Abstract:
A bullpup assembly for converting an AR-15 type firearm having an AR-15 stock in unmodified assembly into a bullpup configuration. The bullpup assembly includes a frame body coupleable with the body of the firearm, the frame comprising a bullpup trigger, and the frame being configured to replace the AR-15 stock, and a trigger link coupled with the bullpup trigger and coupleable with a firearm trigger of the firearm, wherein actuation of the bullpup trigger actuates the firearm trigger via the trigger link.

Description:
[0001]    This application claims priority to U.S. Provisional Patent Application No. 61/513,744 filed on Aug. 1, 2011, the entirety of which is hereby incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Aspects of the present invention relate to AR-15 and similar type firearms, and more particularly an apparatus and method for converting AR-15 type firearms to bullpup configurations. 
         [0004]    2. Background 
         [0005]    Firearms with and without a bullpup configuration are well known for military and private use. Generally, conventional firearms include an elongated stock, also known as a buttstock, to which the barrel and firing mechanism are attached, that is held against one&#39;s shoulder when firing the gun. The stock provides a means for the shooter to firmly support the device and easily aim it. The stock also transmits recoil into the shooter&#39;s body. 
         [0006]    Bullpups are firearm configurations in which the action is located behind the trigger group and alongside the shooter&#39;s face, so there is no wasted space for the stock as in conventional designs. This permits a shorter firearm length for the same barrel length for improved maneuverability, and reduces weight. Thus, firearm purchasers often prefer the bullpup configuration over the conventional configuration. 
         [0007]    In the related art, firearms are generally manufactured to either have a conventional configuration or a bullpup configuration. Thus, one must decide whether to purchase a conventional or bullpup configuration, and converting an already manufactured conventional configuration firearm, in the related art, typically requires substantial reengineering by a professional gunsmith. Once converted, the bullpup configured firearm likewise is not easily converted back into a conventional configuration without substantial reengineering. Thus, there is a need in the art for an apparatus and method for converting a firearm from a conventional configuration to a bullpup configuration and converting back to a conventional configuration without substantially reengineering the firearm, such as by a professional gunsmith. 
         [0008]    In particular, the AR-15 and similar type model firearms are generally manufactured with a conventional configuration. Thus, there is a need in the art for apparatuses and methods for converting conventional AR-15 type firearms to bullpup configurations and converting back to conventional configurations without substantially reengineering the firearm, such as by a professional gunsmith. 
       SUMMARY OF THE INVENTION 
       [0009]    Aspects of the present invention provide, among other things, features for reconfiguring a conventional AR-15 type firearm to a bullpup configuration. 
         [0010]    Aspects of an example bullpup assembly include a bullpup frame securably engageable with a firearm. The bullpup frame includes a bullpup trigger and trigger link, wherein a first end of the trigger link is coupled to or otherwise interoperates with the bullpup trigger. The other end of the trigger link abuttably connects or otherwise interoperates with the original trigger of the firearm (also interchangeably referred to herein as the “firearm trigger”) so that actuation of the bullpup trigger actuates the firearm trigger. 
         [0011]    Aspects of an example bullpup configured firearm in accordance with aspects of the present invention include a firearm body, a firearm barrel, a firearm trigger, a bullpup frame securably engageable with the firearm, and a shoulder butt portion securable to the firearm body. The bullpup frame includes or assembleably operates in conjunction with a bullpup trigger and trigger link, wherein a first end of the trigger link is coupled to or otherwise interoperates with the bullpup trigger. The other end of the trigger link abuts the trigger of the firearm so that actuation of the bullpup trigger actuates the firearm trigger. 
         [0012]    Aspects of the present invention further provide methods for modifying a conventional AR-15 type firearm to a bullpup configuration. The method includes removing a stock and handle from a conventional configuration firearm and then securably engaging the bullpup frame to the disassembled firearm, such that actuation of a trigger of the lower bullpup frame actuates a trigger of the disassemble firearm. In addition, shoulder butt portion is secured to the firearm body. 
         [0013]    Additional advantages and novel features of various aspects of the present invention will be set forth in part in the description that follows, and in part will become more apparent to those skilled in the art upon examination of the following or upon learning by practice thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]    In the drawings: 
           [0015]      FIG. 1  shows a side view of an example AR-15 type firearm having a conventional configuration; 
           [0016]      FIG. 2  shows a side view the firearm of  FIG. 1  with selected components removed; 
           [0017]      FIG. 3  shows a perspective exploded view of a bullpup assembly in accordance with aspects of the present invention; 
           [0018]      FIG. 4  shows a perspective partial visible view of the frame of the bulipup assembly of  FIG. 3 ; 
           [0019]      FIG. 5  shows a side partial visible view of the frame of the bullpup assembly of  FIG. 3 ; 
           [0020]      FIG. 6  shows a side partial visible view of a modified firearm having a bullpup configuration in accordance with aspects of the present invention; 
           [0021]      FIG. 7  shows a perspective partial visible view of the modified firearm of  FIG. 6 ; and 
           [0022]      FIG. 8  shows a side partial visible view of the frame of an example bullpup assembly having an optional second handle, in accordance with aspects of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Aspects of the present invention include a bullpup assembly for an AR-15 type firearm, a bullpup configured AR-15 type firearm, and a method for converting a conventional AR-15 type firearm into a bullpup configured AR-15 type firearm. 
