WO2009025889A2

WO2009025889A2 - Rifle magazine

Info

Publication number: WO2009025889A2
Application number: PCT/US2008/063459
Authority: WO
Inventors: Jeffrey M. Cahill
Original assignee: Tango Down, Llc.
Priority date: 2007-05-10
Filing date: 2008-05-12
Publication date: 2009-02-26
Also published as: GB0919663D0; DE112008001241T5; GB2461234A; WO2009025889A3

Abstract

The present invention relates to rifle magazines, and more particularly to an improved detachable magazine (100) for a rifle. The improved magazine (100) has upper and lower portions (220,222) molded from a high-impact polymer. Feed lips (215) at the top of the upper portion of the magazine (100) are optionally reinforced with stainless steel or another suitable metal. The molded lower portion (222) includes an integral floor (232), instead of a separate floor piece. The upper and lower portions (220,222) can be adhered together with a high-strength adhesive. The use of a high- impact polymer reinforced with metal feed lips (214) produces an impact-resistant, light-weight, and reliable magazine (100).

Description

RIFLE MAGAZINE

FIELD OF THE INVENTION

[0001] The present invention relates to rifle magazines, and more particularly to an improved detachable magazine for a rifle.

BACKGROUND OF THE INVENTION

[0002] Many rifles utilize detachable magazines, which are devices that store and feed ammunition into the rifle. Some rifles have integrated, internal magazines that cannot be removed from the rifle, while other rifles accept detachable magazines that can be removed from the rifle, refilled with ammunition, and re-attached to the rifle. A prior art detachable magazine 100 is shown in FIG. 1. The prior art magazine 100 is filled with ammunition cartridges that are pushed upward by an internal spring toward the top end 118 of the magazine. Feed lips 114 at the top of the magazine 100 position the cartridge for loading into the rifle.

[0003] The prior art magazine 100 is formed from two separate vertical halves 102 and 104. The feed lips 114 are formed at the top of each half 102, 104. The two halves are made from aluminum or another metal and are welded together along the vertical seam 106 to form a four-sided box. A separate metal floor plate 108 is inserted below the two halves 102, 104 and is held in place by metal tabs 110. The prior art magazine 100 also includes a magazine catch hole 112 near the top end of the magazine. The magazine catch hole 112 engages the rifle to secure the detachable magazine 100 to the rifle. When the magazine is inserted into the rifle's magazine well, an internal latch or lever inside the rifle engages the magazine catch hole 112 to retain the magazine 100 in the magazine well. A push button on the side of the rifle moves this lever or latch away from the catch hole 112 to allow the magazine to be freely removed from the rifle.

[0004] Prior art magazines have several design and operational flaws that contribute to poor performance during use. Prior art magazines 100 are easily deformed by side impacts as low as 200 pounds over an area of one square inch. Deformations in the walls of the magazine can obstruct the ammunition cartridges and spring inside. When the cartridges and spring are unable to move up and down freely inside the magazine, the magazine is inoperable as it can no longer reliably load the cartridges into the rifle. The feed lips 114 at the top of the magazine are also easily damaged when the magazine is dropped, stepped on, impacted, and/or worn from rough use. Deformation of the feed lips 114 can also render the magazine inoperable, as it will no longer be able to properly feed the cartridges into the rifle chamber.

[0005] Additionally, the small tabs 110 are the only mechanism holding the separate floor plate 108 in place. These tabs are exposed to rapid wear and damage and are under constant pressure from the compressed spring inside the magazine. When the tabs 110 fail, the floor plate 108 drops out of the magazine along with all the ammunition inside. Prior art magazines also suffer from failure of the spring as it repeatedly rubs up and down against the abrasive metal inside surfaces of the two halves 102, 104. When the spring fails, the cartridges inside can become wedged into place, and the magazine is unable to load them into the rifle. The abrasive metal surfaces of the magazine and its internal components require corrosion-proof coating to protect them from water, gun solvents and fluids, rust, and abrasive wear and tear. [0006] It is therefore desirable to provide a more reliable and robust magazine with a longer useful life.

SUMMARY OF THE INVENTION

[0007] The present invention relates to rifle magazines, and more particularly to an improved detachable magazine for a rifle. In one embodiment, the improved magazine has upper and lower portions molded from a high-impact polymer. Feed lips at the top of the upper portion of the magazine are optionally reinforced with stainless steel or another suitable metal. The molded lower portion includes an integral floor, instead of a separate floor piece. The upper and lower portions are bonded together with a high-strength adhesive. The upper and lower portions form a shoulder where they meet, and a resilient gasket is positioned on the shoulder to seal the magazine to the rifle magazine well when the magazine is inserted into the rifle. The use of a high-impact polymer reinforced with metal feed lips produces an impact-resistant, light-weight, and reliable magazine, and the shoulder and gasket provide a reliable seal against the rifle. [0008] In one embodiment of the invention, a detachable magazine for insertion into a rifle includes a first polymer portion and a second polymer portion bonded to the first polymer portion along a horizontal seam. The horizontal seam includes first and second overlapping surfaces of the first and second polymer portions. The first overlapping surfaces extend in a first plane, and the second overlapping surfaces extend in a second plane different from the first plane. In some embodiments, the second polymer portion is permanently bonded to the first polymer portion by adhesive.

