Abstract:
The present disclosure provides ammunition magazine casing and follower systems. The magazine casing may comprise a pair of spines running along a length of an interior rear wall of the magazine casing, the spines being raised in relation to other portions of the interior rear wall and stopping at a point in the magazine casing where an exterior geometry of the magazine casing changes from substantially curved to substantially straight.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/979,284 filed Dec. 22, 2015 and entitled “Ammunition Magazine,” which is a continuation of U.S. patent application Ser. No. 13/744,224, now U.S. Pat. No. 9,347,720, filed Jan. 17, 2013 and entitled “Ammunition Magazine,” which claims priority to U.S. Provisional Application No. 61/587,604 filed Jan. 17, 2012 and entitled “Ammunition Magazine,” the entire disclosures of which are hereby incorporated by reference for all proper purposes, as if fully set forth herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to firearms and more particularly, relates to an improved ammunition magazine. 
       BACKGROUND OF THE INVENTION 
       [0003]    Ammunition magazines are well known in the art of firearms. Their basic construction is a containment shell with two open ends. One end is deemed the “floor” of the magazine and is covered by a plate while the opposite end is the “feed” end and interfaces with the weapon. Inside the volume defined by the shell and plate is a spring and follower assembly. When ammunition is loaded into the magazine, the ammunition pushes the follower down towards the floor and thereby compresses the spring. In use, when one cartridge of ammunition is expended, the compressed spring releases and pushes the follower and associated ammunition upwards toward the feed end and the next round of ammunition is thereby readied. 
         [0004]    Prior magazines have been manufactured in many different configurations and of different materials. Perhaps the best known in the U.S. are the AK-47 and the USGI AR15/M16 magazines. These magazines function similarly, though they are made with slight variations to interface with their host system. Of notable difference is that the AK-47 magazine has a relatively constant curvature while the AR15/M16 magazine has a less curved lower region that gradually resolves to a more linear function towards the feed end. Both use the same type of internal system. Of particular note with both systems, and all follower magazine systems, is that the system works well only as the follower smoothly and levelly travels the inside of the magazine. As the follower must move, there is room for the follower in all the known prior art magazines to move axially, or “wobble,” and possibly jam. This is notorious in the AR15/M16 magazine style as the geometry of the magazine is inherently not uniform. Previous attempts to address the many issues with the AR15/M16 magazine have been made, including magazines previously invented by the applicants and disclosed in U.S. Pat. Nos. 7,908,780, issued Mar. 22, 2011, and 8,069,601, issued Dec. 6, 2011. Both of these patents and products based upon them have fared well in the market as solutions to AR15/M16 magazine issues and serve as a basis for the magazine construction disclosed herein. Accordingly, these two patents are incorporated by reference in their entirety herein. 
         [0005]    Of particular interest in the construction of ammunition magazines is the shape of and interface between the follower and the floorplate. The interface needs to be stable when the magazine is fully loaded and, traditionally, the floorplate has been flat with the follower having some contact with the floor plate when the magazine was fully loaded. Various follower designs have been introduced in efforts to improve the performance of ammunition magazines; however, there is usually some trade-off between the motion of the follower and associated round stack and ultimate stability. 
         [0006]    The present invention is a polymer magazine utilizing an improved floor plate and interfacing follower. The follower is constructed with fore and aft legs, the fore leg being longer. The floor plate is generally a two-piece floor plate and lock plate combination, the lock plate becoming a shoe for the follower when the magazine is fully loaded. In an alternate, slim-line version, the lock plate is omitted and the floor plate serves as the follower&#39;s shoe. 
       SUMMARY OF THE INVENTION 
       [0007]    An aspect of the present disclosure provides an ammunition magazine casing which may comprise a pair of spines running along a length of an interior rear wall of the magazine casing, the spines being raised in relation to other portions of the interior rear wall and stopping at a point in the magazine casing where an exterior geometry of the magazine casing changes from substantially curved to substantially straight. 
         [0008]    Another aspect of the disclosure provides an ammunition magazine casing which may comprise a pair of spines running lengthwise along an interior rear wall of the casing, the spines protruding from at least a portion of the interior rear wall and stopping at a point on the interior wall adjacent to an over-insertion stop on an exterior of the casing. 