         [0024]      FIG. 1  shows a side view of an example AR-15 type firearm  10  having a conventional configuration, i.e., does not have a bullpup configuration. The firearm  10  includes a body  12 , a stock  14 , a handle  16 , a grip  18 , a barrel  20 , a firearm trigger  22 , a magazine  24 , a gas tube holder  26 , a sight  30 , a sight locking pin  31  for securing a portion of the sight, and other features known in the art. The stock  14  is attached to the main body  12  (e.g., via one or more screws and/or other attachment features), and in operation, is held against an operator&#39;s shoulder when firing the firearm  10 . The stock  14  allows the operator to firmly support the device and easily aim it. 
         [0025]      FIG. 2  shows a side view of an example AR-15 type firearm  50  having multiple components removed. In particular, the stock  14  and the handle  16  shown in  FIG. 1  have been removed. The other elements, including the body  12 , the firearm trigger  22 , the grip  18 , the gas tube holder  26 , the barrel  20 , the magazine  24 , and the sight  30 , including the sight locking pin  31 , remain. Generally, the mechanical parts of the firearm that contribute to firing operation remain operable in accordance with conventional operation. When the stock  14  is removed, one or more attachment features, such as an attachment screw receiving surface  32 , remains. In conventional assembly, as shown in  FIG. 1 , the attachment screw receiving surface  32  may have, for example, a threaded screw receiving opening, by which the stock  14 , having a corresponding opening for receiving a screw may be secured to the body  12 . 
         [0026]      FIG. 3  shows a perspective exploded view of a bullpup assembly  100 . More specifically,  FIG. 3  shows the elements of the bullpup assembly  100  before it has been assembled onto the firearm of  FIG. 2  The bullpup assembly  100  includes: 1) a bullpup frame  102  (also interchangeably referred herein as a frame body); 2) a trigger link assembly  105 , which includes a trigger link  106  and a bullpup trigger  108 , along with a firearm trigger engagement feature  104 ; and 3) a shoulder butt  116 . The bullpup frame  102  includes a hollow body  110  (also interchangeably referred herein as an interior cavity) integrally formed with a handle  112 , a trigger guard  114 , one or more sight locking pin receiving openings  120 , and an opening for receiving a screw or other securing mechanism for securing the bullpup frame  102  to the body of the firearm. 
         [0027]      FIG. 4  shows a perspective view of the bullpup frame  102 , where the body  110  is shown as transparent for clarity. As shown in  FIG. 4 , the bullpup trigger  108  may be located within the body  110 . Further, the bullpup trigger  108  may be linearly coupled within the body  110  via a coupling mechanism  108   a,  such as screw, a pin, or the like. The bullpup trigger  108  may also be coupled with the trigger link  106 , which extends though the body  110  to an attached firearm trigger engagement feature  104 . Thus, force imparted on the bullpup trigger  108  (e.g., linear action during firing) may be transferred via the trigger link  106  toward the opposite end of the trigger link  106  from the end of the trigger link  106  that is coupled with or otherwise interoperable with the bullpup trigger  108 . Also shown in  FIG. 4  is the location for an opening for receiving a screw or other securing mechanism, and a securing mechanism  118 , such as a screw. 
         [0028]      FIG. 5  shows a side view of the bullpup frame  102 , where the body  110  is shown as transparent for clarity. 
         [0029]      FIG. 6  shows a side view of an example AR-15 type firearm modified to a bullpup configuration, where the bullpup frame  102  is shown as transparent for clarity.  FIG. 7  shows a perspective view of the example firearm of  FIG. 6 . In particular,  FIGS. 6 and 7  show the disassembled firearm  50  of  FIG. 2  after it has been coupled with the bullpup assembly  100 .  FIGS. 6 and 7  show various elements that are included in  FIGS. 2 and 3 , in an assembled configuration. As shown in  FIGS. 6 and 7 , the bullpup frame  102 , including the bullpup trigger  108  and the trigger link  106 , is abuttably assembled with the lower portion of the disassembled firearm  50 . The upper surface outer edge of the bullpup frame  102  is shaped and sized so as to abut corresponding surface features of the firearm  50 , and the sight locking pin receiving openings  120  are located so as to allow a sight locking pin  31  to be inserted through the pin receiving openings  120  and the sight  30 , in order to partially secure the bullpup frame  102  to the firearm  50 . 