[0009] In another embodiment, a magazine for a rifle includes an upper portion having a belt of increased thickness and a first surface extending below the belt, and a lower portion having an upper surface and an internal cavity defined by an interior surface. The upper and lower portions contact each other along first and second overlapping areas. The first overlapping area includes the first surface of the upper portion and the interior surface of the lower portion, and the second overlapping area includes a bottom surface of the belt and the upper surface of the lower portion. The upper and lower portions are bonded together along one or more of the first and second overlapping areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features and advantages of the present invention will become appreciated as the same become better understood with reference to the specification, claims and appended drawings wherein: [0011] FIG. 1 is a perspective view of a prior art magazine;

[0012] FIG. 2 is an exploded perspective view of an improved magazine in an exemplary embodiment of the invention;

[0013] FIG. 3a is a top perspective view of an improved magazine in an exemplary embodiment of the invention; [0014] FIG. 3b is a front view of the improved magazine of FIG. 3a;

[0015] FIG. 3c is a right side view of the improved magazine of FIG. 3a;

[0016] FIG. 3d is a rear view of the improved magazine of FIG. 3a;

[0017] FIG. 3e is a lower perspective view of the improved magazine of FIG. 3 a;

[0018] FIG. 4a is a top perspective view of an improved magazine in an exemplary embodiment of the invention;

[0019] FIG. 4b is a perspective view of a gasket for use with an improved magazine in an exemplary embodiment of the invention;

[0020] FIG. 5 is a lower perspective view an improved magazine in an exemplary embodiment of the invention; [0021] FIG. 6a is a front view of an improved magazine in an exemplary embodiment of the invention;

[0022] FIG. 6b is a front cross-sectional view of the improved magazine of FIG. 6a;

[0023] FIG. 7a is a perspective view of a top portion of an improved magazine in an exemplary embodiment of the invention; [0024] FIG. 7b is a perspective view of a bottom portion of the improved magazine of

FIG. 7a; and

[0025] FIG. 7c is a front view of the improved magazine of FIG. 7a.

DETAILED DESCRIPTION [0026] The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of a rifle magazine provided in accordance with the present invention and is not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the features of the present invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. As denoted elsewhere herein, like element numbers are intended to indicate like elements or features.

_V [0027] An improved magazine 200 according to an embodiment of the invention is shown in FIG. 2. In some embodiments, the improved magazine 200 meets the U.S. military performance specifications set out in solicitation #H92222-04-R-0001, the entire content of which is expressly incorporated by reference herein. Specifically, the improved magazine 200 can meet the reliability requirements of paragraph 3.2.3.10 of that document, and the rough handling requirements of paragraph 3.2.3.14.

