Patent Publication Number: US-8117954-B1

Title: Firearm modification kit

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to ordnance and, more particularly, to charging mechanisms for guns. 
     BACKGROUND OF THE INVENTION 
     The Kalashnikov assault rifle, better known as the AK-47, and its variants comprise one of the largest groups of firearms on earth. It has been estimated that over 90 million of these firearms have been produced in dozens of countries since their introduction in the Soviet Union in 1946. Developed primarily as a military weapon, the AK-47 became famous for its simplicity of operation and reliability in extreme conditions of use. Because of its mild recoil, the AK-47 has the capability of delivering effective full-automatic fire at a range of 300 meters. 
     The AK-47 has a few problems that make it less than optimal for use as a weapon of war. One of these, a lack of means to hold the bolt open after the last round is fired from its magazine, was solved by the bolt locking mechanism described in my previously issued U.S. Pat. No. 7,261,029. A currently unresolved problem, however, involves the construction of an AK-47 for the exclusive operation of either a right- or a left-handed user. Thus, a right-handed user can have a difficult time aiming and firing a left-handed AK-47 (made by cutting the charging handle from it normal spot on the right side of a bolt carrier and welding it onto the left side of the bolt carrier) and a left-handed user can have a tough time operating a right-handed AK-47. 
     For optimum shooting performance, it is important that a user hold an AK-47 by the pistol grip with his strong hand and while looking at the intended target through the sights. (The strong hand of a right-handed user is his right hand, and the strong hand of a left-handed user is his left hand.) To initiate the firing of an AK-47, a bullet is driven from a loaded magazine into an empty chamber by: grasping the AK-47 by the pistol grip with the strong hand, pulling the charging handle to the rear with the weak hand, and then releasing the charging handle. If the configuration of an AK-47 causes a user to hold the pistol grip with his weak hand, the charging process is slowed and a steady aim is lost. 
     SUMMARY OF THE INVENTION 
     In view of the problems associated with right- and left-handed variants of the AK-47 assault rifle, it is a principal object of the present invention to provide a kit that permits a user to readily draw the bolt carrier of an AK-47 rearwardly with either his right hand or his left hand thereby making an AK-47 carrying the kit ergonomic. 
     It is another object of the present invention to provide a kit of the type described that replaces the conventional receiver cover and bolt carrier of an AK-47. The kit can be incorporated into an AK-47 at the time of its manufacture or it can be supplied as an aftermarket product that a user can install. Installation requires just a few moments to accomplish and requires no tools. 
     Still another object of the invention is to provide a kit of the type described that will not interfere with normal operation of an AK-47 or a variant thereof. Thus, a firearm equipped with the kit will function normally except that reloading is simplified and speeded-up by permitting a user to move the bolt carrier rearwardly with either his right hand or his left hand as desired. 
     It is an object of the invention to provide improved features and arrangements of features in a kit for the purposes described that is lightweight in construction, inexpensive to manufacture, and fully dependable in use. 
     Briefly, my kit achieves the intended objects by featuring a receiver cover and bolt carrier of improved construction. The receiver cover includes a pair of retaining fins that are affixed to the bottom of an arched crown. One of the retaining fins is provided with a longitudinal slot. A guide track is affixed to the retaining fin having the slot. The guide track has a pair of retaining flanges disposed on opposite sides of the slot. A charging handle assembly is secured to the guide track and includes a slide that is slidably engaged with the retaining flanges and is adapted to move along the length of the guide track. An auxiliary charging handle is affixed to, and projects outwardly from, the slide. An engagement pin is affixed to, and projects inwardly from, the slide. The engagement pin extends through the slot so as to engage a catch projecting from the bolt carrier. 
     The foregoing and other objects, features, and advantages of my kit will become readily apparent upon further review of the following detailed description of the kit illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       My firearm modification kit can be more readily described with reference to the accompanying drawings, in which: 
         FIG. 1  is an exploded perspective view of a firearm modification kit in accordance with the present invention. 
         FIG. 2  is a top view of the firearm modification kit of  FIG. 1  with portions broken away to reveal details of the kit. 
         FIG. 3  is a top view of the action cover of the kit showing the pivoting motion of the auxiliary charging handle. 
         FIG. 4  is a cross-sectional view of the action cover taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is an enlarged view of the circled portion of  FIG. 4 . 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the accompanying drawings. 
