Patent Description:
Currently, many firearm ammunition magazines utilize some type of follower assembly, typically along with a spring-based pushing mechanism, to feed ammunition from the magazine into a firearm. The follower assembly is generally situated below an ammunition cartridge/round stack and is configured to push the cartridges along a path that exits the magazine through an open end of the magazine, often called the "feed end," which interfaces with a firearm. Specifically, in drum magazines, the feed end may be situated at the top of a feed tower, the feed tower attaching to a drum body that typically stores cartridges along a winding track with an overall spiral shape.

In some instances, drum magazines are specifically designed to interface with handguns (e.g., the SGM Tactical Glock <NUM> <NUM> Round Drum Magazine and the RWB Glock <NUM> <NUM> Round Drum Magazine) or carbines using pistol-type cartridges (e.g., H&K UMP45, Kel-Tec SUB-<NUM>, Rock River Arms LAR-<NUM> CAR A4). Such firearms may also include a slide mechanism, most commonly seen in semi-automatic handguns, which may be configured to interface with a bolt or slide lock-back mechanism, sometimes called a slide stop. Slide lock-back mechanisms may be engaged when a magazine has expended all of its cartridges providing a visual indicator that the magazine is empty as well as assisting in the reloading process.

Some firearms, such as the GLOCK, include a ramped underlug feature on the slide. In some cases, this underlug may be located directly above the round or cartridge and may act on the magazine round stack when the weapon is cycled, forcing the cartridges back down into the magazine. In order for this to occur, the round stack in the magazine must be able to move away from the chamber, or down into the magazine (or against the spring pre-load). In some circumstances, the force needed to overcome the primary spring pressure (i.e., generated by the spring-based pushing mechanism, for instance, a torsional spring in a drum magazine body) may be greater than the downward force produced by the weapon system (i.e., after the weapon is fired and the action is cycled). Hence, drum magazines, and other styled magazines with significant primary spring pressure can be incompatible with or problematic when used with firearms having an underlug on the slide.

Patent Publication No. <CIT> discloses a firearm cartridge feeding system comprising a multiple segment body or housing that contains a spiral channel, clutch mechanism pocket and a spring drive compartment which supports the storage of firearm cartridges and the arrangement of a drive system for feeding the firearm cartridges to the feed lips. Patent Publication No. <CIT> discloses a device for modifying an existing high capacity magazine to reduce the friction between the bolt and the cartridges and assure more reliable feeding, by biasing the cartridge into the feed position in a manner independent of the magazine's primary spring pressure. Patent Publication No. <CIT> discloses a magazine rifle, the magazine provided with resilient means to engage at least one cartridge case and attached to exert a force on the cartridges directly transverse to the mean longitudinal plane of the rifle. Patent Publication No. <CIT> discloses a cartridge magazine for firearms wherein the successive rounds of ammunition are moved to a feeding position by the action of a spring loaded follower.

The following presents a simplified summary relating to one or more aspects and/or embodiments disclosed herein. As such, the following summary should not be considered an extensive overview relating to all contemplated aspects and/or embodiments, nor should the following summary be regarded to identify key or critical elements relating to all contemplated aspects and/or embodiments or to delineate the scope associated with any particular aspect and/or embodiment. Accordingly, the following summary has the sole purpose to present certain concepts relating to one or more aspects and/or embodiments relating to the mechanisms disclosed herein in a simplified form to precede the detailed description presented below.

The present invention is defined by a firearm magazine according to claim <NUM>. Some aspects of the disclosure may be characterized as a firearm magazine, comprising a body and a feed tower. The feed tower may be configured to house one or more cartridges and may comprises a feed end, a base end, and one or more leaf springs. The one or more leaf springs may be positioned within the feed tower and may be configured to bias the one or more cartridges through the feed tower either towards the feed end or base end of the feed tower. The body may be coupled to the base end of the feed tower and may be configured to receive the one or more cartridges.

Other aspects of the disclosure may be characterized as a leaf spring system. The system may comprise one or more leaf springs which may comprise an inner edge, an outer edge, and a channel. The inner edge may comprise a ramped surface. The channel may be formed on the outer edge by vertical sections and may be shaped and sized to be secured over a rail in an interior of a feed tower. One or more of the vertical sections and the outer edge may be in contact with an interior surface of the feed tower; and a curved section may be positioned between the inner edge and the outer edge and form a C-shaped curve in the one or more leaf springs.