[0028] The magazine 200 includes a lower portion 222 and an upper portion 220 that are adhered or otherwise bonded together. The two portions 220, 222 each have internal cavities defined by interior surfaces. Inside these two portions are a compressed spring or coil 244, a follower 242, and a feed lip box 240. The spring 244 pushes the follower 242 upward through the feed lip box 240 and toward the feed lips 214, 215 at the top of the magazine. Ammunition cartridges (see FIG. 3b) are loaded above the follower 242. The follower guides them up to the feed lips, which feed the cartridges into the rifle chamber. [0029] The upper and lower portions 220, 222 of the magazine fit together such that the surfaces 228a, 228b of the upper portion 220 overlap the surfaces 230a, 230b of the lower portion 222, creating an overlapping joint. A reinforcing belt 226 is molded in the upper portion 220 to add wall thickness to the upper portion 220 where it meets the lower portion 222. The belt extends around all sides of the upper portion 220. The belt allows the two portions to be bonded together in two planes ~ first along the vertical surface 228a of the upper portion extending below the belt, and second along the horizontal surface 228b on the bottom side of the belt 226. hi one embodiment, the two planes are perpendicular. The vertical and horizontal surfaces 228a, 228b of the top portion 220 overlap with the corresponding vertical or interior surface 230a and horizontal or upper surface 230b of the lower portion 222, creating two overlapping areas. [0030] In one embodiment, a suitable high-strength adhesive is applied to the surfaces 228a, 228b and/or the surfaces 230a, 230b, such as a self-curing, high-strength epoxy adhesive. The adhesive secures the two portions 220, 222 together along these overlapping surfaces 228, 230, providing a high strength bond, and, in some embodiments, providing a permanent bond. Alternatively, the two portions 220, 222 can be secured together along the overlapping surfaces 228, 230 by heat-welding, heat-sealing, heat-staking, laser welding, vibration welding, or other suitable methods. The two portions 220, 222 can also be secured together mechanically, such as by rivets, short screws, or other appropriate fasteners. The belt 226 provides additional wall thickness that can accommodate such a mechanical fastener. Although the belt is shown in Figure 2 on the upper portion 220, the belt 226 can be formed on the lower portion 222 instead. In such an embodiment, the belt operates in the same way described above, providing overlapping surfaces and additional wall thickness, only it is formed on the lower portion 222. [0031] The overlapping surfaces 228, 230 allow the two portions 220, 222 to be bonded together along two planes, creating an overlapping joint that is very strong and reliable. Because the two portions 220, 222 are upper and lower portions, rather than two side-by-side vertical portions, they can be designed to meet at the increased wall area of the belt 226. Vertical portions cannot meet along a joint with increased thickness, because a magazine with an increased thickness along a vertical seam would not fit into a standard rifle magazine well. The outer dimension of the upper portion of the magazine is constrained by the standardized size of typical rifle magazine wells. Moreover, the interior dimensions of the magazine are also constrained by the size of the ammunition cartridges that the magazine must accommodate. Thus, the upper portion of the magazine extending into the rifle magazine well is constrained by both interior and exterior dimensions, and the magazine cannot simply be increased in thickness. As a result, magazines utilizing vertical seams between two vertical halves cannot provide an area of increased thickness along the length of the vertical seam to strengthen the bond between the two vertical halves. By contrast, the present magazine can utilize the increased thickness of the belt 226 to strengthen the bond between the two portions 220, 222.

[0032] The lower portion 220 includes a molded floor 232. hi one embodiment, the molded floor 232 is an integral part of the molded polymer lower portion 222, not a separate piece. The molded, integral floor 232 eliminates the need for tabs, prongs, screws, or any other mechanism for attaching a separate floor piece to the magazine. As a result, the failure of the floor 232 is substantially reduced, as compared to the prior art magazines 100 that rely on small tabs 110 to hold the separate floor plate 108 in place against the substantial spring pressure inside the magazine. [0033] Prior art magazines often utilize a separate component, such as a floor plate or end cap, that is mechanically engaged to the four-sided magazine. This separate component is detachable and can be removed from the magazine to gain access to the spring and follower inside. However, these prior art magazines with mechanically engaged, detachable floor plates or end caps are prone to failure when they are dropped, as damage to the separate plate or cap can cause the mechanical engagement to fail. The separate floor plate or end cap then comes apart from the magazine, releasing the spring inside and causing all of the ammunition to fall out. These prior art magazines with separate, mechanically fastened portions are easily rendered inoperable when dropped, impacted, or otherwise damaged. In one embodiment, the present magazine provides an integral floor plate that is permanently bonded to the rest of the magazine, and is much more difficult to separate from the magazine. As a result, the spring is much less likely to pop out or come loose when the magazine is dropped or impacted. Unlike the prior art magazines, the present magazine is not intended to be disassembled once the two portions 220, 222 are bonded together. When bonded together, the magazine 200 is essentially a five-sided box, formed by the bonded upper and lower sections with the integral floor plate 232. By contrast, prior art magazine are essentially four- sided boxes with a separate floor piece or end cap. The five-sided box is much stronger than the four-sided box, and as a result the magazine 200 is stronger and more reliable. [0034] Of course, the improved magazine of the present invention can incorporate a separate floor plate instead of an integral plate if desired for a particular application.

[0035] In one embodiment, the two portions 220, 222 are molded out of a suitable high- impact polymer, such as Celstran, manufactured by Ticona, a division of the Celanese Corporation. The high-impact polymer improves the strength of the magazine and enables the magazine to withstand forceful impacts without deforming, cracking, splitting, or otherwise failing. When a magazine is loaded into a rifle and used during training, combat, or other exercises, the magazine is often subjected to impacts from rough handling and normal wear and tear. The increased strength of the polymer portions 220, 222 provides a magazine with a longer useful life. The use of a suitable polymer for the magazine portions 220, 222 also eliminates the need for corrosion-resistant coatings of the magazine. Prior art metal magazines require multiple corrosion-resistant coatings to protect the magazine from corrosion and to protect the internal parts of the magazine from the abrasive contact with the metal walls of the magazine. These corrosion coatings are unnecessary with the polymer magazine. [0036] Another advantage of the polymer magazine is that it can be molded in many different colors or combinations of colors. For example, it can be molded dark green, dark brown, light brown, or other colors to match the surrounding landscape and provide camouflage. The polymer lower portion 222 can even be made transparent so that the operator can see the number of cartridges remaining in the magazine when the magazine is in use inserted into a rifle. The lower portion 222 remains exposed outside of the rifle, so the operator can see the lower portion and, if it is transparent, can see how many rounds remain in the magazine. The polymer magazine also has a low infrared signature as compared to prior art metal magazines.

