Abstract:
A system and method for manufacturing a mid-grip high-powered pistol by modifying an existing rifle receiver, wherein a portion of the original trigger is removed, a new trigger is added in a position forward of the partially removed original trigger, and the new trigger is coupled to the remaining portion of the original trigger via an extension, wherein a recoil lug is added to the rifle receiver to handle the recoil, a plurality of different length barrels can be coupled to the new pistol, and a pivot pin diameter and location of a forearm lug prevent creation of an illegal rifle.

Description:
BACKGROUND 
     1. The Field of the Invention 
     This invention relates generally to firearms that are converted from an original form to provide a new function as a different type of firearm. Specifically, the invention is a rifle receiver that is modified to be a high quality mid-grip high-powered pistol, capable of accepting barrels of various calibers, incorporating a recoil plug as part of the design to thereby handle the greater action of the pistol, and creation of a pistol stock and forearm stock that enables the pistol to function properly. 
     2. The State of the Art 
     A new group of handguns has been created for use in hunting big game and for long range target competition. These handguns or high-powered pistols are essentially single-shot or repeating rifles with shortened barrels and buttstock, and are capable of delivering rifle energies. 
     The state of the prior art of high-powered pistols is divided into two groups. The first group consists of pistols that are directly manufactured as such. The second groups consists of pistols that are created as a result of a retro-fit or modification of other firearms which results in the creation of the pistol. It is noted that regardless of which group a high-powered pistol comes from, the performance or attributes can vary greatly depending upon the specific features that are incorporated into the design. 
     Whether a user is going to use a high-powered pistol for game hunting or target competition, there are certain desirable attributes that are common to each purpose. Obviously, accuracy is of paramount concern. Beyond this particular attribute, however, there can be significant differences in functionality. For example, the user may desire a particular type of action. The possible types of action of high-powered pistols include lever action, break action, bolt action, and falling block. 
     Creating a retrofit high-powered pistol is typically done to bring some characteristics of the original firearm to the design, provide a particular action, or to create a unique firearm. Regardless of the purpose, the retrofit is generally done to bring some advantageous or desirable feature to a firearm. 
     Accordingly, it would be an advantage over the prior art to provide a low cost pistol having a mid-grip design, a single action, and the ability to exchange barrels of various lengths and calibers as desired. It would be another advantage over the prior art to provide these features in a high-powered pistol that utilizes a reliable rifle receiver that is well-known and proven design in the industry. Furthermore, these advantageous features can be provided on many popular rifle receiver designs. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a system and method for manufacturing a mid-grip high-powered pistol. 
     It is another object to modify a rifle receiver to function as the mid-grip high-powered pistol. 
     It is another object to modify the rifle receiver so as to include a recoil lug. 
     It is another object to modify the rifle receiver by removing the rifle stock and to add a new pistol stock behind the rifle action. 
     It is another object to modify the rifle receiver so as to remove a portion of the existing rifle trigger, and then dispose a new trigger in a position that is forward of the removed portion of the old rifle trigger. 
     It is another object to modify the rifle receiver so as to be capable of receiving a plurality of different length pistol barrels. 
     It is another object to modify the rifle receiver so as to be capable of receiving a plurality of different pistol barrels of various calibers. 
     It is another object to modify the rifle receiver so that it cannot use pistol barrels that would result in the creation of an illegal short-barreled rifle. 
     The above objects are realized in a specific illustrative embodiment of a system and method for manufacturing a mid-grip high-powered pistol by modifying an existing rifle receiver, wherein a portion of the original trigger is removed, a new trigger is added in a position forward of the partially removed original trigger, and the new trigger is coupled to the remaining portion of the original trigger via an extension, wherein a recoil lug is added to the rifle receiver to handle the recoil, a plurality of different length barrels can be coupled to the new pistol, and a pivot pin diameter and location of a forearm lug prevent creation of an illegal rifle. 
     In accordance with a first aspect of the invention, the rifle receiver is modified so as to receive the recoil lug. 
     In accordance with a second aspect of the invention, a new rear mounting screw is mounted into a rear portion of the rifle receiver. 
     In accordance with a third aspect of the invention, a new trigger is coupled to the original trigger via a pivotally engaged bar, and the excess portion of the original trigger is removed. 
     In accordance with a fourth aspect of the invention, the new trigger is disposed in front of the original trigger. 
     In accordance with a fifth aspect of the invention, an existing pivot pin is decreased in diameter to prevent pistol barrels from being coupled to the rifle receiver. 
     These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a an elevational profile view of the invention which is made in accordance with the principles of the presently preferred embodiment. 
     FIG. 2A is an elevational profile view of the unmodified rifle receiver of the prior art that is utilized in the present invention. 
