the sliding spring pin  7 . The head of the sliding spring pin  7  is held in a slot  8  formed in the stationary portion  3  as shown. The end of the spring pin  7  extends back to meet a channel  8  in the rotating portion  4 . Note that the channel  8  is curved. This allows the rotating portion  4  to rotate instead of sliding in a flat plane. A spring  10  is used to return the rotating portion to its starting position for the next recoil. FIG. 2 also shows a second spring pin  20  that is an adjustment pin. An adjustment pin lever  22  is also shown. Note that the function of these two components is discussed below. 
     In the preferred embodiment, the device is made from cast parts. Thus, the figures show typical structures found in casting. 
     FIG. 3 shows the left side of the stationary portion  3   a . FIG. 4 shows the right side  3   b . In this figure, the slot  11  for the receiver extension and the slot  12  for the sling are shown. The slot  8  for the head of the spring pin  7  is shown. Behind that slot is a vertical channel  25  that holds the adjustment pin  20  as discussed below. Under that channel is a small recess  23  in which the adjustment lever  22  is placed. Note also that the piece has a number of openings  30  for fasteners  50 . These fasteners are shown in other figures (e.g., FIG.  2 ). Note that the stationary portion  3  has an engagement arm  26  that aligns with the rotating portion  4 . The hole  5   a  is the pivot point in the stationary portion  3 . Through here, the pivot pin  6  is placed. 
     FIGS. 4-7 show additional views of the stationary portion. FIG. 4 shows the right side pivot hole  5   b  that aligns with pivot  5   a . Figures and  6  show views of the left side  3   a . FIG. 7 is a side view of the right side  3   b.    
     FIGS. 8-12 show details of the rotating portion. Note that these views show only one side. The other side is a mirror image. FIG. 11 shows a front view of the side. 
     As shown in FIG. 12, the curved slot  9  for the spring pin is shown. This slot works to cause the rotating part of the stock to rotate on recoil. As the rifle recoils, it pushes backward. Because the rotating portion is not fixed, the movement causes the spring pin  7  to slide along the channel  9 . As it does so, the rotating portion pivots about the pivot pin. This causes the muzzle of the rifle to drop, which counters the natural tendency for the muzzle to rise. The spring  10  forces the forward part of the gun forward so that the stock is ready to receive the next recoil. 
     Note that the channel  11   a  for the receiver extension has a triangular gap  30  formed at the back. As shown in FIG. 2, the gap is above the receiver extension when it is in place. This gap is necessary to provide space for the rotating portion to rotate without being impeded by the receiver extension. Otherwise, the rotating portion would be held rigidly by the receiver extension and the offsetting rotation to counter the lifting moment of the muzzle could not be developed. 
     Note also that the rotating portion  4  also has a recessed portion  35  that accepts the engagement arm  26  of the stationary portion  3 . A hole  4   a  is used to hold the pivot pin  6 , as discussed above. This forms the pivot point for the entire assembly. 
     FIGS. 13-17 show details for the sleeve  5 . Due to the structure of the parts, the front half of the sleeve is designed to conform to the shape of the stationary portion and the back half of the sleeve is designed to conform to the rotating portion. The purpose of the sleeve is to fit over the joined parts to present a finished appearance and to protect the user from the moving elements when in use. The sleeve can be molded in two pieces and joined at the center as shown. Of course, the interior shape of the sleeve can be made to conform to whatever shape the other components may take, or as needed to fit different weapon configurations. 
     FIGS. 18-21 show details of the spring pin and the adjustment pin  20 . These pins  7  and  20  have a flat head  40  and a vertical shaft  41  as shown. A hole  42  is placed through the distal end of the vertical shaft  41 . The hole  42  is used to secure a spring  10  when it is installed. 
     FIGS. 22 and 23 show the pivot pin  6 . This pin is a simple cylindrical pin that has beveled edges on the top and bottom. It has a length sufficient to fit between the joined stationary and rotating parts. 
     FIGS. 25-27 show details of the adjusting lever  22 . This lever is a flat bar that has a keyhole  60  formed in it. The adjustment lever is used in concert with the adjustment pin  20 . This pin  20  and lever  22  are used to position the gunstock on the receiver extension. As shown on FIG. 2, the lower part of the receiver extension  2  is fitted with a number of detents  17 . In FIG. 2, the pin  20  is sitting in the first detents. Receiver extensions have varying numbers of detents. Typically ranging from 4 to 7. The detents  17  allow the stock to be place along the receiver extension in a number of positions by simply moving the adjustment pin  20  from one detent  17  to another. The adjustment lever  22  is designed to do this when the stock is fully assembled (as in FIG.  1 ). The lever disengages the pin  20  from a detent, which allows the free travel of the stock to the next detent, or to any one of the detents desired. The adjustment pin and lever are the only means for positioning and holding the gunstock in any given position along the length of the receiver extension. 
     The present disclosure should not be construed in any limited sense other than that limited by the scope of the claims having regard to the teachings herein and the prior art being apparent with the preferred form of the invention disclosed herein and which reveals details of structure of a preferred form necessary for a better understanding of the invention and may be subject to change by skilled persons within the scope of the invention without departing from the concept thereof.