[0037] In one embodiment, the spring 244 is a metal spring coated with a suitable polymer coating such as a chromium silicon or a stainless steel spring that is polymer coated for corrosion resistance. The coating reduces the friction between the spring and the interior walls of the magazine portions 220, 222 and prevents the spring 244 from abrading or wearing down as it rubs against the interior walls. The polymer upper and lower portions 220, 222 also have a natural lubricity that contributes to a low coefficient of friction between the spring and the interior walls of the magazine. The coating makes the spring 244 less likely to weaken or warp from the constant rubbing contact with the interior walls. The coated spring 244 retains its shape and elasticity, and moves up and down easily to guide the follower 242 and the loaded cartridges up into the rifle. [0038] The follower 242 is constructed from glass-filled nylon (such as 33% glass reinforced nylon) or a suitable plastic. The follower 242 guides the ammunition cartridges upward toward the feed lips 214, 215 at the top of the magazine, evenly distributing the force of the compressed spring to the cartridges. The follower includes two vertical legs 246 on opposite ends of the follower, which prevent the follower from tilting or twisting inside the magazine. One or more grooves 256 are molded into the legs 246 to align the follower with one or more ridges 252 on the inside surface of the upper and lower portions 220, 222 of the magazine. The alignment of the groove 256 with the ridge 252 further prevents the follower 242 from tilting or wedging itself inside the magazine, and keeps the follower 242 properly oriented as it moves up and down in the magazine. The top raised surface 250 on the follower 242 positions the cartridges into the feed lips 214, 215 where they are fed into the rifle chamber. When the magazine is unloaded, the follower 242 can be manually depressed so that the magazine can be easily cleaned by flushing it with a jet of water. [0039] In one embodiment, the magazine 200 includes a feed lip box 240 made of a suitable metal, such as stainless steel. The metal feed lip box 240 includes two feed lips 214 that guide the cartridges into the rifle. The metal feed lip box 240 is attached to the inside surface of the upper portion, such as by over-moldeding into the polymer upper portion 220. To mold the two pieces together, the metal frame of the feed lip box 240 is inserted into a plastic injection mold, and a polymer is injected around it to form the upper portion 220. The circular sections 239 formed in the metal feed lip box 240 engage with the polymer mold of the upper portion 220 and prevent the two pieces ~ the upper portion 220 and the metal feed lip box 240 ~ from sliding relative to each other. The circular sections 239 lock the two pieces together in place. [0040] When the two pieces are molded together, the inside surface 221 of the upper portion 220 is covered by the metal feed lip box 240. The cartridges, follower 242, and spring 244 moving up and down inside the magazine 200 contact the metal inside surface 241 of the feed lip box 240 when they move into the upper portion 220 of the magazine. The inside surface 241 of the feed lip box includes a raised surface 253 that corresponds to the ridge 252 on the inside surface 221 of the top portion 220. This raised surface 253 also aligns with the groove 256 on the leg 246 of the follower 242, so that the follower 242 can slide smoothly up and down inside the feed lip box without tilting or jamming. In the lower portion 222 of the magazine, the cartridges, follower 242, and spring 244 directly contact the polymer inside surface 223 of the lower portion 222. [0041] The top portion 220 includes polymer feed lips 215 molded around the metal feed lips 214 of the feed lip box 240. The polymer feed lips 215 encase the outside of the metal feed lips 214, leaving the tops of the metal feed lips 214 exposed. A cartridge inside the upper portion 222 moves up against the metal inside surface 241 until it contacts the metal feed lips 214 at the top of the cartridge. [0042] The feed lips perform the important function of aligning the cartridges for loading into the rifle chamber. If the feed lips are deformed from rough handling or repeated impacts, or if the material forming the feed lips fails, the magazine can jam when the rifle attempts to load a cartridge from the feed lips. In the embodiment shown in Figure 2, the magazine 200 provides high-strength polymer feed lips 215 reinforced by tough metal feed lips 214. The reinforcement provided by the metal feed lips 214 protects the polymer upper portion 220 from deforming when it is heated and cooled, or cracking when it is dropped or impacted. The feed lips are subjected to high heat inside the rifle, where they load the cartridges into the rifle chamber, so the reinforcement provided by the metal feed lips 214 prevents the polymer upper portion 220 from wearing down or deforming. The metal feed lips are also heavier than the plastic portions 220, 222, so if the magazine is dropped, the sturdy metal feed Hp box

240 may fall forward and hit the ground first, preventing the plastic portions from cracking or splitting.