     FIG. 2B is an elevational profile view of the rifle receiver of FIG. 2A after it has been modified to function as the receiver for a mid-grip high-powered pistol. 
     FIG. 3 is an elevational profile view of a rear portion of the pistol of the present invention, showing where mounting screws couple the mid-grip stock to the receiver. 
     FIG. 4A is an elevational profile view of the recoil lug of the presently preferred embodiment. 
     FIG. 4B is an elevational end view of the recoil lug of FIG.  4 A. 
     FIG. 5A is an elevational profile view of the new trigger assembly of the presently preferred embodiment. 
     FIG. 5B is an elevational top view of the new trigger assembly shown in FIG.  5 A. 
     FIG. 6 is a close-up and elevational profile view of the new trigger assembly installed on the modified rifle receiver of the presently preferred embodiment. 
     FIG. 7A is an elevational profile view of the barrel forearm lug, the forearm stock, and the barrel of the presently preferred embodiment. 
     FIG. 7B is an elevational top view of the barrel stock used in FIG.  7 A. 
     FIG. 7C is an elevational profile view showing how the forearm stock and the barrel pitch forward for the break-action rifle receiver. 
     FIG. 8 is an elevational profile view of an alternative embodiment of a trigger assembly that can be used with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings in which the various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. It is to be understood that the following description is only exemplary of the principles of the present invention, and should not be viewed as narrowing the claims which follow. 
     The present invention is the modification of an existing rifle receiver to create a mid-grip high-powered pistol. It is useful to understand the purpose of such a modification before addressing how this is accomplished. 
     One of the main problems in manufacturing a mid-grip high-powered pistol is the cost. Manufacturing costs are often very dependent upon the quantity of the item that is going to be produced. Speciality weapons such as a mid-grip high-powered pistol of the present invention have a limited market, and thus a purchaser is faced with the dilemma of paying more for this type of firearm when it is tooled to be manufactured. The inventor believed that a suitable low-cost rifle receiver might be capable of being modified at a cost that would be less than the cost of directly manufacturing the mid-grip high-powered pistol. The present invention is the culmination of that effort. 
     FIG. 1 is an elevational profile view of the presently preferred embodiment of the invention. A pistol  10  is shown having a mid-grip stock  12 , a portion of a rifle receiver  14  being visible, a barrel  16 , and a forearm stock  8 . To create this pistol, it is necessary to look at the individual components, and examine how they are assembled. 
     FIG. 2A is an elevational profile view of an unmodified rifle receiver  18  of the prior art, with the stock removed. It is noted that the rifle receiver  18  that was selected for this embodiment is a mass produced design, has a reliable performance record in the industry, and has a single shot action. The manufacturer of the rifle receiver  18  is New England Firearms of Massachusetts. However, it is an aspect of the invention that any appropriate rifle receiver can be used. What is important is that the rifle receiver be of sufficiently low cost such that making the modifications will result in a pistol that is less expensive to make than one which is tooled and manufactured directly. 
     As shown in the presently preferred embodiment of FIG. 2B, one of the modifications that is made to the rifle receiver  18  is to square off the concave rear portion  20  of the receiver relative to a top line  22  thereof. In this embodiment, a wedge-shaped portion  34  of the bottom edge of the receiver  14  is also removed. Not shown is a new rear mounting screw that is used to couple a shorter stock to the receiver  14 . The new rear mounting screw is coupled to an existing threaded hole  24 . 
     When adding a new shorter stock, the receiver  14  is glass bedded to the new stock to form a partial recoil area. Advantageously, this new configuration prevents the bottom rear area  34  from splitting the stock under heavy recoil. This design also shortens the length of the wood required behind the action of the receiver  14 . 
     In order to enable placement of the mid-grip stock  12  for the pistol and a new trigger, it is also necessary to remove a portion of the original trigger guard  26 , and a portion of the original trigger  28 . As much of the original trigger guard  26  should be removed as desired. However, a portion of the original trigger guard  26  is retained because it also functions as a spacer inside the rifle receiver. Therefore, the portion of the original trigger guard  26  that is outside of the rifle receiver is removed. This may not be necessary with all rifle receivers that could be modified to become a pistol. 
     The original trigger  28  is modified by cutting most of it off. The portion that remains is only left there so that there is something that can be attached to and still actuate it. In other words, the original trigger  28  still causes the receiver to fire, so a means has to be provided for actuating the original trigger  28  from the position of a new trigger. In this preferred embodiment, the means selected to do this requires that the original trigger  28  be cut off, slotted, and a hole disposed therethrough. Accordingly, the original trigger  28  needs to have a portion of metal removed so that a new extension bar can slide up into and between the remaining portions of the original trigger  28 . Finally, a hole  35  is drilled through the original trigger. The hole  35  passes through the new slotted portion in the original trigger  28 . More detail will be provided when the new trigger assembly is explained. 