         [0009]    Yet another aspect of the disclosure provides an ammunition magazine casing and follower system which may comprise a parallel set of spines located on an interior length of the casing, the set of spines defining channels on either side of each spine. The follower may be configured to interface with the spines while traveling along at least some of the length of the casing such a space created by the channels between an end portion of the follower and a wall of the casing is larger than any space between both the end portion of the follower and the spines and the end portion of the follower and the wall of the casing that is not part of the channels 
         [0010]    Many objects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views. 
         [0011]    Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0012]    As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a magazine utilizing an embodiment of the invention. 
           [0014]      FIG. 2  bottom plan view of the magazine of  FIG. 1 . 
           [0015]      FIG. 3  is a top plan view of the magazine of  FIG. 1 , with its spring compressed. 
           [0016]      FIG. 4  is sectional view of the magazine of  FIG. 3 , taken along line A-A. 
           [0017]      FIG. 5  is a close up view of the magazine of  FIG. 4 , taken in circle B. 
           [0018]      FIG. 6  is a perspective view of the follower, lock plate and spring of the magazine of  FIG. 1 . 
           [0019]      FIG. 7  is a side elevation of the follower, spring and lock plate of  FIG. 6 . 
           [0020]      FIG. 8  is a rear elevation of the follower, spring and lock plate of  FIG. 6 . 
           [0021]      FIG. 9  is a perspective view of a magazine using an alternate embodiment of the invention 
           [0022]      FIG. 10  is front elevation of the magazine of  FIG. 9 . 
           [0023]      FIG. 11  is a rear elevation of the magazine of  FIG. 9 . 
           [0024]      FIG. 12  is a top plan view of the magazine of  FIG. 9 , with its spring compressed. 
           [0025]      FIG. 13  is sectional view of the magazine of  FIG. 12 , taken along line C-C. 
           [0026]      FIG. 14  is a close up view of the magazine of  FIG. 13 , taken in circle D. 
           [0027]      FIG. 15  is a perspective view of the follower, lock plate and spring of the magazine of  FIG. 9 . 
           [0028]      FIG. 16  is a side elevation of the follower, spring and lock plate of  FIG. 15 . 
           [0029]      FIG. 17  is a rear elevation of the follower, spring and lock plate of  FIG. 15 . 
           [0030]      FIG. 18  is a partial lower perspective view of an alternate magazine casing. 
           [0031]      FIG. 19  is another partial lower perspective view of the magazine casing of  FIG. 18 . 
           [0032]      FIG. 20  is a sectional view of the casing of  FIG. 19 . 
       
    
    
     REFERENCE NUMBERS USED IN THE SPECIFICATION 
       [0000]    
       
           1 —Magazine 
           2 —Magazine Casing 
           3 —Follower Spring 
           4 —Magazine Spine 
           5 —Paint Matrix 
           6 —Front Magazine Notch 
           7 —Magazine Stop 
           8 —Rear Magazine Notch 
           9 —Spine Groove 
           10 —Floor Plate 
           12 —Lock Plate 
           14 —Lock Plate Tab 
           16 —Lock Plate Cradle 
           18 —Lock Plate Pillar 
           20 —Magazine Follower 
           22 —Follower Front Leg 
           24 —Follower Rear Leg 
           30 —Alternate Floor Plate 
           32 —Alternate Cradle 
           34 —Alternate Pillar 
           36 —Cradle Tooth 
           38 —Pillar Tooth 
       
     
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0055]    With reference now to the drawings, the preferred embodiment of the ammunition magazine is herein described. It should be noted that the articles “a”, “an” and “the”, as used in this specification, include plural referents unless the content clearly dictates otherwise. 
         [0056]    With reference to  FIG. 1 , the magazine  1  generally comprises a generally rectangular casing, having short fore and aft sides and longer lateral sides and an open floor end and an open feed end. Feed lips are provided at the feed end to interface with a weapon and to guide cartridges into the firing chamber of said weapon. The floor end is capped with a floor plate  10 . Ideally, floor plate  10  is secured by a lock plate  12  ( FIG. 5 ). The manner in which the lock plate  12  secures the floor plate  10  is as follows: the floor plate  10  is configured to slide over a rim at the floor end of the magazine. The lock plate  12  rests against the floor plate  10  and is under pressure from the follower spring  3 . A tab  14  of the lock plate  12  is positioned to pass through an orifice of the floor plate ( FIG. 2 ). As the lock plate  12  is under pressure, the tab maintains its position and prevents the floor plate  10  from sliding off of the magazine&#39;s rim. 
