Abstract:
A firearm adapter for AM180 .22 caliber cartridge drums includes: a tower adapted to engage with a cartridge-receiving mechanism of the firearm; a plate having a first surface to releasably engage with and retain the cartridge drum in a plane generally parallel to the plate, and a second surface to engage with and retain the tower in an orientation at a substantial angle to the plane of the plate; and an aperture in the plate that aligns with a feeding aperture in the drum and the tower so as to transport the cartridge from the drum to the tower.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims benefit of priority from U.S. Provisional Application No. 61/102,114, filed Oct. 2, 2008, which is incorporated herein by reference in its entirety, and U.S. Provisional Application No. 61/105,222, filed Oct. 14, 2008, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to firearms, and more specifically, to a firearm cartridge drum adapter. 
         [0003]    The American 180 (AM180) is a firearm that fires .22 long rifle cartridges from a drum (the AM180 drum), also called a pan magazine. Opposite sides of the base of the AM180 drum have extensions, which are inserted into magazine guides on the AM180, so that the AM180 generally holds the drum on top of the barrel, parallel to its barrel (e.g. horizontally) , with the cartridges feeding in a gravitational (downward) manner. 
         [0004]    The AM180 drum utilizes an external winding mechanism, which includes a spring that causes components of the drum to rotate when the AM180 is fired. As the drum rotates, the cartridges inside the drum are forced out of an opening in the drum. The cartridges are stored nose-in, in the plane of the drum, so that when the drum is horizontal, the cartridges are horizontal and are fed out of the opening in a horizontal orientation. 
         [0005]    Non-AM180 firearms accept .22 caliber cartridges through a removable clip or box magazine that feeds the cartridges in a column (e.g. vertically for the HK or AR15/M16). These may be called stick-type magazines. 
         [0006]    There are currently no available .22 caliber drum adapters that adapt the AM180 drum to non-AM180 firearms. 
         [0007]    As can be seen, there is a need for an adapter to utilize a high capacity cartridge drum designed for one firearm, such as the AM180 drum, with other firearms. 
       SUMMARY OF THE INVENTION 
       [0008]    In one aspect of the present invention, a device utilizing a firearm adapted to receive a cartridge and a drum adapted to hold the cartridge, the drum having a first aperture, a first extension adjacent the first aperture, and a second extension opposite the first extension, the drum adapted to transport the cartridge out of the drum through the first aperture, includes: a plate having a second aperture, the plate adapted to releasably engage with the drum so that the first aperture aligns with the second aperture, the plate having a first section and a second section; a first hook on the first section of the plate, adapted to engage with the first extension of the drum; and a second hook slidably attached to the second section of the plate, adapted to engage with the second extension of the drum, the second hook cooperating with the first hook so to as to releasably retain the drum; wherein the device engages with the drum, retains the drum, and aligns the first aperture of the drum with the second aperture, so that the cartridge is transported out of the first aperture, through the second aperture, and to the firearm so that the firearm receives the cartridge. 
         [0009]    In another aspect of the present invention, a device utilizing a firearm, a cartridge, and a drum, includes: a tower adapted to engage with a cartridge-receiving mechanism of the firearm; a plate having a first surface to releasably engage with and retain the cartridge drum in a plane generally parallel to the plate, and a second surface to engage with and retain the tower in an orientation at a substantial angle to the plane of the plate; and an aperture in the plate that aligns with a feeding aperture in the drum and the tower so as to transport the cartridge from the drum to the tower. 
         [0010]    In yet another aspect of the present invention, method of providing a cartridge from a drum to a firearm, includes: providing a plate having an aperture, a first retaining member, and a slidable second retaining member; retaining a first extension of the drum with the first retaining member; retaining a second extension of the drum with the second retaining member; receiving the cartridge from the drum into the aperture; and transporting the cartridge from the aperture to the firearm; thereby providing the cartridge from the drum to the firearm. 
         [0011]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  depicts an exploded view of an embodiment of the present invention; 
           [0013]      FIG. 2A  depicts a top view of an embodiment of an adapter plate assembly according to the present invention; 
           [0014]      FIG. 2B  depicts a side view of an embodiment of an adapter plate assembly according to the present invention; 
           [0015]      FIG. 2C  depicts a front view of an embodiment of an adapter plate assembly according to the present invention; 
           [0016]      FIG. 2D  depicts a rear view of an embodiment of an adapter plate assembly according to the present invention; 
           [0017]      FIG. 3  depicts an embodiment of the present invention for a Heckler and Koch (HK) G3/91/51 firearm modified for .22 caliber cartridges; 
           [0018]      FIG. 4  depicts an embodiment of the present invention in use with an AM180 drum on an HK G3/91/51 firearm modified for .22 cartridges; 
           [0019]      FIG. 5  depicts an embodiment of the present invention for an AR15/M16 firearm modified for .22 cartridges; and 
           [0020]      FIG. 6  depicts an embodiment of the present invention in use with an AM180 drum on an AR15/M16 firearm modified for .22 cartridges. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0022]    Various inventive features are described below that can each be used independently of one another or in combination with other features. 
