Double stack box magazine for rimmed cartridges of varying length

Abstract

A multi-column box magazine for rimmed ammunition cartridges of varied lengths has an elongated housing with a neck portion where cartridges are arranged in a single column and a mouth at an upper feed end through which cartridges are inserted and extracted. In a multi-column portion, cartridges are arranged in laterally alternating columns, and in a transition portion the alternating columns are transitioned into the single column as the cartridges are moved toward the mouth within the housing. A follower is biased by a spring toward the mouth. The multi-column portion has a forward interior surface limiting forward movement position of cartridges, which varies depending on individual cartridge length, and the neck portion having a forwardly sloped rearward wall which confronts the cartridge rim and shifts the cartridge forward, as needed, as cartridges are moved upwardly within the housing to the mouth.

Claims

1. A multi-column box magazine for rimmed ammunition cartridges of varied lengths, comprising: an elongated housing having a neck portion in which cartridges are arranged in a single column and having a mouth at an upper feed end through which cartridges are inserted and extracted, an elongated multi-column portion in which cartridges are arranged in laterally alternating columns, and a transition portion between the neck portion and the multi-column portion in which the two alternating columns are transitioned into the single column as the cartridges are moved toward the mouth within the housing; a follower configured to move in the housing; a spring configured to bias the follower toward the mouth; and the multi-column and transition portions having a forward interior surface limiting forward movement position of cartridges, the position of the cartridge rim varying depending on individual cartridge length, and the neck portion having a forwardly sloped transition edge surface on the interior rearward wall which confronts the cartridge rim and shifts the cartridges forward, to a position with the rim forward of its forwardmost position in the multi-column and transition portions as the cartridges are moved upwardly within the neck portion to the mouth.

2. The magazine of claim 1, further comprising a clearance channel in at least one of opposed interior lateral surfaces of the housing, the channel having: a first channel portion in which a width of the channel allows clearance for cartridge rims without respect to forward and rearward position of the cartridges within the housing, the forward movement position varying depending on individual cartridge length, a second channel portion in the neck portion of the housing in which a forward wall of the channel slopes forwardly to allow the cartridge rim to shift to a forward position within the housing as the cartridges are moved toward the mouth, and a third channel portion providing transition between the first and second channel portions and having a forwardly sloped rearward wall which confronts the cartridge rim and shifts the cartridges forward as the cartridges are moved upwardly within the housing in the neck portion.

3. The magazine of claim 1, wherein the housing is detachable from a firearm.

4. The magazine of claim 1, wherein the housing is forwardly curved.

5. The magazine of claim 1, wherein the follower moves along elongated guides configured at forward and rearward interior walls of the housing and extend substantially the full length of the multi-column portion.

6. The magazine of claim 5, wherein the follower is configured to move along the guides to a position substantially completely within the neck portion of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Like reference numerals are used to indicate like parts throughout the various drawing figures, wherein:

(2) FIG. 1 is a pictorial view of a double-stack detachable box magazine for shotgun cartridges according to an embodiment of the present invention;

(3) FIG. 2 is a pictorial view of the magazine shown in FIG. 1 from an alternate angle;

(4) FIG. 3 is a pictorial exploded view thereof;

(5) FIG. 4 is a longitudinal sectional view to the rear taken substantially along line 4-4 of FIG. 2 with the spring removed for clarity;

(6) FIG. 5A is a lateral medial sectional view of the magazine, without a spring, showing cartridges in phantom line, and showing the follower in a lowered position;

(7) FIG. 5B is a similar view showing the follower in the topmost position;

(8) FIG. 6 is a lateral medial enlarged fragmentary sectional view of an upper part of the magazine with the position of rimmed cartridges shown in phantom;

(9) FIGS. 7A, 7B, and 7C are a cross-sectional views taken substantially along the corresponding lines indicated in FIG. 5A; and

(10) FIGS. 8A and 8B are isometric views of the follower.

