Abstract:
A shotgun shell magazine to be received within a mil-spec magazine of an M16/AR-15 mil-spec firearm is disclosed. The magazine comprises a magazine body having an open top end defining a cavity configured to receive one or more shotgun shells. The magazine body includes a feed lip which partially occludes the open top end and has a length between 10% and 25% of the length of the open top end. A follower having a ramped upper surface resides within the cavity. The follower is biased to direct the shotgun shells toward the open top end until the primer end of a top most shotgun shell engages the feed lip. The top most shotgun shell is angled with respect to the open top end and at least a portion of the closed end of the top most shotgun shell lies above a plane created by the open top end.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a shotgun shell magazine, and more particularly, to a shotgun shell magazine configured to be used with an automatic or semi-automatic assault-type firearm. Specifically, the present invention relates to a shotgun shell magazine configured for use with an M-16/AR-15 firearm. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are a number of automatic and semi-automatic firearms used by military personnel as well as civilians. While fully automatic firearms are generally illegal for use by the civilian population, many of the components which constitute an automatic firearm are the same as those found with legal semi-automatic models. Arguably the most popular semi-automatic assault-type firearm used by civilians, particularly within the United States, is the AR-15. The AR-15 is the semi-automatic variant of the fully automatic M16 firearm used by United States military personnel. (AR-15 is a registered trademark of Colt Industries. A number of additional manufacturers manufacture clones of the AR-15 and market these clones under separate trademarks. While used throughout the specification, it is to be understood that the term AR-15 is meant to include not only those firearms manufactured by Colt Industries, but also those additional clones and any variants thereof). 
         [0003]    The AR-15 and M16 are designed as modular firearms generally comprising a buttstock, lower receiver, upper receiver and barrel assembly. Each component is separable from one another and affords firearm owners the opportunity to customize the firearm with after-market components such as barrels of differing lengths, upper receivers designed to handle different calibers of ammunition, flashlights, hand guards, grenade or flare launchers, flash or sound suppressors, grips, and front or rear sights. To operate, the lower receiver is configured to include a trigger wherein activation of the trigger causes a cartridge housed within the chamber of the upper receiver to be fired out the barrel of the firearm by action of a reciprocating bolt carrier group. Internal mechanisms of the upper receiver expel the shell casing of the fired cartridge from the chamber while components engaged with the magazine housed within the magazine well of the lower receiver feed a new cartridge into the now-empty chamber. The buttstock mounts to the lower receiver and includes a buffer assembly and action (or recoil) spring in communication with the bolt carrier group where the spring pushes the bolt carrier group back toward the chamber in preparation of firing another cartridge. 
         [0004]    To date, most automatic and semi-automatic firearms, like the AR-15, have been configured to fire rifle cartridges. Attempts to modify these firearms, and particularly the AR-15, to fire shotgun shells have run into a number of problems. For instance, AR-15 have been modified to accommodate .410 bore shells but these modifications require lower receivers which no longer satisfy military specifications. Other modifications continue to result in jamming or binding of the shotgun shells when a shell has been fired, is being ejected, or is being extracted from the magazine and loaded within the chamber. 
         [0005]    As such, there is a need for a shotgun shell magazine which is configured to mount within a lower receiver, such as that of an M-16 or AR-15, having a magazine well meeting military specifications. The present invention addresses these and other needs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In general, an embodiment the present invention is directed to a shotgun shell magazine for use in a firearm. The magazine is detachably received within a magazine well on the firearm with the firearm configured to strip a shotgun shell from the magazine and load the shotgun shell into a firearm chamber. The magazine comprises a magazine body having an open top end and defines a cavity configured to receive one or more shotgun shells. The magazine body includes a feed lip configured to partially occlude the open top end. The feed lip may have a length between about 10% and about 25% of the total length of the open top end. A follower resides within the cavity and is biased to direct the one or more shotgun shells toward the open top end until a top most shotgun shell engages the feed lip. 
         [0007]    In a further aspect of the present invention, the feed lip has a length of about 20% of the total length of the open top end. The follower may also be biased by a magazine spring where a first end of the magazine spring engages the follower and a second end of the magazine spring engages a floor plate secured to a bottom edge of the magazine body. The follower may also include a magazine stop configured to engage a bolt catch on the firearm after the last of the one or more shotgun shells has been loaded into the firearm chamber. 
         [0008]    In still a further aspect of the present invention, each shotgun shell may have a primer end and an opposing closed end. The follower may also include a ramped upper surface whereby the follower is biased to direct the one or more shotgun shells toward the open top end until the primer end a top most shotgun shell engages the feed lip such that the top most shotgun shell is angled with respect to the open top end and at least a portion of the closed end of the top most shotgun shell lies above a plane created by the open top end of the magazine body. 
