Abstract:
A magazine for a firearm is provided. The magazine includes a first wall and a second wall coupled to the first wall to define an enclosure. A first projection extends from a first portion of the first wall, a first end of the first projection being adjacent an end of the first wall, the first projection having a first angled surface opposite the first end. A second projection extends from a second portion of the second wall, a second end of the second projection being adjacent the first end, the second projection having a second angled surface arranged opposite the first angled surface.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates to a magazine for a firearm and in particular to a magazine for a firearm with increased reliability and reduced need for lubrication. 
         [0002]    Firearms having multi-round capabilities typically utilize an interchangeable magazine that holds a predetermined number of ammunition cartridges. Users typically preload several magazines, so that as a magazine becomes depleted during use, the user can quickly exchange the empty magazine with a full one. This allows the user to quickly resume using the firearm with minimal downtime. Magazines typically have a number of sizes, such as magazines holding 10 cartridges, 20 cartridges or 30 cartridges, for example. 
         [0003]    Magazines have several components, such as a magazine box that holds the cartridges and a follower that moves the cartridges into the firearm receiver. The follower is typically arranged in the magazine box and is biased by a spring towards the firearm receiver. The pressure of the spring is transferred to the cartridges, which ultimately moves a cartridge into the firearm receiver during operation. One issue that arises is the cartridge misfeeding, particularly with the first cartridge in the magazine. When this occurs, the cartridge becomes stuck partially out of the magazine when the buffer spring in the receiver is unable to overcome the frictional forces on the cartridge. The jamming of the cartridge prevents the firearm from being operated. It should be appreciated that the jamming of the magazine may greatly slow down the usage of the firearm by the user. 
         [0004]    To alleviate the misfeed of the cartridge, it is typically recommended that the firearm be cleaned and lubricated frequently. Lubrication of the firearm receiver has been found to reduce the frequency of jamming. United States Government qualification testing for new magazines requires that a firearm be able to fire four consecutive magazines without further lubrication before a misfeed occurs. 
         [0005]    While existing magazines for firearms are suitable for their intended purpose, there remains a need for improvements, particularly in increasing the reliability of a firearm and reducing or eliminating the requirement for frequent cleaning and lubrication to prevent ammunition cartridge jamming in the receiver. 
       SUMMARY 
       [0006]    Briefly stated, a magazine for a firearm comprises a first wall and a second wall coupled to the first wall to define an enclosed rectangular cavity. A curved first projection extends from a first portion of the first wall. The end of the first projection is adjacent an end of the first wall. The first projection has a first angled surface opposite the first end. A curved second projection extends from a second portion of the second wall. The end of the second projection is adjacent the first end. The second projection has second angled surface arranged opposite the first angled surface. 
         [0007]    The first projection includes a first edge arranged substantially parallel to the first wall. The first projection includes a second edge arranged substantially parallel to the second wall. The first edge and the second edge define a first opening into the enclosed rectangular cavity. A second opening in the enclosed rectangular cavity is defined by the first wall and the second wall and is positioned adjacent the first opening. The second opening is larger than the first opening. 
         [0008]    The first angled surface and the second angled surface define a transition opening between the first opening and the second opening. The first angled surface and the first edge define a first point of intersection. The first point of intersection is about 0.785 inches from the first end. The second angled surface and the second edge also define a second point of intersection. The second point of intersection is about 1.050 inches from the second end. 
         [0009]    In one embodiment, the first wall, second wall, first projection and second projection are made from aluminum. Alternatively, the first wall, second wall, first projection and second projection are made from steel. In another embodiment, the first wall, second wall, first projection and second projection are made from plastic. 
         [0010]    In one embodiment, a magazine for a firearm comprises a first wall having a first end with a first portion and a second portion. The first portion has a first projection and curves about 90 degrees relative to the plane of the first wall. The first projection has a first edge that is substantially parallel to the first wall and a first angled surface extending between the first edge and the second portion. A second wall is coupled to the first wall to define a parallelepiped-shaped container. The second wall has a second end adjacent the first end. The second wall has a third portion adjacent the first portion and a fourth portion adjacent the second portion. The third portion has a second projection that curves about 90 degrees relative to the plane of the second wall and towards the first projection. The second projection has a second edge that is substantially parallel to the first edge and a second angled surface extending between the second edge and the fourth portion. 