         [0057]    As shown in  FIGS. 4-8 , the follower  20  may be constructed with rear leg  24  shorter than the front leg  22 . This construction makes the system clear dirt and grime easier than having the two legs equal in length. To compensate for the shortened leg  24 , a pillar  18  is constructed on the lock plate  12  in a manner to abut the shorter rear leg  24  when the spring  3  is compressed. Together, the pillar  18  and shorter rear leg  24  should be about equal to the length of the forward leg  22 . Together, these structures will prevent the spring  3  from being over-compressed and provide greater stability to the round stack and system when the spring is compressed to its maximum extent. 
         [0058]    Another improvement is the addition of a cradle  16  at the fore end of the lock plate  12 . The cradle  16  extends into the magazine body and will interface with the forward leg  22  as the spring  3  is compressed. The cradle  16  serves as a block in the instance where a large amount of force compresses the spring  3  and, in turn, pushes the lock plate  12  and floor plate  10  slightly beyond the lower rim of the magazine  1 . Without the cradle  22 , such circumstances may cause the lock plate  12  to slip out of alignment with the magazine casing. The cradle  22  also contributes to follower stability at the lower magazine extremity. Together, the pillar  24  and cradle  22  make the lock plate  12  a type of shoe for the spring  3  and follower  20 . 
         [0059]      FIG. 9  depicts a magazine utilizing an alternate embodiment of the invention where the floor plate  30  is a slim-line floor plate and performs functions of both the floor plate  10  and lock plate  12  of the previous embodiment. Modified floor plate  30  engages notches  6  and  8  on the front and back sides of the magazine  1  respectively, shown in  FIGS. 10 and 11  Like the previous embodiment, the modified floor plate  30  becomes a shoe for the spring  3  and follower  20 , as shown in  FIGS. 12-14 . Floor plate  30  provides a pillar  34  for the rear leg  24  of follower  20  and a narrower cradle  32  for the forward leg  22 . These structures function generally in the same manner as described above. Of note, both cradle  32  and pillar  34  have teeth  36 ,  38  which interface with notches  6 ,  8  in the magazine body, thus securing the floor plate  30  to the magazine  1  ( FIGS. 15-17 ). 
         [0060]    Another improvement to the structure of the magazine is illustrated in  FIGS. 18-20  where a pair of spines  4  is built into a lower hind area of the magazine. Spines  4  are in essence a continuation of a trench in the rear of the magazine that nests the rear leg  24 , as can be seen in  FIG. 5 . The spines  4  are essentially formed by removing material from the wall of the magazine around the trench, forming two channels  9  on either side of the spines  4  with the trench continuing therebetween. Ideally, the spines  4  and channels  9  may extend as far up the magazine as the point where the exterior geometry straightens so as to be inserted into a magazine well of a firearm, roughly as far as over-insertion stop  7  in  FIG. 9 . The purpose of this construction is to aid in clearance of debris and grit and to improve processing in general. As the spines  4  are, in essence, a continuation of the trench, the follower is guided by them and, if extended far enough up the magazine, the point where the channels  9  end could be used as an internal follower stop. 
         [0061]    In all of these embodiments, the preferred magazine body is comprised of a glass-reinforced thermoplastic polymer selected to resist the heat generated from firing a rifle. However, other polymers, like polycarbonate, may be used and the magazines may be made in any color or opacity (which can reduce or eliminate the need for a magazine level indicator). Some polymers, such as polycarbonate, may be used without reinforcement. Steel, carbon fiber, and other materials may also be used to reinforce the magazine. Likewise, the magazine body may be made of other materials having suitable strength and durability, such as titanium, ceramics, laminates, amorphous metals, etc. The follower is preferred to be made of polyoxymethylene, acetal resin available commercially from DuPont under the trade name DELRIN®, though other materials are suitable, just not preferred. The magazine body may also feature improvements to aid the user in other manners ( FIG. 1 ). At least one paint matrix  5  may be added to either the body or floor plate  30  of the magazine. Paint matrix  5  is a plurality of divots in the body of the magazine that, when painted over with some form of mark or indicia, will hold the paint mark within the cavities of the divots. An over-insertion stop  7  ( FIG. 9 ) may also be provided so that the magazine will abut the walls of the magazine well and so prevent over-insertion of the magazine. 
         [0062]    Although the present invention has been described with reference to preferred embodiments, numerous modifications and variations can be made and still the result will come within the scope of the invention. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.