     One of the most novel aspects of the invention is the addition of a recoil lug  32 . A recoil lug is not generally found on a pistol because typical pistol energy is not as great as that of a rifle. But the old rifle stock has been removed. Therefore, this feature was found to be critical in the performance of the invention because of the rifle energies that the pistol can deliver. Without it, the recoil is too great to allow for consistently accurate shooting. The greater recoil of the pistol could even result in harm to the user. 
     Not only was the addition of the recoil lug  32  necessary, but its placement along the receiver  14  is just as important. Specifically, the space between a recoil area at the end of the rifle receiver should be spaced as far from the recoil lug  32  as possible. The greater the space between them, the greater the reduction in recoil. 
     In the presently preferred embodiment, the recoil lug  32  is disposed as far forward as possible along the rifle receiver  14 , without interfering with a new trigger. In the presently preferred embodiment, the recoil lug  32  is disposed just behind a new trigger assembly. In this position, the recoil lug  32  also functions to guide an extension bar of the new trigger assembly, as will be shown. 
     In the presently preferred embodiment, the means for attaching the recoil lug  32  to the receiver  14  is going to require that the receiver be modified. In a present embodiment, a dove-tail is cut into the receiver  14  because it was a simple procedure. The recoil lug  32  is cut so as to fit into the dove-tail. However, it is envisioned that a preferred embodiment will couple the recoil lug  32  to the receiver  14  either by forging or welding. Likewise, the recoil lug  32  could also be attached by a screw. 
     Another modification of the receiver  14  is a pivot pin  36 . Specifically, the diameter of the new pivot pin  36  is changed. Changing the diameter has an important affect on the use of the pistol. The pistol will not be capable of interchanging rifle barrels for pistol barrels. This is important in order to prevent a user from creating a rifle that violates Federal laws. It is noted that the old receiver  18  has a pivot pin diameter of 0.375 inches. The new pivot pin  36  diameter can be increased or decreased to prevent rifle barrels from being coupled to the receiver  14 . The presently preferred embodiment increases the diameter of the new pivot pin  36  to 0.425 inches. Likewise, the diameter could also be decreased to 0.325 inches to achieve the same result. 
     A last modification to the receiver  14  is provided in order to couple a portion of the new trigger assembly to the receiver. Specifically, a slot  38  and a small hole  40  are drilled into the bottom of the receiver. The slot  38  is provided in order to enable the insertion of a new trigger. The hole  40  is disposed through the slot  38  so that the new trigger is free to pivot within the slot, while being held in place by a pin through the hole. 
     While modifications to the receiver  14  are obviously critical to the success of the present invention, there are other details of the pistol that must also be considered. These details include explaining  1 ) a method of mounting the mid-grip stock  12  to the receiver,  2 ) detail about the recoil lug,  3 ) the new trigger assembly, and  4 ) a method of mounting the forearm stock  8  to the barrel. 
     The presently preferred embodiment for mounting the mid-grip stock  12  to the receiver  14  comprises two attachment points. The first attachment point has been previously described as a new mounting screw  42 . FIG. 3 illustrates how a first mounting screw  42  is coupled to the threaded hole  24 . A hole  44  is also disposed in the end of the mid-grip stock  12  for the first mounting screw  42 . The hole  44  is also countersunk so that the first mounting screw  42  is hidden below the surface of the mid-grip stock  12 . The first mounting screw  42  is approximately 1.75 inches long, has a head with a thickness of 0.25 inches, and is ⅜ inch NFT. 
     The second attachment point between the mid-grip stock  12  and the receiver  14  occurs at the recoil lug  32 . Accordingly, the recoil lug  32  provides the added benefit of serving as an attachment point to the receiver  14 , without having to modify the receiver  14  even more. A small threaded hole  46  is cut into the bottom end of the recoil lug  32 . A hole  48  is also drilled through the mid-grip stock  12 . The hole  48  is countersunk to hide a second mounting screw  50  below the surface of the mid-grip stock  12 . The second mounting screw  50  is approximately 1.25 inches long, has a head that is approximately 0.125 inches thick, and is ¼ inch NFT. 
     FIGS. 4A and 4B provide more detail of the recoil lug  32 . The dimensions of the recoil lug  32  are provided for the presently preferred embodiment, but they may be modified as appropriate for a particular rifle receiver and trigger assembly. As shown in these figures, the recoil lug  32  is approximately 0.50 inches long, and 1.375 inches wide. The recoil lug  32  includes a threaded hole  46  for the second mounting screw  50 , and a hole  52  that is large enough for a trigger extension bar of the trigger assembly to pass through. Note that the recoil lug is tapered at approximately a 7° angle inwards on the front end, and is tapered at approximately a 2° angle inwards on either side. 