         [0011]    The first portion and the third portion define a first opening. The second portion and the fourth portion define a second opening larger than the first opening. The first edge has a length less than or equal 0.785 inches. The second edge also has a length less than or equal 0.785 inches. 
         [0012]    A first fillet extends between the first angled surface and a second fillet extends between the second angled surface and the fourth portion. The first fillet and the first angled surface define a first point of intersection. The first point of intersection is about 1.05 inches from an opposite end of the first portion. In addition, the second fillet and second angled surface define a second point of intersection. The second point of intersection is about 1.05 inches from an opposite end of the second portion. 
         [0013]    In one embodiment, a magazine for a firearm comprises a pair of sidewalls coupled together to define an enclosed cavity sized to receive ammunition cartridges. A pair of opposing projections extends from an end of the pair of sidewalls. Each of the opposing projections curves about 90 degrees toward the center of the magazine. Each of the pair of opposing projections has an edge extending about 0.785 inches from a second of the pair of sidewalls. Each pair of opposing projections has an angled surface extending from the edge and away from the center of the magazine. Each of the angled surfaces has a third end about 1.05 inches from the second end. 
         [0014]    The pair of sidewalls defines an opening having a first portion between the edges and a second portion between the third end and a fourth end opposite the first end. The angled surfaces define a transition opening between the first portion and the second portion. The enclosed area is sized to receive 30 ammunition cartridges in one embodiment and to receive 20 ammunition cartridges in another embodiment. 
         [0015]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0017]      FIG. 1  is top plan view of a magazine with portions shown in phantom for an alternative embodiment; 
           [0018]      FIG. 2  is a partial front view of the magazine of  FIG. 1  with portions shown in phantom for an alternative embodiment; 
           [0019]      FIG. 3  is a partial perspective view of the magazine of  FIG. 1 ; 
           [0020]      FIG. 4  is a side view, portions in phantom, of the magazine of  FIG. 1  with cartridges inserted into the magazine; 
           [0021]      FIG. 5  is a top view of the loaded magazine of  FIG. 4 ; 
           [0022]      FIG. 6  is a top view of another embodiment of a loaded magazine; and 
           [0023]      FIG. 7  is a top view of yet another embodiment of a loaded magazine. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIGS. 1-5  illustrate an exemplary embodiment of the magazine  20  for a firearm (not shown). While the magazine  20  may be described herein with respect to a rifle, such as an M-16 or an AR-15 type of rifle for example, the claimed invention should not be so limited and the magazine  20  may be used with any of numerous types of firearms. Magazines  20  of this type are generally interchangeable within a particular model firearm such that the user may fill several magazines with ammunition cartridges  22  ( FIG. 4 ). During use, the cartridges  22  are moved by a follower  24  and sequentially exit through a top opening  26  in a magazine box  28 , at which point the cartridge  20  moves into the receiver section of the firearm (not shown). When the magazine  20  is depleted, the follower  24  is disposed adjacent the opening  26 . The user may desire to exchange the depleted magazine  20  for a full magazine. It should be appreciated that the magazine  20  is intended to hold a predetermined number of cartridges  22 , such as 10, 20 or 30 cartridges, for example. 
         [0025]    The magazine  20  has a magazine box  28  that is configured to be received by the firearm. The magazine box  28  may be straight along its length or have a curvature. The magazine box  28  includes the opening  26  and is generally formed from a metal material, such as aluminum or steel, or a molded plastic for example. The magazine box  28  may be made from sheet metal that forms walls  30  which define a generally hollow interior portion  31 . The magazine box  28  may include a number of features, such as recesses  32  for example, that allow the magazine box  26  to guide the cartridges into a proper position within the magazine box  26 . In one embodiment, the wall of the recesses may be flattened at one side within the interior portion. 