[0043] In addition to reinforcing the feed lips, the metal feed lip box 240 molded into the upper portion 220 also reinforces the walls of the upper portion 220. This reinforcement helps to prevent the magazine walls from swelling due to the pressure exerted by the spring 244 during repeated loading and unloading of the magazine. If the upper portion 220 swells, it may not be possible to insert it into the rifle, or it may become stuck inside the rifle instead of falling free when the operator tries to release it. Such metal reinforcement is less important in the lower portion 222. The lower portion 222 is not inserted into the rifle, and is not subjected to the increased heat and wear that the feed lips and upper portion are exposed to inside the rifle. Therefore, the improved magazine 200 utilizes the light-weight and high strength polymer for the lower portion 222, instead of using a heavier metal. The polymer lower portion 222 thus reduces the overall weight of the magazine compared to prior art metal magazines.

[0044] However, the metal feed lip box 240 is optional, and is not present in some embodiments. A polymer with suitable strength can be used to mold the upper portion 220, including the upper feed lips 215. hi such an embodiment, the reinforcement provided by the metal feed lip box 240 is not necessary, so the feed lip box is omitted. The resulting magazine with the polymer upper and lower portions 220, 222 is lightweight and strong.

[0045] An improved polymer magazine 300 according to an exemplary embodiment of the invention is shown in FIGs. 3a-3e. The magazine 300 is fully unloaded, as the follower 342 has reached the top end 318 of the magazine next to the feed lips 314, 315. The feed lip box 340 has been over-molded with the upper portion 320, with the metal feed lips 314 exposed at the top of the magazine around the edges of the polymer feed lips 315.

[0046] In FIG. 3a, the upper portion 320 is attached to the lower portion 322 at the horizontal seam 334. At this seam, the overlapping surfaces 228a, 228b and 230a, 230b of the upper and lower portions (shown in FIG. 2) are bonded by heat-welding or by adhering them together with a suitable adhesive, as described above. The horizontal seam 334 provides improved performance over prior art magazines which include a vertical welded seam 106 (shown in FIG. 1). The weld material used in the vertical welded seam 106 often has a different coefficient of thermal expansion than the metal used for the vertical halves 102, 104. When the magazine 100 is subjected to heat, the vertical seam 106 expands at a different rate than the halves 102, 104, causing the magazine to warp. By contrast, the adhesive or heat-sealed horizontal seam 334 expands at the same rate as the polymer portions 320, 322, thereby reducing the risk of warping. In addition, the bond at the seam 334 is just as strong as the polymer itself. In prior art magazines 100, the welded seam 106 is a weak point of the magazine that has lower strength than the metal halves 102, 104. The welded seam 106 is thus prone to failure after extended use, especially when the magazine is cyclically heated and cooled multiple times during combat, training, or other operations, causing the magazine 100 to expand and contract around the welded seam 106. [0047] As shown in FIG. 3b, the lower portion 322 of the improved magazine 300 has a curved contour, while the upper portion 320 is straight. The straight upper portion 320 is shaped to fit standard rifle magazine wells. The upper portion 320 is inserted into the rifle's magazine well until the top shoulder 327 of the belt 326 contacts the rifle. The belt 326 and lower portion 322 remain exposed outside of the rifle magazine well. The outer surface of the upper portion 320 is straight so that it can fit into standard rifle magazine wells. The lower portion 322 is curved to accommodate the tapered shape of the cartridges 316 loaded inside. Many cartridges 316 have a tapered end 317, which causes the cartridges to tilt toward each other at their tapered ends 317 when they are vertically stacked. The smooth curved shape of the interior surface of the lower portion 322 accommodates the tapered cartridges 316 and prevents them from becoming wedged or lodged inside the magazine. [0048] The improved magazine 300 can be manufactured to hold any desired number of rounds of cartridges 316. For example, the magazine 300 could be a 30 round magazine, or a 20 round magazine, or any other desired number of rounds. The size of the upper and lower portions 320, 322 can be increased or decreased to accommodate the desired number of cartridges 316. In one embodiment, the cartridges are 5.56 mm caliber cartridges. The magazine can also be manufactured to accept other cartridges of varying calibers.