Furthermore, for the purpose of this disclosure, the terms "front" and "distal" shall refer to a side or direction associated with a direction of intended fire; for example, in <FIG>, the front or distal side is towards the left. When referencing pivoting or rotating components, the term "distal" shall refer to a section of the component that is distant from the pivot point, while the term "proximal" shall refer to a section of the component approaching the pivot point. Similarly, the terms "back", "rear", or "proximal" shall be associated with the intended bracing of a weapon, or the intended pivot point of a pivoting or rotating component. Moreover, for the purpose of this document, the term "cartridge" should be understood to include generally ammunition that can be magazine-fed, such as, for example, shotgun cartridges, grenade cartridges, and any other ammunition packaging a bullet or shot, a propellant substance and a primer within a case that is made to fit within a firing chamber of a firearm. Furthermore, for the purpose of this disclosure, the terms "spiral" and "generally spiraled" are meant to include any feature generally winding about a fixed point at a continuously and/or discontinuously increasing distance.

There is currently a need for a mechanism for a feed tower assembly that can facilitate the downward translation of the round stack in a magazine, such as a drum magazine, when a feed end of the magazine interfaces with a ramped underlug of the firearm. As described above, some firearm magazines comprise follower assemblies that can interface with a slide lock-back mechanism to lock the slide in a slide-backward position when the magazine no longer contains any ammunition cartridges. According to aspects of the present disclosure, the herein disclosed feed tower assembly mechanism may be capable of permitting any of closed-bolt (or slide-forward) or open-bolt (or slide-backward) magazine insertion into the weapon. In other words, a magazine can be inserted into a firearm with an underlug-allowing some rounds in the stack to be pushed downward by the underlug even when the primary magazine spring pressure exceeds the pressure from the underlug. This is made possible by one or more leaf springs arranged toward a base end of the feed tower that can flex outward to widen the round stack in the vicinity of the one or more leaf springs and thereby allow the round stack in the feed tower to compress even if this force is insufficient to compress or wind the primary magazine spring. In other words, the leaf springs currently disclosed allow the round stack to be pushed downward in the tower without imparting much if any force on rounds in a drum. In one non-limiting example, a pair of leaf springs nested opposite each other on the right and left side of the round stack (arranged on opposing long edges of the cartridges) may be provided. It should be noted that, other mechanisms, besides leaf springs, are contemplated in different embodiments. Further, more or less than two leaf springs may be utilized in some embodiments.

<FIG> illustrates an example of a drum magazine <NUM> with a feed tower <NUM>, a drum body <NUM>, a lever <NUM>, and one or more leaf springs <NUM> at or near the base of the feed tower <NUM>. The drum magazine <NUM> may be configured to hold a plurality of cartridges <NUM>. For instance, the drum magazine <NUM> may be configured to hold <NUM> to <NUM> or more cartridges, such as in a single-stack design having a generally spiraled stack configuration inside the drum body <NUM>. While not shown, in some cases, the drum body <NUM> may comprise a torsional spring configured to bias the cartridges in the drum magazine through the feed tower <NUM> and towards the feed end of the magazine. <FIG> shows more clearly the leaf springs <NUM>-a and <NUM>-b, where the leaf springs <NUM> are nested opposite each other on the right and left side of the long edges of cartridges <NUM> in the feed tower <NUM>. It should be noted that, <FIG> depicts the leaf springs <NUM>-a and <NUM>-b in an unflexed position. In this position, the inner edges of the leaf spring may be parallel or substantially parallel an edge of the round stack between the one or more leaf springs or parallel or substantially parallel to a plane passing through the round stack, and may or may not be in contact with the cartridges (e.g., the leaf springs and cartridge edges may be separated by a small gap). The space between the leaf springs <NUM>-a and <NUM>-b can be such that the round stack between them is considered "single stack" while being double stack or single stack angled between the leaf springs <NUM>-a and <NUM>-b and the feed end. <FIG> illustrates a rear view of the drum magazine <NUM>. Further, <FIG> illustrates a close-up view of the feed tower <NUM>, showing the leaf springs <NUM> at the base of the feed tower. Again, one sees that the leaf springs <NUM>-a and <NUM>-b force the cartridges into a common alignment while between the leaf springs <NUM>-a and <NUM>-b and that the cartridges are alternately angled relative to each other through a remainder of the round stack.

While <FIG> illustrate one embodiment of leaf springs that allow the round stack to be pushed downward in the tower without imparting much if any force on rounds in a drum, other leaf springs variants can also be implemented. Some non-limiting examples are shown in <FIG>.