     The new trigger assembly of the present invention is simple and yet effective and reliable. FIGS. 5A and 5B show a profile view and a top view, respectively, of a trigger  54  and a trigger extension bar  56 . In FIG. 5A, the trigger  54  has a top portion  60  that slides into the slot in the bottom of the receiver  14 . A hole  62  enables a roll pin to be pivotally engaged to the receiver  14 . 
     Just beneath the top portion  60  is a slotted portion  64  of the trigger  54 . The slotted portion  64  is provided so that the trigger extension bar  56  can be coupled to the trigger  54 . A hole  66  through the slotted portion  64  enables the trigger extension bar  56  to pivotally engage the trigger  54  by inserting a roll pin therein. 
     The trigger extension bar  56  is generally round except at the ends, is approximately 3.75 inches long, and is bent at approximately a 7° angle near a midpoint thereof. The ends of the trigger extension bar are flattened in a vertical orientation so that they can slide into slots that are formed in the original trigger  28  and the new trigger  54 . Therefore, approximately 0.275 inches from the end that is coupled to the original trigger  28 , the trigger extension bar  56  is narrowed, with a hole  68  disposed therethrough. 
     FIG. 5B shows that the trigger extension bar  56  is approximately 0.175 inches in diameter, and that the new trigger  54  is approximately 0.30 inches wide. 
     FIG. 6 is provided as a cut-away elevational profile view to illustrate the operation of the new trigger assembly inside the mid-grip stock  12 . The trigger assembly is comprised of the trigger  54 , the trigger extension bar  56 , and the recoil lug  32 . As a finger pulls back on the trigger  54  which pivots in slot  38 , the components having roll pins pivot, while the trigger extension bar slides backwards through the recoil lug  32 , and pushes the original trigger  28  backwards, thereby discharging the pistol. 
     FIG. 7A is provided to illustrate the forearm stock  8 . It is important to realize that this forearm stock  8  is unique in that it is not an integral part of the mid-grip stock  12 . It is coupled directly to the pistol barrel. This arrangement is necessary so that when the barrel  16  is pivoted forwards to insert a round into the firing chamber, the forearm stock  8  slides along an outer edge of the mid-grip stock  12 . This pivoted forward position is shown in FIG.  7 C. 
     The forearm stock  8  is shown in cut-away to show how it is coupled to the barrel  16  along a length thereof. The means for attaching them together is a barrel forearm lug  72  that is disposed approximately 7.5 inches from the end of the receiver  14 . The purpose for varying a point of attachment of the barrel forearm lug  72  to the barrel  16  is to prevent the use of a rifle barrel with the pistol. 
     FIG. 7B is a top view of the forearm stock  8  that has been modified to function with the present invention. Specifically, note an extension  82  of the forearm stock  8 . This extension  82  is disposed up against the curved outer edge  84  (see FIG. 2B) of the receiver  14 . 
     The barrel forearm lug  72  has a threaded hole  74  therein. A third mounting screw  76  couples the forearm stock  8  to the barrel forearm lug  72  via the third mounting screw  76 . A hole  78  in the forearm stock  8  is countersunk to keep the end of the third mounting screw  76  from extending beyond the hole  78 . 
     It is noted that the barrel  70  used in the preferred embodiment is also from New England Firearms. Advantageously, it is noted that other pistol barrels can be substituted for the barrel shown in FIG.  7 . However, these other barrels must either have an attachment point at a same place along the barrel, or be modified by coupling an attachment at the same place. 
     It is also noted that the preferred barrel length extends up to fifteen inches. It is understood that a pistol can have a barrel whose length does not exceed  16  inches. Nevertheless, it has already been explained that the position of the barrel forearm lug  72 , and the new diameter of the pivot pin  36  are designed to prevent use of rifle barrels. 
     There can be many modifications to the presently preferred embodiment, all of which will result in a mid-grip high-powered pistol that utilizes the principles of the invention. For example, consider FIG.  8 . FIG. 8 shows another design of a trigger assembly that can be used in place of the preferred embodiment shown in FIGS. 5A and 5B. In the preferred embodiment, the extension bar  56  is separate from the trigger itself  54 . Furthermore, they pivot with respect to each other because of hole  66  and a pivot pin inserted therein. 
     In the alternative embodiment, the extension bar is made integral with or is coupled to the trigger so that they function as a single unit that does not pivot. Thus, this trigger would simply move back as a single unit against a trigger guard. While this action is not the same as a typical trigger that pivots, it would accomplish the same purpose, which is to actuate the original trigger. 
     It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. The appended claims are intended to cover such modifications and arrangements.