         [0026]    On one end  34  of the magazine box  23 , the walls  30  turn inward towards the center of the magazine to form a pair of lip-like tabs or projections  36 . In the exemplary embodiment, the projections  36  have a curved portion  41  which extends 90 degrees relative to the walls  30 . The projections extend from one end  38  of the magazine box  28  and extend laterally along the wall  30  toward the center of the magazine box  23 . In the exemplary embodiment, the end  38  of the projections  36  is planar or co-linear with the end  40  of the magazine box. In another embodiment, the end  38  may be offset from the end  40  towards the center of the magazine box  28 . 
         [0027]    Adjacent the projections  36 , walls  30  may also turn inward to form a second pair of projections  37 . The second pair of projections  37  is spaced apart laterally by a distance x ( FIG. 2 ) from the end of the projections  36  to form a step on the end of the magazine box  28 . In the exemplary embodiment, the end  40  may have an extending raised portion  42 . 
         [0028]    The projections  36  have a second end  44  opposite the end  40  that is centrally disposed relative to the opening  26 . In the exemplary embodiment, the second end  44  includes an angled surface  46  that transitions an inner edge  48  from a narrow portion  50  to a wider portion  52  such that the space between the projections  36  enlarges as the projections extend toward the central portion of the magazine box  28 . The angled surface  46  has a first end  56  at distance  58  from the end  38  and a second end  60  at a distance  62  from the end  38 . 
         [0029]    In the exemplary embodiment for magazine  20 , the distance d is approximately 0.785 inches (19.939 millimeters) and the distance D is approximately 1.05 inches (26.695 millimeters). In one embodiment, the end  60  includes a curved surface or fillet  47  that transitions between the angled surface  46  and the wider portion  52 . The foregoing dimensions for some embodiments can vary ±0.125 inches and still provide the beneficial characteristics of reducing misfeeding or jamming a cartridge during operation. 
         [0030]    It should be appreciated that the surface  46  appears to be a straight linear surface when viewed from the top of the magazine. However, since the projections includes a curved surface  41  that bends the projections 90 degrees towards the centerline of the magazine, the surface  46  may also include some curvature. Further, the ends  56 ,  60  may have a radius, or may be a sharp edge. 
         [0031]    With reference to  FIGS. 6 and 7 , other magazine/projection configurations are also possible. Magazine  20 A is configured for  20  cartridges. The magazine projections  36 A do not extend to the end  38 A of the magazine so that the back rim of the bullet is exposed as viewed from the top. Magazine  20 B is configured for 30 cartridges. The respective projections  36 A,  36 B extend to the end  38 B of the magazine. 
         [0032]    For magazines  20 A and  20 B, the apex at the forward end of the points  56 A and  56 B is approximately 0.228 further toward the front of the bullet than that of magazine  20  in  FIG. 1 . The angle of surfaces  46 A and  46 B is approximately 72 degrees as opposed to the 25 degree angle of surface  47  for magazine  20 . The angle of fillet  47 A,  47 B as viewed in  FIG. 2  is approximately 45 degrees for magazines  20 A and  20 B as opposed to the corresponding angle of approximately 23 degrees for magazine  20 , as viewed in  FIG. 2 . 
         [0033]    The angled surfaces  46 ,  46 A and  46 B have been found to be advantageous in reducing the potential for misfeeding or jamming of the cartridge during operation such that a substantially greater number of magazines may be sequentially fired from the firearm without having to lubricate or clean the magazine. Prior magazine designs had a projection that extended uniformly from end to end (e.g., no angled surface). Magazines  20 ,  20 A and  20 B which incorporate the projections  36 ,  36 A and  36 B and other features as previously described require less force to eject bullets from the magazine and into the barrel chamber. 
         [0034]    United States Governmental standards permit lubrication of the firearm after every fourth magazine that is discharged (approximately 120 rounds). Embodiments of magazine  20  have been tested by firing 200 magazines sequentially without any occurrence of jamming or misfeeding in full auto 30 round burst M-16 firearms with no lubrication during the testing. 
         [0035]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.