DETAILED DESCRIPTION

(11) With reference to the drawing figures, this section describes particular embodiments and their detailed construction and operation. Throughout the specification, reference to one embodiment, an embodiment, or some embodiments means that a particular described feature, structure, or characteristic may be included in at least one embodiment. Thus, appearances of the phrases in one embodiment, in an embodiment, or in some embodiments in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the described features, structures, and characteristics may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like. In some instances, well-known structures, materials, or operations are not shown or not described in detail to avoid obscuring aspects of the embodiments. Forward will indicate the direction of the muzzle and the direction in which projectiles are fired, while rearward will indicate the opposite direction. Lateral or transverse indicates a side-to-side direction generally perpendicular to the axis of the barrel. Although firearms may be used in any orientation, left and right will generally indicate the sides according to the user's orientation, top or up will be the upward direction when the firearm is gripped in the ordinary manner.

(12) Referring to the various drawing figures, and first to FIGS. 1 and 2, therein is shown at 10 a magazine according to a preferred embodiment of the present invention. Referring now also to FIG. 3, which is an exploded view of the various parts of the magazine 10, it includes a magazine body 12, an attached metallic member 14, which provides feed lips 16 and snaps in place at an upper end of the magazine body 12. Also shown is a follower 18, a coil compression spring 20, a floor plate guide 22, and a floor plate 24. As is standard with any box magazine, it is assembled by inserting the follower 18 through an opening 26 at a bottom end 28 of the magazine body 12.

(13) The coil spring 20 is inserted through the bottom opening 26 behind or along with the follower 18. The spring 20 may have a rectangular shape (as shown), may be a cylindrical or oval coil (not shown), or a combination of both, and its width or diameter may be tapered in cross-section along its length. In the present invention, it has been found useful to have a floor plate guide 22 with a recess, protrusions 30 or other means for holding the spring 20 in a properly centered position at the lower end. The floor plate guide 22 is inserted into the bottom opening 26 behind or along with the spring 20 and then the floor plate 24 is slid into a closed position by engaging the lateral grooves 32 on lateral rails 34, which are adjacent the bottom opening 26 of the magazine body 12.

(14) For purposes of illustration only, the magazine 10 shown and described herein is adapted to fit one type of 12-gauge, pump-action shotgun. It is readily adaptable to other brands or to semi-automatic configurations that use detachable magazines. Likewise, the body 12 can be extended or shortened to accommodate almost any desired number of rounds and could be modified to accommodate more than two columns of cartridges. Accordingly, the upper end 36 of the magazine body 12 is configured to properly engage a detachable coupling with a magazine opening or well in such a shotgun (not shown). The illustrated embodiment includes an attached metallic member 14 that snaps in place adjacent the upper end 36 of the magazine body 12 to provide durable feed lips 16 in accordance with some existing designs found in a single-stack, smaller capacity box magazine for such a shotgun. Alternatively, feed lips may be provided integrally with the magazine body 12 either from the same material or by encapsulating/over-molding a metallic member and the attachment interface may be adapted to any shotgun platform that accepts detachable magazines.

(15) Referring now to FIG. 4, which shows a vertical sectional view of the magazine 10 (with the spring 20 removed), it can be seen that the magazine body 12 has three distinct regions: an upper or neck portion 38; a transition portion 40; and a widened double-stack portion 42. The upper or neck portion 38 at the upper end 36 of the magazine body 12 is dimensioned as a single-stack magazine to fit within the magazine opening or well of the shotgun. The standard magazine opening or well of currently-available shotguns cannot accept the added width of a double-stack magazine body. In the prior art, the need for this narrowed neck portion had presented a challenge in that the same follower must move a double row of cartridges along the wider double-stack portion and then completely push all cartridges through a transition to a narrow neck and fully into a delivery position. In the past, this problem has been addressed by either using a follower of exaggerated length, which consumes a greater portion of the magazine's length, or using hinged follower arms that displace into a more narrow profile as they enter the neck portion of the magazine, creating a complex and expensive-to-construct design. My prior invention addressed this issue differently, as will be more fully explained below, and many aspects of that design are used in the present invention, with novel modification to accommodate the rearward offset of the column.