     DETAILED DESCRIPTION OF THE FIREARM MODIFICATION KIT 
     Referring now to the FIGS., a firearm modification kit in accordance with the present invention is shown generally at  10 . Kit  10  includes a receiver cover  12  and a bolt carrier  14  of improved form. Kit  10  is installed within an AK-47 assault rifle, or variant thereof, hereinafter referred to as a “firearm” and, after installation, becomes an integral part of the firearm. A variant of an AK-47 is described in my U.S. Pat. No. 7,261,029, issued Aug. 28, 2007, which is incorporated herein for its description of a firearm adapted for use with kit  10 . 
     Receiver cover  12  is elongated and arch-shaped, being adapted to snugly, yet slidably, enclose bolt carrier  14  therein. A crown  16 , having a configuration resembling that of an inverted “U”, defines the top of the arch. A pair of retaining fins  18 ,  20  is affixed to the bottom of crown  16  and defines the bottom of the arch. Each of fins  18 ,  20  has an upper portion  22 ,  24  that extends outwardly and downwardly from a respective one of the opposed sides of crown  16  to provide clearance for bolt carrier  14 . Each of fins  18 ,  20  also has a lower portion  26 ,  28  that extends downwardly from the bottom of its associated, upper portion  22 ,  24  for engaging the top of the firearm receiver. A back wall  30  closes the rear portion of the arch and is affixed to crown  16  as well as upper portion  22 ,  24  and lower portion  26 ,  28  of both retaining fins  18 ,  20 . 
     Receiver cover  12  is provided with a number of openings. An elongated slot  32  extends longitudinally along the retaining fin  20  on the left side of receiver cover  12 . Specifically, slot  32  is located midway between the top and bottom of upper portion  24 . Slot  32  extends from a forward point adjacent the forwardmost position of travel of the base block  34  of bolt carrier  14  (described more fully hereinbelow) in a firearm receiver to a rearward point adjacent the rearwardmost position of movement of the front of base block  34  in the receiver. A rectangular hole  36  is also provided in the center of back wall  30  for receiving a recoil spring base. 
     A guide track  38  is affixed to retaining fin  20 . Guide track  38  has an elongated, base plate  40  that is positioned flush against the upper portion  24 . Base plate  40  has a longitudinal slot  42  therein that is dimensioned and positioned so as to be coextensive with slot  32 . Base plate  40 , thus, serves to reinforce retaining fin  20  in the area around slot  32 . Affixed to the opposite sides of base plate  40  is a pair of retaining flanges  44  that extends outwardly from the base plate  40  so as to terminate at free ends remote from retaining fin  20 . Each of the retaining flanges  44  tapers in terms of its width such that it is widest at its free end and narrowest along its connection to base plate  40 . The taper results in retaining flanges  44  both overhanging base plate  40  along their lengths and defining a pair of opposed grooves as at  46 . 
     A charging handle assembly  48  is affixed to guide track  38 . Assembly  48  includes a slide  50  that is selectively moved in grooves  46  along the length of guide track  38  and an auxiliary charging handle  52  that is pivotally secured to slide  50 . When not needed, auxiliary charging handle  52  can be pivoted to a stowage position against receiver cover  12  to facilitate the easy handling and transport of a firearm. 
     Slide  50  engages guide track  38  and has an elongated guide body  54  that is positioned between retaining flanges  44  of guide track  38 . Affixed to the opposite sides of guide body  54  is a pair of retaining arms  56  that extends from the guide body  54  so as to terminate at free ends adjacent grooves  46  in guide track  38 . One of a pair of retaining fingers  58  is affixed to the free end of each of retaining arms  56 . Each of the retaining fingers  58  projects outwardly from a respective one of the retaining arms  56  and into a respective one of grooves  46 . Retaining fingers  58  are adapted for slidable movement in grooves  46 . 
     Slide  50  also includes an engagement pin  60  that is affixed to the bottom of guide body  54 . Engagement pin  60  extends inwardly from guide body  54  and through slots  32 ,  42 . Pin  60 , then, projects inwardly from the upper portion  24  of fin  20  and is adapted to both slide within slots  32 ,  42  and engage catch  62  of bolt carrier  14 . Pin  60  engages the front and rear ends of slots  32 ,  42  and serves as a stop against the continued movement of slide  50  from guide track  38 . 