[0049] In an exemplary embodiment of the invention, an improved magazine 400 also includes an optional gasket 458 resting on the shoulder 427 of the belt 426, as shown in FIGs. 4a-4b. The gasket 458 seals the space between the magazine 400 and the rifle when the magazine is inserted into the rifle. The upper portion 420 of the magazine is inserted into the rifle until the gasket 458 contacts the rifle. The shoulder 427 enables the rifle operator to feel when the magazine is fully inserted into the rifle. The gasket seals the interface between the rifle and magazine to prevent any dirt, water, fluids, or other debris from entering the rifle and possibly interfering with the loading of cartridges from the magazine into the rifle chamber. The gasket 458 and shoulder 427 can extend around all sides of the upper portion

420 to provide a complete seal. The gasket 458 can be passed over the top end 418 of the upper portion 420 and slid into place around the shoulder 427. In one embodiment, the gasket is 1/8 inch tall, although it can be taller or shorter. The gasket 458 can be constructed out of expanded vinyl acetate, silicon, or any suitable plastic, polymer, or foam.

[0050] In an exemplary embodiment, the gasket 458 is soft or resilient, so that it deforms or crushes against the rifle when the operator inserts the magazine into the rifle. The soft gasket 458 ensures a tight seal between the magazine and the rifle, adjusting for manufacturing tolerances that might otherwise leave a small gap between the magazine and the rifle's magazine well. When the rigid surfaces of the rifle and the magazine shoulder contact each other without a gasket, they can leave small gaps or cracks through which dust or debris can enter the rifle. The two rigid surfaces may also rattle against each other during operation. The gasket 458 provides a resilient surface between the magazine shoulder and the rifle, which can prevent rattling noises, provide an accommodating seal, and gently bring the rifle and magazine together.

[0051] In an exemplary embodiment of the invention, an improved magazine 500 includes a recess or indentation 560 formed in the integral floor 532 of the lower portion 522, as shown in FIG. 5. This recess 560 allows the magazine 500 to be more easily gripped from the bottom. Magazines are often inverted when they are inserted into pouches, packs, and other bags carried by the rifle operator, such that the floor 532 is facing upwards. When the operator wants to grab the magazine 500 to insert it into the rifle, the operator can use the recess 560 to more easily grip the magazine.

[0052] In another exemplary embodiment of the invention, an improved magazine 600 includes a molded plastic pull tab 636 coupled to the molded floor 632 of the lower portion 622, as shown in FIGs. 6a-6b. The pull tab 636 seals a drain hole 648 formed in the floor 632 of the magazine 600. The drain hole 648 allows water and debris to escape the interior cavity 624 of the magazine, but an exposed drain hole can also allow water and debris to enter the magazine. Therefore, the pull tab 636 seals the drain hole 648 to prevent any contaminants from entering the magazine and obstructing the operation of the spring, follower, and cartridges inside. If water or other contaminants do enter the magazine, for example when it is being loaded or stored or inserted into the rifle, the operator can pull down on the pull tab 636 in the direction of the arrow A in FIG. 6a. The water or other debris 638 inside the magazine can then escape through the drain hole 648, and exit the magazine. When the operator releases the pull tab, it snaps back into place against the molded floor 632, re-sealing the drain hole 648. The pull tab 636 can be made of any suitable flexible plastic.

[0053] The pull tab 636 is coupled to the molded floor 632 by inserting the fastener portion 662 of the pull tab 636 into a pull tab opening 664 formed in the floor 632. In the embodiment shown, the fastener portion 662 is shaped as a dart fastener, with outer tab portions 668. The fastener portion 662 and tab portions 668 compress as the fastener portion is squeezed through the opening 664, and the fastener portion springs back into shape when it enters the magazine cavity 624. When the outer tab portions 668 spring back into shape, they extend past the edges of the opening 664 and hold the pull tab 636 in place. These tabs 668 prevent the pull tab 636 from being removed from the magazine 600 even when the pull tab is pulled to expose the drain hole 648. The pull tab 636 can stretch to expose the drain hole 648, but it will remain attached to the magazine as the outer tabs 668 of the fastener portion 662 prevent the fastener portion 662 from sliding back through the opening 664. A few drops of adhesive may also be applied to the pull tab opening 664 in order to secure the pull tab to the magazine.