(16) As discussed in the background section above, reliably feeding shotgun shells in a box magazine presents challenges not found in handling rifle and pistol cartridges. Generally, a shotgun is expected to be able to handle and fire shells of the specified chamber length or shorter. Moreover, shells of any standard nominal length may vary considerably in actual length. Prior art box magazines rely on the length of each cartridge being substantially identical, within a very small acceptable tolerance and/or use of a significantly angled follower. Also, as described above, prior single-stack box magazines for shotgun shells address this challenge by engaging the rim of each cartridge on both sides within a narrow track or groove that maintained rims of subsequent cartridges in an ordered position and use a significantly angled follower to prevent binding caused by frontward/rearward shift to provide reliable feeding into a position to be stripped away by the shotgun's reciprocating bolt.

(17) Referring now to FIGS. 5A, 5B, and 6, therein are shown sectional views taken laterally substantially along the longitudinal center of the magazine 10. Cartridges 44 are shown in phantom line for clarity. In FIGS. 5A and 5B, no spring 20 is shown. The follower 18 is in a lowered position in FIG. 5A and in a topmost position in FIG. 5B. In FIG. 6, the magazine 10 is partially loaded with shotgun shells 44 of varied length, which are shown in phantom in this view. These views show the lateral interior surface 46 of the magazine body 12. The opposed lateral surface (not shown in this view) may be configured identically in a mirror image. Alternatively, the position of certain components can be vertically offset in one side relative to the other in order the balance the handling of the staggered double columns of shells 44.

(18) Adjacent the rear edge of the magazine body 12 is a relatively wide rim clearance channel 48. A rear edge 50 of the channel 48 is defined along the rearward interior surface of the magazine body 12. A forward edge 52 of the channel 48 is defined on the lateral interior surface 46. In preferred form, however, the forward edge 52 is positioned to accommodate even the shortest nominal or actual length shotgun shells 44 without confronting the rim. The cartridges 44 are allowed to shift forward (as they are inclined to do in response to the recoil forces of firing the weapon) until their forward end contacts the forward interior surface 60 of the magazine body 12.

(19) FIGS. 7A, 7B, and 7C show cross-sectional views taken substantially along corresponding lines of FIG. 5 and illustrate the relative lateral depth of the rim clearance channel 48 and lateral interior surfaces 46.

(20) The overall front-to-rear interior dimension 58 (FIG. 7C) should be configured to accept the longest expected overall length of a shotgun cartridge 44 to be used in the magazine 10 and its associated shotgun (not shown). The front-to-rear dimension 56 of the rim guide channel 48 (FIG. 7A) optimally may be selected such that the rim of a shotgun shell of the shortest expected overall length will remain between rear and forward edges 50, 52 of the clearance channel 48 when a shell is shifted forward to the point of being against or near the forward interior surface 60 of the magazine body 12.

(21) It can be appreciated by comparison of the views in FIGS. 4 and 7A-7C that while in the multi-column portion 42 of the magazine body 12, the alternating rows of shotgun shells 44 have their respective rims engaged in only one of the laterally opposed rim guide channels 48. Because only a very minor portion of the cartridge rim could be engaged in the clearance channel 48 in the double-stacked portion 42 of the magazine 10, it has been found that the rearward shock forces to which an attached magazine 10 is subjected when the shotgun is fired (or even when dropped or otherwise impacted) is likely to jar the cartridges 44 out of a narrow guide channel until the cartridge comes to rest against the forward interior surface of the magazine. Thus, the present design allows this inevitable movement to occur, while maintaining containment of a rim portion of each cartridge 44 in one of the rim clearance channels 48, which are relatively wide in the double-stack portion 42. The space forward of the forward edge 52 to the forward interior surface 60 is such that the rim of the shortest expected round will remain in the channel 48 when the mouth end of a cartridge 44 contacts the forward interior surface 60.

(22) Referring now also to FIGS. 8A-8D, the follower 18 has forward and rearward guide rails 62, 64, which engage forward and rearward follower guide channels 66, 68 on interior front and rear surfaces 60, 50 of the magazine body 12. The follower guide rails 62, 64 have sufficient vertical length to prevent lateral tipping of the follower 18 as it travels along the length of the magazine body 12. The forward follower guide rail 62 can be longer in vertical dimension than the rear follower guide rail 64 in the illustrated design to accommodate the curvature of the magazine body 12, as can be appreciated by a comparison of FIGS. 5A and 5B. The follower 18 may also include lateral guide rails 65 (shown in FIGS. 8A and 8B) that guide the follower 18 as it approaches its upper limit of travel and prevent forward/rearward tipping by contact with an interior edge 90 when the topmost position is reached (FIG. 5B).