         [0023]    Broadly, an embodiment of the present invention generally provides a drum adapter to adapt various firearm magazines to utilize a drum magazine. An embodiment may allow the AM180 .22 caliber cartridge drum to be utilized by firearms designed to utilize only low capacity feeding devices. Alternate embodiments may allow other high capacity cartridge drums to be utilized by firearms designed to utilize only low capacity feeding devices. 
         [0024]    An embodiment of the present invention includes a drum adapter plate assembly and interchangeable cartridge towers that allow the unit to be utilized in various firearms and other applications. The drum adapter plate assembly includes a stainless steel cut and formed flat plate shaped to fit into a slot on top of a cartridge drum with a shaped slot cut to allow cartridges from the drum to feed up through the adapter plate. In the preferred embodiment, the adapter plate is shaped to fit into a slot on top of an American 180 (AM180) .22 caliber cartridge drum. 
         [0025]    As depicted in  FIG. 1 , an embodiment  10  may include an adapter plate  12 , a bridge block  14  attached below the plate, and a slide latch  16  slidably attached above the plate. The bridge block  14  extends down and in, and acts like a hook to engage with an extension or protrusion on the drum (not shown in  FIG. 1 ). The slide latch  16  has a section that extends below the plate and also extends down and in to act like a second, anterior hook to engage with a second extension on the drum, opposite the first extension. A spring retainer  18  supports the drum and holds a tension spring  20  for the slide latch  16 . The spring retainer  18  may have batwing flanges on either side to stabilize the drum and keep the drum parallel to the adapter plate  12 . Two button head cap screws  22  fit through two slots in the slide latch  16 , to slidably retain the slide latch  16  to the adapter plate  12 . A pin  24  holds one end of the spring  20 , which extends through a hole in the slide latch  16 , and a second pin holds the other end of the spring against indentations in the far side of the spring retainer  18 . Two bolts or screws  26  attach the spring retainer  18  to the adapter plate  12 . Two dowel pins  28  fit through the adapter plate  12  and extend into two holes in the top of the drum for stability. 
         [0026]    As depicted in the embodiment of  FIG. 1 , an embodiment may include a Heckler and Koch® (HK) cartridge tower  34 , adapted to work with an HK G3/91/51 firearm modified for .22 caliber cartridges, or an AR15/M16 cartridge tower  36 , adapted to work with an AR15/M16 firearm modified for .22 caliber cartridges. Two short screws  30  extend through the adapter plate  12  to retain the front part of one of the cartridge towers  34 ,  36 , and a long screw  32  extend through the bridge block  14  and the adapter plate to retain the rear part of the cartridge tower. The adapter plate  12  has an aperture  48  which receives the cartridge from the drum and provides the cartridge to the tower  34 ,  36 . 
         [0027]    As depicted in  FIGS. 2A ,  2 B,  2 C, and  2   d,  an embodiment of the adapter plate assembly  40  may include the adapter plate  12 , the bridge block  14 , the slide latch  16 , the spring retainer  18 , the tension spring  20 , the slide latch screws  22 , the pin  24  for the spring  20 , the spring retainer screws  26 , and the aperture  48  for the cartridges. In an embodiment, the cartridge towers  34 ,  36  may be interchangeable with the same adapter plate assembly  40 . In the preferred embodiment, the drum is an AM180 .22 caliber cartridge drum. 
         [0028]      FIG. 3  depicts an embodiment of an adapter plate assembly  40  with an HK cartridge tower  34 .  FIG. 4  depicts an HK G3/91/51 firearm modified for .22 cartridges  42  with an adapter plate assembly  40 , HK cartridge tower  34 , and an AM180 drum  44 .  FIG. 5  depicts an embodiment of an adapter plate assembly  40  with an AR15/M16 cartridge tower  36 .  FIG. 6  depicts an AR15/M16 firearm modified for .22 cartridges  46  with an adapter plate assembly  40 , AR15/M16 cartridge tower  36 , and an AM180 drum  44 . 