         [0009]    In yet a further aspect of the present invention, the magazine body may include a plurality of indicator holes and the follower may include an extended leg wherein the extended leg coincides with an individual indicator hole in the magazine body so as to indicate a number of shotgun shells remaining in the cavity. The extended leg may also include a colored indicator portion configured to be viewed by a user. 
         [0010]    In a further embodiment of the present invention, a shotgun shell magazine for use in a firearm may comprises a magazine body having an open top end and defining a cavity configured to receive one or more shotgun shells. Each shotgun shell may have a primer end and an opposing closed end. The magazine body may also include a feed lip configured to partially occlude the open top end. A follower having a ramped upper surface resides within the cavity and the follower is biased to direct the one or more shotgun shells toward the open top end until the primer end a top most shotgun shell engages the feed lip. In this manner, the top most shotgun shell is angled with respect to the open top end and at least a portion of the closed end of the top most shotgun shell lies above a plane created by the open top end of the magazine body. 
         [0011]    A still further embodiment of the present invention is directed to a shotgun shell magazine for use in an M16/AR-15 military specification (mil-spec) firearm. The magazine is detachably received within a mil-spec magazine well on the M16/AR-15 and the M16/AR-15 is configured to strip a shotgun shell from the magazine and load the shotgun shell into a M16/AR-15 chamber. The magazine comprises a magazine body having an open top end and defining a cavity configured to receive one or more shotgun shells. Each shotgun shell has a primer end and an opposing closed end and the magazine body includes a feed lip configured to partially occlude the open top end. The feed lip may have a length between about 10% and about 25% of the total length of the open top end. A follower having a ramped upper surface resides within the cavity and the follower is biased to direct the one or more shotgun shells toward the open top end until the primer end a top most shotgun shell engages the feed lip. In this manner, the top most shotgun shell is angled with respect to the open top end and at least a portion of the closed end of the top most shotgun shell lies above a plane created by the open top end of the magazine body. 
         [0012]    Additional objects, advantages and novel features of the present invention will be set forth in part in the description which follows, and will in part become apparent to those in the practice of the invention, when considered with the attached figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The accompanying drawings form a part of this specification and are to be read in conjunction therewith, wherein like reference numerals are employed to indicate like parts in the various views, and wherein: 
           [0014]      FIG. 1  is a side view of a representative firearm amenable for use with an embodiment of a shotgun shell magazine in accordance with the present invention; 
           [0015]      FIG. 2  is a cross sectional view of the firearm shown in  FIG. 1 ; 
           [0016]      FIG. 3  is a perspective view of an embodiment of a five shell capacity shotgun shell magazine in accordance with the present invention; 
           [0017]      FIG. 4  is a perspective view of an embodiment of a fifteen shell capacity shotgun shell magazine in accordance with the present invention; 
           [0018]      FIG. 5  is a side view of the shotgun shell magazine shown in  FIG. 4 ; 
           [0019]      FIG. 6  is a cross section view of the shotgun shell magazine shown in  FIG. 5  with fifteen shotgun shells loaded into the magazine; 
           [0020]      FIG. 7  is a cross section view of the shotgun shell magazine shown in  FIG. 6  showing the magazine empty of shotgun shells; 
           [0021]      FIG. 8  is a side with of a follower amenable for use within an embodiment of a shotgun shell magazine in accordance with the present invention; and 
           [0022]      FIG. 9  is a perspective view of the follower shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Referring to the drawings in detail, and specifically to  FIGS. 1 and 2 , a firearm, such as the AR-15, is generally indicated by reference numeral  100 . Firearm  100  may be a modular firearm consisting of a number of components and subcomponents. Major components of firearm  100  may include lower receiver assembly  110 , upper receiver assembly  112 , buttstock assembly  114  and barrel assembly  116 . To assemble a completed firearm, upper receiver assembly  112  is coupled to lower receiver assembly  110  while buttstock assembly  114  is connected to the lower receiver assembly  110  and barrel assembly  116  is mounted onto upper receiver assembly  112 . Lower receiver assembly  110  is configured to include a magazine well  118  adapted to slidably receive a magazine  120  therein. Magazine  120  may carry one more cartridges, bullets or shells  122  which may be serially loaded within a chamber  124  in upper receiver assembly  112 . Activation of the firing mechanism (not shown) is controlled by trigger  126 . A grip  128  (such as a pistol grip, as shown) allows the user to aim and control the firearm while placing the user&#39;s trigger index finger in close proximity to the trigger. In this manner, the user can aim the firearm to the target and extend the trigger index finger to engage the trigger without losing control or accuracy of the firearm. 