     Slide  50  further includes a handle retaining tab  64  that is affixed to the top of guide body  54 . Handle retaining tab  64  projects outwardly from guide body  54  away from guide track  38 . Auxiliary charging handle  52  is pivotally secured to handle retaining tab  64 . 
     Auxiliary charging handle  52  includes a handle body  66  from which a pair of handle retaining fins  68  projects. Retaining fins  68  are respectively pivotally affixed to the top and bottom of handle retaining tab  64  by means of a pivot pin  70 . Handle body  66  tapers toward its outer, free end  72  that, when handle  52  is pivoted fully toward guide track  38 , is located a small distance  74  from upper portion  24  of retaining fin  20  so that a finger of a user can easily pivot handle  52  outwardly. When pivoted outwardly, handle body  66  abuts against retaining tab  64  to limit the range of pivoting motion of auxiliary charging handle  52  to about 90°. 
     Bolt carrier  14  moves a bolt within a receiver of a firearm. Bolt carrier  14  includes a base block  34  having longitudinal grooves  74  in its opposite sides for slidably engaging carrier guides in the receiver. A longitudinal bore  76  passes through base block  34  between longitudinal grooves  74  and is sized to receive the firearm bolt. A tubular sleeve  78  is affixed to the top of base block  34  and extends forwardly from base block  34 . Sleeve  78  receives a recoil spring and a spring guide within its confines. Beneath sleeve  78  and forwardly of bore  76 , bolt carrier  14  is provided with a slotted guideway  80  that receives a stud extending from the bolt. A primary charging handle  82  is affixed to the right side of guideway  80  and projects laterally from guideway. Charging handle  82  reciprocates outside of the receiver when the firearm is fired. 
     A catch  62  projects from the left side of bolt carrier  14  for selective engagement with engagement pin  60 . As shown, catch  62  has a configuration resembling that of a reversed “L”. Catch  62  has a horizontal member  84  that is affixed to both the front and top of base block  34 . Catch  62  also has a vertical member  86  that projects upwardly from the rear of horizontal member  84  and flush with tubular sleeve  78  to which vertical member  86  is affixed. Catch  62  is made by integrally casting it with the remainder of bolt carrier  14  or by adding it later by means of penetrating fasteners, welding or brazing. 
     Use of kit  10  is straightforward. First, bolt carrier  14  and receiver cover  12  are substituted for corresponding parts within a firearm in the usual manner. Next, assuming that a left-handed user wishes to easily discharge the firearm, a bullet is driven from the firearm&#39;s loaded magazine and into the empty chamber by: grasping the firearm&#39;s pistol grip with his left hand, pulling auxiliary charging handle  52  to the rear with his right hand, and, then, releasing auxiliary charging handle  52 . The firearm&#39;s spring-loaded action then returns charging handle  53  to its original, forward position at the front of guide track  38 . (Handle body  66  can, if desired, be manually pivoted toward fin  20  for stowage and subsequent use.) As auxiliary charging handle  52  is pulled backwardly, engagement pin  60  grasps vertical member  86  of catch  62  of bolt carrier  14  and draw&#39;s bolt carrier  14  rearwardly such that the action of the firearm is caused to chamber a bullet. The entire process of chambering a bullet requires only moments to complete and can be achieved without the left-handed user either taking his eyes away from his intended target or aiming the firearm away from an intended target. 
     Kit  10  is intended to accommodate the use of a folding firearm stock and side-mounted optics since charging handle assembly  48  does not reciprocate with bolt carrier  14  when the firearm is discharged. Perhaps, with side-mounted optics, only the primary charging handle  82  need be employed. Kit  10 , of course, allows a user to charge the firearm with either the right or left hand. 
     While kit  10  has been described with a high degree of particularity, it will be appreciated by individuals having experience with firearms that modifications can be made to kit  10 . For example, auxiliary charging handle  52  need not be made to pivot, but could be integrally formed with the balance of slide  50 . Furthermore, by modifying engagement pin  60  so as to hit the front edge of base block  34 , it is possible to eliminate catch  62 . Catch  62 , however, does provide a strong junction between receiver cover  12  and bolt carrier  14 . Thus, it must be understood that my invention is not limited merely to kit  10 , but rather it encompasses any and all kits within the scope of the following patent claims.