         [0029]    In the embodiments of  FIGS. 3 ,  4 ,  5 , and  6 , the main axis of the tower is at an angle to the plane of drum, which is preferably 84 degrees, but which may be 75 to 90 degrees. 
         [0030]    An embodiment of the present invention may include: a molded batwing plate for support and attachment of a roll pin that holds the spring for the anterior fastening hook; a spring which is attached to the anterior fastening hook, which latches onto and secures the front half of the drum to the drum adapter; two roll pins, which fasten the spring to the batwing and to the fastening hook latch; two dowel pins, which fit through the adapter plate and extend into two holes in the top of the drum for stability; and a contoured, hook-shaped, slotted metal piece, which attaches by machine screws in the slot to the plate. This allows the hook to move forward and back under spring resisted manual pressure to allow the hook to grab an extension on top of the AM180 drum and hold it securely and then release it as desired. The pressure to move and hold this hook is by the attached spring. This hook extends over the top of the adapter plate to the underneath side. An embodiment may include two screws that securely mount and hold the batwing assembly to the adapter plate; molded rear attachment endpiece which fits on the underneath side of the plate and is slotted to grasp and hold a small tab on the rear of the AM180 drum. This tab is held onto the plate by machine screws which fasten into the adapter plate. An embodiment may include two machine screws, which hold the molded rear endpiece to the adapter plate; two machine screws, which fasten the hook assembly to the adapter plate; and three holes machined into the adapter plate for attachment of the interchangeable cartridge towers. 
         [0031]    In an embodiment, the components attach to the adapter plate and allow the firm grasping and securing of the AM180 drum, which allows the drum to feed its cartridges up through the drum adapter plate and into an interchangeable firearm specific cartridge tower. This allows the .22 cartridges from the drum to feed out of the drum, through the adapter plate and up the firearm-specific magazine body into the .22 caliber firearm or into the centerfire caliber firearm containing a .22 caliber conversion, to function utilizing the full capacity of the drum. 
         [0032]    An embodiment of the drum adapter plate assembly allows a physical connection to the drum and a functional connection. It allows the drum to function in its normal capacity by holding and expelling the drum&#39;s contained cartridges, and the adapter plate assembly combined with a specific firearm adapter body allows the transference of the cartridges to a firearm for which the drum may not have been initially designed. Many different adapter bodies could allow a drum to be utilized in various firearms for which it was never designed nor able to function with directly. 
         [0033]    An embodiment of the parts may be made from all machined parts, or a mix of machined and molded. Parts may be cut and molded and shaped to exacting dimensions and assembled. The interchangeable adapter towers can be molded as a one piece item or can me molded or machined as a 2 piece item. Existing magazine bodies can be cut and modified to fit on the adapter plate assembly. 
         [0034]    In an embodiment, the components allow a an America 180 drum filled with .22 caliber cartridges to be held securely and feed through the adapter so that the converted firearm can use the drum&#39;s increased capacity. The drum rotates as it is feeding rounds up the adapter. The drum may include a winder that may be available from the drum manufacturer. Interchangeable towers may include towers for an HK G3/91/51, AR15/M16 , Uzi(R), M11, M10, Sten, Stemple, Swedish K, or any other centerfire firearm utilizing a .22 caliber conversion kit or other .22 firearms by design such as a Ruger(R) 10/22. 
         [0035]    An embodiment may include an outer modified magazine body that allows the unit to be held in the host weapon without modification to the firearm. Blocks may hold the inner modified magazine in position inside the outer magazine. The inner and outer magazine bodies may be shortened and angled at the same angle so that the bottoms of the inner and outer magazine bodies are level with each other. A piece of aluminum or other material is cut and shaped to fit across the top of an drum and a relief is cut in one end to allow cartridges from the drum to feed up through the adapter into the modified magazine. Attached to one end of the plate is a contoured piece of aluminum or other metal with a slot in it to allow the small tabbed end of the drum to be held securely in place. At the other end of the bar is a hooked piece of aluminum, which is a nook that rests on the plate. It has a slotted channel in which screws allow it to travel back and forth the length of the slot. The hook extends down under the plate and fastens the other tabbed end of the drum into the plate and holds it in place. The slotted piece has a spring attached to it. The other end of the spring is attached to an L bracket that is held onto the plate with screws. The spring is protected in an aluminum or other metal channel the length of the spring that is attached to the plate with screws. This channel has bat-shaped wings that extend over the drum for approximately 2 inches to help steady the rotating drum. All of this plate assembly is fastened to the magazine blocks with pins and screws. 
         [0036]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.