         [0030]    The trigger link  106  may extend within the hollow body  110  of the bullpup frame  102 , around the magazine  24  and/or magazine well, and operably engage the firearm trigger  22  via the firearm trigger engagement feature  104 . Because the trigger link  106  operably engages the firearm trigger  22  on one end and is operably engaged with the bullpup trigger  108  on the other end, motion of the bullpup trigger  108  produces corresponding motion of the firearm trigger  22  via the trigger link  106 , such as when the firearm is fired. 
         [0031]    In assembly, in addition to the sight locking pin  31  being inserted through the pin receiving openings  120  to secure a portion of the bullpup frame to the firearm  50 , the attachment screw receiving surface  32  is aligned with the opening for receiving a screw or other securing mechanism in the bullpup frame  102 , and the securing mechanism  118  is engaged through the opening in the bullpup frame  102  and into the threaded opening in the screw receiving surface  32 , in order to secure the bullpup frame to the firearm  50 . 
         [0032]    The bullpup frame may comprise any material suitable for use with a firearm. Of limited concern may be the heat produced within the barrel of a gun during firing. Thus, the material chosen for some portions of the bullpup frame may need to retain form and properties under high heat. In some variations, the frame or portions of the frame may comprise a hard plastic having a high melting point or a metal. Optionally, the bullpup frame may further comprise one or more heat shielding elements that may be located within the bullpup frame or that may be integral with one or both of these frames. Such heat shielding elements may comprise metal shielding, such as firearm grade aluminum, that is located within the bullpup frame at appropriate locations (e.g., near the barrel). 
         [0033]      FIG. 8  shows a side view of a similar example bullpup frame  150  to the bullpup frame  102  shown in  FIG. 5 , with the body  110  being shown as transparent for clarity. The bullpup frame  150  of  FIG. 8  further includes a second handle  130 . The second handle  130  may optionally be retractable, such as via pivoting about pivot point  131  (e.g., a pin) and lockable in extended and/or retracted position, such as via locking feature  132  (e.g., a locking pin biased to extend to an extending position through a locking opening in the handle  130  or body  110 , and selectably retractable, such as by depressing the locking pin through the locking opening). 
         [0034]    A method for assembling the modified firearm having a bullpup configuration will now be described. Starting with the conventional firearm  10  of  FIG. 1 , the stock  14  and the handle  16  are removed. The stock  14  and the handle  16  may be easily removed without the need for a gunsmith, for example, because the elements may be secured to the body  12  via screws or other securing features, and mating surfaces. For the stock  14 , the operator may simply unscrew the stock  14  from the body  12  and/or otherwise disconnect or remove any securing features. Similarly, the operator may remove the handle  16  by removing the securing feature that attaches the handle  16  to the attachment screw receiving surface  32 . Once the stock  14  and the handle  16  have been removed, the conventional AR-15 type firearm is in the state shown in  FIG. 2 . 
         [0035]    Next, the operator proceeds to attach the bullpup frame  102  ( FIGS. 3 to 5 ) to the firearm of  FIG. 2 . The bullpup frame  102  may be abuttably placed against the bottom portion of the firearm  50 , as shown in  FIGS. 6 and 7 . As shown in  FIGS. 6 and 7 , a portion of the body  12 , the firearm trigger  22 , magazine  24 , and a portion of the barrel  20  of the firearm  50  may be located within the bullpup frame  102 . The pin receiving openings  120  may be aligned with corresponding openings in the sight  30 , and the sight locking pin  31  may be inserted through the pin receiving openings  120  to secure a portion of the bullpup frame  102  to the firearm  50 . The securing mechanism  118  may be aligned with the mating piece  32  and the trigger link  106  may be aligned with the firearm trigger  22 . The location for the opening in the bullpup frame for receiving the securing mechanism is aligned with the threaded opening in the attachment screw receiving surface  32 , and a securing mechanism  118  is then engaged with the threaded opening to secure to further secure the bullpup frame  102  to the firearm  50 . 
         [0036]    After the above steps are taken, the bullpup configured AR-15 type firearm shown in  FIGS. 6 and 7  is completed. Whenever the operator desires to return the AR-15 type bullpup configuration back to a conventional AR-15 type configuration, the user need only reverse the above steps. One or all of the above steps of assembling or disassembling the bullpup configuration may be carried out so as to avoid the need for machining or other assistance by a professional gunsmith. Rather, a relatively unskilled operator need only screw/unscrew and assemble the relevant elements of the firearm. As shown in  FIGS. 1 ,  2 ,  6  and  7 , the complex functionality of the firing mechanism remains unaltered when the firearm is in the conventional state or the bullpup state. Thus, the above-described apparatus and method allows a firearm purchaser to easily and safely modify the firearm without the assistance of an expert. 
         [0037]    Example aspects have been described in accordance with the above advantages. It will be appreciated that these examples are merely illustrative of aspects of the invention. Many variations and modifications will be apparent to those skilled in the art.