         [0024]    Most assault-type firearms are configured to be operated as rifles and include a rifled barrel and are chambered to receiver and fire rifle cartridges. By way of example, the most ubiquitous civilian assault weapon, the AR-15, is generally chambered for standardized rounds such as the Remington .223 cartridge or the 5.56×45mm NATO military cartridge. As a result, magazines, and more importantly the magazine well configured to receive these magazines, of the AR-15 have been standardized, with such standardization being generally referred to as meeting United States Military Standards or, more commonly as being “mil-spec”. Assault weapons, such as the AR-15, have also been modified to chamber and fire .410 bore shotgun shells. However, these firearms suffer from a number of drawbacks. For instance, 2.5 inch long shotgun shells tend to bind within the chamber and/or magazine thus leading to performance failures. In an attempt to alleviate these binding issues, firearms have been modified such that the magazine well of the lower receiver is slightly larger than the standard AR-15 magazine well such that the larger magazine well can receive a larger magazine such that the shotgun shells can more repeatably be extracted from the magazine and chambered within the upper receiver. This modification, however, renders the lower receiver assembly no longer mil-spec and also leads to difficulties when mating the upper and lower receivers. 
         [0025]    As shown in  FIGS. 2-6 , an embodiment of a shotgun shell magazine  120 / 120 ′ of the present invention is configured to reside within the magazine well  118  of a mil-spec AR-15 firearm  100 . Shotgun shell magazine  120  includes a magazine body  130  that may be proportioned so as to define a 5 round magazine (i.e. can receive a maximum of five .410 bore shotgun shells  122 ). See  FIG. 3 . However, alternative capacity magazines, such as a 15 round magazine  120 ′ (see  FIG. 4 ), may be constructed in accordance with the teachings of the present invention as will be discussed more fully below. It should be understood by those skilled in the art that magazines may be produced which include any desired capacity and that such alternative magazines are to be considered within the teachings of the present invention. 
         [0026]    With reference to  FIGS. 4-6 , magazine  120 ′ is generally comprised of a magazine body  130 ′ defining a magazine cavity  132 . Cavity  132  is proportioned to receive one or more shotgun shells  122 . In accordance with one aspect of the present invention, shotgun shells  122  are 2.5 inch long .410 bore shotgun shells filled with either shot or slugs. The portion  134  of magazine body  130 ′ may be slightly narrower than the remainder  136  of magazine body  130 ′ so as to form a step  138 . Portion  134  is proportioned to be removably insertable within magazine well  118  (see  FIG. 1 ) while step  138  abuts the lower periphery of magazine well  118  so that magazine  120 ′ is properly loaded within magazine well  118 . To that end, portion  134  may include one more grooves  140  that mate with corresponding ridges (not shown) defined on the internal faces of magazine well  118  to ensure that magazine  120 ′ is mounted within firearm  100  in the proper orientation. 
         [0027]    The top edge  142  of magazine body  130 ′ generally defines an opening to cavity  132  such that shotgun shells  122  may pass out from magazine  120 ′ and into chamber  124  of upper receiver assembly  112  (see  FIG. 1 ). To allow controlled, selective extraction of a single shotgun shell  122 , a feed lip portion  144  of top edge  142  is configured to extend around and partially encircle the metal casing  146  at the rim end  148  of the top most shotgun shell  122 . In accordance with an aspect of the present invention, a length  145  of feed lip portion  144  is proportioned to be less than about 25% of the total length  135  of portion  134  of magazine body  130 ′, in more particularly about 20% of the total length  135 . In this manner, shotgun shells  122  may be serially extracted from magazine by the bolt carrier (not shown) within the upper receiver assembly  112  without jamming or binding the shotgun shell  122  within magazine body  130 ′ or chamber  124  as is known with current attempts at providing AR-15 magazines for .410 bore shotgun shells. To that end, magazine body  130 ′ may define a recess  150  configured and positioned such that the bolt carrier can engage metal casing  146  to slide the shotgun shell  122  beyond the feed lip portions  144 . Once shotgun shell  122  clears the obstruction created by feed lip portions  144 , the shotgun shell  122  can then be directed into chamber  124  for eventual firing. To control lateral movement of the plastic hull portion  154  of shotgun shell  122 , top edge  142  may further include upwardly extending guide lips  156 . 