[0054] The pull tab 636 also provides a convenient grip for the rifle operator. Detachable magazines are often carried in pouches or bags with the floor 632 facing upwards. When the rifle operator needs to load the magazine, he or she has to grab the floor of the magazine in order to lift it out of the pouch or bag. Prior art floor plates can be difficult to grab as they do not provide an easy grip. The pull tab 636 is shaped to provide the operator with an easy and effective grip on the magazine. The operator can simply grip the molded pull tab 636 between two fingers and rapidly extract the magazine from the pouch or bag. The plastic pull tab is lightweight and durable, and does not make the magazine unnecessarily bulky or heavy. In addition, in the embodiment shown in FIG. 6a, the outside surfaces of the magazine are smooth, free of ribs, grooves, ridges, and sharp edges, so that the magazine can be easily and rapidly extracted from a pouch or bag. The pull tab 636 is attached to the floor of the magazine, rather than to the side walls of the magazine, so that the pull tab does not increase the width of the magazine and prevent it from fitting easily into a pouch or bag. Additionally, by attaching the pull tab to the floor of the magazine, there is no need for any mechanical fastener to extend through the side walls and potentially interfere with the movement of the spring and follower up and down inside the magazine. [0055] As shown in FIG. 6b, the walls of the lower portion 622 have a larger thickness tl than the thickness t2 of the walls of the upper portion 620. The increased thickness of the lower portion 622 increases the strength of that portion and protects it from impacts. The lower portion 622 is exposed outside of the rifle when the magazine 600 is inserted into the rifle, so the lower portion 622 is exposed to rough handling and side impacts. The upper portion 620 above the belt 626 is contained within the rifle, and thus protected from direct impacts. The upper portion 620 must be thin enough to fit inside standard rifle magazine wells, and the dimensions of the upper portion must be tightly controlled. Thus, the thickness tl is less than the thickness t2 of the lower portion. The upper portion of the improved magazine is shaped to fit inside any rifle that accepts a detachable magazine. [0056] Another embodiment of an improved rifle magazine according to the present invention is shown in FIGs. 7a-7c. In this embodiment, the vertical surface 728a of the upper portion 720 includes one or more tabs or projections 770 that extend outwardly from the surface 728a. The inside surface 723 of the lower portion 722 has one or more corresponding recesses 772. When the upper and lower portions are fitted together so that they can be heat sealed or adhered to each other, the tabs 770 snap into the recesses 772. The engagement of the tabs in the recesses holds the upper and lower portions together while the adhesive securing the two portions sets. As will be apparent, the tabs and recesses could be reversed such that tabs are formed in the lower portion and recesses in the upper portion. In addition, the tabs and recesses could be modified to be any suitable mating features that hold the two portions 720, 722 together. These mating features prevent the two portions from sliding apart while the adhesive or heat sealing is setting. The spring inside the magazine is under compression, so it will tend to force the two portions 720, 722 to separate if they are not attached to each other. Thus, the tabs and recesses snap together to prevent the spring from separating the portions 720, 722 while the adhesive sets (or while any other suitable bonding method is performed). [0057] An embodiment of the improved magazine of the present invention was subjected to stress tests to determine the magazine's performance. A prototype of the improved magazine was impact tested, and the resulting stresses on the upper and lower portions of the magazine were determined. These stresses were considerably lower than the stresses in prior art magazines during similar impact tests. The high-strength molded polymer portions can withstand rough handling and hard impacts without resulting in failure of the polymer portions or the horizontal seam. For example, the polymer magazine allows a side impact force of 550 pounds before failure occurs.

[0058] In another embodiment of the invention, a method of manufacturing an improved rifle magazine is provided. The method includes providing molds for injection molding of the two portions 220, 222. The mold for the upper portion 220 is straight, while the mold for the lower portion 222 is curved. The molds each include an insert that creates the hollow interior of each portion. A suitable polymer is injected into the molds and allowed to set, and then the molded portions are removed from the molds and the inserts from the molded portions, creating two molded polymer portions 220, 222. The use of two horizontal portions enables this molding process to create a straight upper portion that can be inserted into the rifle and a curved lower portion that accommodates tapered cartridges. It is very difficult to create a molded polymer piece that is hollow inside and that changes radius, as the piece that is inserted inside the mold to create the hollow interior has to be pulled out from inside the molded piece once the polymer has set. If the radius of the molded piece changes, it will be difficult if not impossible to remove this insert. The present two-piece design allows the magazine 200 to change curvature, with a straight upper portion 220 and curved lower portion 222. Thus, in one embodiment, the curved lower portion 222 has a constant radius of curvature. [0059] If the upper portion 220 includes the separate metal feed lip box 240, then the feed lip box 240 is first formed from a suitable metal, such as stainless steel. It is inserted into the mold for the upper portion 220, and the polymer is injected around the box 240. When the polymer sets, it creates an upper portion 220 molded around the feed lip box 240. [0060] When both molded portions 220, 222 are ready for assembly, the spring 244 and follower 242 are inserted inside the hollow interiors of the portions 220, 222. hi one embodiment, adhesive is applied around one or more of the surfaces 228a, 228b, 230a, 230b, and the upper and lower portions 220, 222 are then snapped together. The spring compresses inside the two portions, and the mechanical engagement of the tabs 770 and recesses 772 (described above with reference to Figures 7a-7c) holds the two portions together against the spring pressure while the adhesive sets. In other embodiments, a sealing method other than adhesive may be used, as described previously.