(23) As best illustrated in FIGS. 4 and 8A-8D, the upper surface 70 of the follower 18 may be, for example, divided laterally into a raised convex or flat portion 72 and a lower concave portion 74. The lower concave portion 74 cradles and guides a cartridge 44 against a lateral interior surface 46 of the magazine body 12. In combination, the upper convex portion72 of the follower 18 and an adjacent cartridge 44 guides another cartridge 44 against the opposing lateral interior surface 46, maintaining portions of each cartridge rim in engagement with one of the rim guide channels 48 on each respective side. The height difference between the raised flat or convex portion 72 and lower concave portion 74 maintains sequential cartridges 44 in a vertically staggered relationship, as well as their laterally staggered relationship. Other shapes for the upper surface of the follower 18 may be selected, as desired, in order to balance the resistance of both columns of cartridges 44.

(24) As cartridges 44 are fed from the upper end 36 of the magazine 10, cartridges 44 situated lower in the magazine 10 are moved from the double-stacked portion 42 into the transition portion 40, where their relative vertical position increases as their relative lateral position decreases. This is best illustrated in FIG. 4.

(25) As cartridges 44 continue to be moved upwardly, through the transition portion 40, they enter the upper or neck portion 38 of the magazine 10, in which the cartridges 44 become vertically aligned in a single column with opposing edges of their rims both engaged in both opposing rim clearance channels 48. In a preferred form, the vertical length of the neck portion 38 is kept to the minimum length necessary to engage the magazine opening or well (not shown) of the selected shotgun, so that the combined transition portion 40 and double-stacked portion 42 of the magazine 10 may be maximized, thereby maximizing the capacity of the magazine 10.

(26) Referring again in particular to FIG. 6, therein is shown an enlarged view of an upper portion of the magazine 10 seen in FIG. 5A. The shotgun cartridges 44 are shown in phantom line in order to better view internal details of the magazine body 12 and are labeled individually as 44a through 44d for clarity of discussion. Before the cartridges 44 reach the transition portion 40, excessive forward movement of the cartridges is limited by the forward interior surface 60 of the magazine body 12. This presents shorter cartridges to be presented in an appropriate forward/aft position as they reach the neck portion 38. At or near the bottom of the neck portion 38 of the magazine body 12, the back edge 50 of the rim clearance channels 48 angle toward the front edge 52, narrowing the front-to-rear width of the channel 48. The rear edge 50 of the channel 48 (which is the rear wall of the magazine body 12) presents an angled transition edge 76 which progressively decreases the width of the channel 48 toward a relatively narrowed rim guide channel 78. When cartridges 44a, 44b are in the neck portion 38, they are no longer limited in forward movement. Longer cartridges may be pushed forward by the rear edge surface 76, to the extent necessary, so they will be in an appropriate forward/aft position as they reach the feed lips 16 at the mouth of the magazine body 12.

(27) As cartridges 44 are stripped from the upper end 36 of the magazine 10, cartridges at a lower position, such as that shown as 44c, migrate upwardly. Longer cartridges are pushed forward by the angled transition edge 76 to a position generally represented by cartridge 44b. At this point, even if the rims 80 of the cartridges 44 are misaligned, each cartridge 44 is moved forward until the rim 80 is positioned forward of the rim of the cartridge below it. This movement reorients the uppermost cartridge 44a relative to the cartridge 44b below it, and forces the rim 80 into appropriate alignment. In this position, the rim 80 of the cartridge 44a is pressed against the feed lips 16 by spring pressure and is in position to be stripped away and chambered by the bolt of the firearm. This configuration allows the transition portion 40 and double-stack body portion 42 of the body 12 to be situated to the rear of the mouth at the upper end 36, which was not possible in my prior design.

(28) While one or more embodiments of the present invention have been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. Therefore, the foregoing is intended only to be illustrative of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable modifications and equivalents may be included and considered to fall within the scope of the invention, defined by the following claim or claims.