         [0028]    Housed within cavity  132  of magazine body  130 ′ is a follower  160  onto which are loaded one more shotgun shells  122 . Follower  160  is biased upwardly toward top edge  142  by way of a biasing member  162 . Biasing member  162  may be a magazine spring as is known in the art. The opposing end of biasing member  162  may be fastened to a floor plate  164  which in turn is secured to the bottom edge  166  of magazine body  130 ′. Floor plate  164  may be directly fastened to bottom edge  166  or may be constrained within cavity  132  by a magazine base plate  168  which is fastened or physically bonded to bottom edge  166 . Biasing member  162  exerts a spring force against follower  160  such that the top most shotgun shell  122  is constrained within magazine body  130 ′ by feed lip portions  144  as discussed above. Once a shotgun shell has been fired and the next subsequent shotgun shell extracted by the bolt carrier, follower  160  through urging of biasing member  162  advances the immediately next shotgun shell  122  until this next shell engages the feed lip portions. Shotgun shells  122  continue to load within chamber  124  upon repeated firing of the firearm  100  until such time the last shotgun shell is loaded into the chamber. 
         [0029]    Upon loading of the bottom most shotgun shell  122  within chamber  124 , a magazine stop  170  resident within a stop cavity  172  defined within follower  160  may be biased outwardly via a stop biasing member  174  housed within combined bore  176   a,    176   b  in follower  160  and stop  170 , respectively (see  FIG. 7 ). The outwardly extending magazine stop  170  may then engage the bolt catch (not shown) in the lower receiver to stop the bolt&#39;s travel thereby enabling the bolt to be locked to the rear (toward buttstock  114 ). The empty magazine can then be removed from magazine well  118  and a new, loaded magazine may then be inserted. The bolt catch may then be disengaged such that the bolt carrier may strip the top most shotgun shell from the newly loaded magazine. When magazine  120 ′ contains one or more shotgun shells  122 , biasing member  174  is compressed by magazine stop  170  engaging the internal surface of magazine body  130 ′ such that magazine stop rides along the internal surface until such time as the bottom most shotgun shell  122  is loaded within chamber  124  and magazine stop extends outwardly from recess  150  as described above. 
         [0030]    Turning now to  FIGS. 8 and 9 , an isolated view of follower  160  is shown. As shown most clearly in  FIG. 8 , follower  160  is configured include a ramped upper surface  180  extending at an angle  182  with respect to the plane  183  defined by top face  171  of magazine stop  170 . As seen in  FIG. 9 , ramped upper surface  180  may be adapted to include a concave recess  184 . Concave recess  184  may be configured to have a radius equal to or slightly larger than the external circumference of a standard .410 bore shotgun shell  122 . In this manner, shotgun shell  122  should nest within recess  184  such that rolling of shotgun shell  122  on ramped upper surface  180  is reduced, particularly once shotgun shell  122  has disengaged from feed lip portions  144  upon being loaded into chamber  124  as described above. Ramped upper surface  180  of follower  170 , coupled with feed lip portions  144 , causes at least a portion of the closed (i.e. crimped or rolled) end  154  of top most shotgun shell  122  to extend externally from magazine body  130 ′ at an angle  190  with respect to a plane  191  created by feed lip portions  144  while the metal casing  146  engages feed lip portions  144  (see  FIG. 5 ). As described above, upwardly extending guide lips  156  of magazine housing  130 ′ aid in preventing lateral movement of the top most shotgun shell  122 . Angling of the top most shotgun shell  122  in such a manner facilitates proper stripping and chambering of the shotgun shell by the bolt carrier during reloading of firearm  100 . 
         [0031]    In accordance with a further aspect of the present invention, follower  160  may include one or more downwardly extending legs  192   a,    192   b.  These downwardly extending legs may facilitate placement and compressive loading of magazine biasing member  162 . Magazine body  130 ′ may include a plurality of indicator holes  194  (see  FIGS. 4 and 7 ) which are spaced apart from one another such that as follower  160  is biased upwards through subsequent loading of successive shotgun shells as described above, an indicator portion  196  on follower  160  is viewable through the respective indicator hole which corresponds to the number of shotgun shells  122  remaining within magazine  120 ′. In this manner, the firearm user may monitor the number of shells remaining by visually determining where the indicator portion  196  is located along magazine body  130 ′. If follower  160  is fabricated of materials identical to or similar to magazine body  130 ′ such that visually interrogation of the magazine body  130 ′/follower  160  does not readily indicate the number of shells remaining, identifier portion  196  on one or both of legs  192   a,    192   b  (such as leg  192   b  as shown in  FIGS. 8 and 9 ) may be colored so as to be more readily viewable by the firearm user through indicator holes  194 . 
         [0032]    Although the present invention has been described in considerable detail with reference to certain aspects thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the aspects contained herein. 
         [0033]    All features disclosed in the specification, including the claims, abstract, and drawings, and all the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.