[0061] As described above, the present invention provides embodiments of an improved rifle magazine and method of making an improved magazine with durable polymer portions and a design that provides improved performance over the prior art.

Claims

WHAT IS CLAIMED IS:

1. A detachable magazine for insertion into a rifle, comprising: a first polymer portion; and a second polymer portion bonded to the first polymer portion along a horizontal seam, wherein the horizontal seam comprises first and second overlapping surfaces of the first and second polymer portions, the first overlapping surfaces extending in a first plane and the second overlapping surfaces extending in a second plane different from the first plane.

2. The magazine of claim 1 , wherein the second polymer portion is permanently bonded to the first polymer portion along the horizontal seam.

3. The magazine of claim 2, wherein the second polymer portion is permanently bonded to the first polymer portion by adhesive.

4. The magazine of claim 1, further comprising a belt of increased thickness on one of the first and second polymer portions, wherein the belt forms one of the overlapping surfaces.

5. The magazine of claim 1 , wherein one of the first and second polymer portions comprises a belt of increased thickness, and wherein one of the first overlapping surfaces abuts a side of the belt.

6. The magazine of claim 1 , wherein one of the first and second polymer portions is curved along an interior surface.

7. The magazine of claim 6, wherein the other of the first and second polymer portions is straight along an exterior surface.

8. A magazine for a rifle, comprising: an upper portion having a belt of increased thickness and a first surface extending below the belt; and a lower portion having an upper surface and an internal cavity defined by an interior surface, wherein the upper and lower portions contact each other along first and second overlapping areas, the first overlapping area comprising the first surface of the upper portion and the interior surface of the lower portion, and the second overlapping area comprising a bottom surface of the belt and the upper surface of the lower portion; wherein the upper and lower portions are bonded together along one or more of the first and second overlapping areas.

9. The magazine of claim 8, wherein the interior surface of the lower portion is curved.

10. The magazine of claim 8, wherein the lower portion comprises an integral floor.

11. The magazine of claim 10, wherein the integral floor comprises a drain hole.

12. The magazine of claim 11 , further comprising a resilient pull tab attached to the integral floor for covering the drain hole.

13. The magazine of claim 8, further comprising a shoulder formed along a top surface of the belt.

14. The magazine of claim 13, wherein the shoulder extends around all sides of the upper portion.

15. The magazine of claim 13, further comprising a gasket on the shoulder.

16. The magazine of claim 15, wherein the gasket comprises a resilient material.

17. The magazine of claim 8, wherein the upper portion comprises an internal cavity defined by an interior surface, and wherein the magazine further comprises a feed lip box attached to the interior surface of the upper portion.

18. The magazine of claim 17, wherein the feed lip box comprises metal.

19. The magazine of claim 17, further comprising a follower movable inside the internal cavity and a spring urging the follower toward a top of the magazine.

20. The magazine of claim 8, wherein the upper and lower portions comprise a polymer.

21. The magazine of claim 8, wherein the upper and lower portions are adhered to each other along one or more of the first and second overlapping areas.

22. The magazine of claim 8, wherein the upper and lower portions are heat-sealed to each other along one or more of the first and second overlapping areas.

23. The magazine of claim 8, wherein the first overlapping area extends in a first plane and the second overlapping area extends in a second plane different from the first plane.

24. The magazine of claim 23, wherein the upper and lower portions are permanently bonded together along both the first and second overlapping areas.

25. The magazine of claim 8, wherein the first surface of the upper portion and the interior surface of the lower portion comprise one or more matching tabs and recesses.

26. A detachable magazine for insertion into a rifle, comprising: an upper polymer portion having a belt of increased thickness and a first vertical surface extending below the belt; a shoulder formed between the upper portion and a top surface of the belt, the shoulder extending around all sides of the upper portion; a gasket on the shoulder; a lower polymer portion having an upper surface, an integral floor plate, and an internal cavity defined by an interior surface; a drain hole formed in the floor plate; and a resilient pull tab attached to the floor plate for covering the drain hole, wherein the upper and lower portions overlap along a first overlapping area comprising the first vertical surface of the upper portion and the interior surface of the lower portion, and along a second overlapping area comprising a bottom surface of the belt and the upper surface of the lower portion, and wherein the upper and lower portions are adhered together along one or more of the first and second overlapping areas.