<FIG> illustrate an example of a leaf spring system <NUM> comprising one or more leaf springs <NUM> (e.g., leaf springs <NUM>-a, <NUM>-b), according to an alternate embodiment of the present disclosure. The leaf springs <NUM> may implement one or more aspects of the leaf springs <NUM>, or any other of the other leaf springs described throughout this disclosure. In some examples, each of the leaf springs <NUM> may comprise an inner edge <NUM>, a hairpin section <NUM>, and a clip <NUM> having an opening <NUM>. In some cases, the hairpin section <NUM> may comprise a protrusion <NUM> that is configured to be parallel or substantially parallel to the inner edge <NUM> when the leaf spring <NUM> is an unflexed position. In some cases, the leaf spring system <NUM> may be configured to mount to an interior of the feed tower using the clip <NUM>. In some cases, the leaf springs <NUM> may be composed of a material, such as metal (e.g., steel, stainless steel, steel alloy or another alloy, aluminum, etc.), a polymer (e.g., plastic), or any other applicable material. In some embodiments, the leaf spring system <NUM> may be locked into position within the magazine body (e.g., inside feed tower <NUM> in <FIG>) when the magazine is assembled, as shown in <FIG> and <FIG>. The leaf spring system <NUM> may or may not be removable after magazine assembly. In some cases, the leaf springs <NUM> may be mounted to an interior of the feed tower <NUM>, as shown in <FIG>. <FIG> illustrates a pair of leaf springs <NUM> nested opposite each other in the interior of the feed tower <NUM>. In some embodiments, the opening in the clip <NUM> may be shaped and sized to receive (or clamp over) a rail <NUM> in the interior of the feed tower <NUM>. Further, the feed tower may comprise a gap <NUM> (shown in <FIG>) between the rail <NUM> and the body (or inner sidewall) of the feed tower. In some cases, at least a portion (e.g., an inner surface) of the channel <NUM> may be received within the gap <NUM>, while another surface of the channel (e.g., a surface adjacent the inner edge <NUM>) may be pushed against a front face <NUM> of the rail <NUM>. In this way, the leaf spring <NUM> may be securely mounted to an interior of the feed tower <NUM>. In some embodiments, the inner edge of the leaf spring <NUM> may be separated from the body of the feed tower by a gap, which may allow it flex outwards when the weapon is cycled, and the cartridge or round stack is pushed down into the magazine. In some embodiments, the leaf spring <NUM> may be configured to flex or bend between an unflexed and a flexed configuration, further described in relation to the figures below.

<FIG> illustrates an example of a leaf spring system <NUM> comprising one or more leaf springs <NUM>, according to an embodiment of the present disclosure. In this example, the leaf springs <NUM> are in an unflexed position. As seen, when in an unflexed position, the leaf springs <NUM> are substantially parallel to a vertical axis <NUM> through the feed tower <NUM> and/or one or more rounds/cartridges in the feed tower. In some examples, the leaf springs <NUM> may not be in contact with the cartridges in the feed tower <NUM> when in an unflexed position. For instance, as shown, a small gap may be present between the leaf springs <NUM> and the cartridge edges. <FIG> illustrates a front view of the leaf spring system <NUM>, previously described in relation to <FIG>. In some embodiments, the leaf springs <NUM> may be substantially V-shaped or U-shaped (shown in further detail in <FIG>). Further, the leaf springs <NUM> may be made of flat sheets of metal (e.g., steel, stainless steel, aluminum, an alloy, etc.), a polymer (e.g., plastic), or any other semi-rigid material.

Turning now to <FIG> and <FIG>, which illustrate detailed views of the leaf springs <NUM>. As seen, each leaf spring <NUM> may comprise an inner edge <NUM> (i.e., adjacent the cartridge edges in the magazine), an outer edge <NUM>, and a curved section <NUM>. As seen, in some cases, one or more of the inner edge and the outer edge may comprise one or more ramped or angled surfaces. In some examples, the outer edge <NUM> may comprise a clip, the clip having one or more inward protrusions <NUM> facing towards the inner edge <NUM>, and a planar surface <NUM>. The planar surface may be substantially parallel to the inner edge <NUM> when the leaf spring <NUM> is in an unflexed position. Furthermore, the inner edge <NUM> may comprise an outward bend <NUM> (also referred to as ramped surface <NUM>), the outward bend <NUM> or ramped surface directed away from a vertical axis (e.g., shown as vertical axis <NUM> in <FIG>) passing through a center of the feed tower.

In some examples, the leaf springs <NUM> may be configured to flex, for instance, during downward movement (i.e., away from the barrel) of the round stack in the feed tower. In some weapon systems, such as the GLOCK pistol, the slide may comprise a ramped underlug. This ramped underlug may be located directly above the topmost cartridge in the feed tower and may force the cartridges back down into the magazine, for instance, when the weapon is cycled. In some embodiments, the inner edges <NUM> of the leaf springs <NUM> may be configured to flex outward as the cartridge stack is pushed downward into the magazine, allowing a bottom of the cartridge stack to spread out or expand and effectively give the cartridge stack more room to traverse downward without having to compress the magazine's primary spring (i.e., put pressure on rounds below the leaf springs, such as in a drum portion of the magazine).

<FIG> and <FIG> illustrate the mounting of the leaf springs <NUM> within an interior of the feed tower <NUM>. As seen, the feed tower <NUM> may comprise a rail section <NUM>, where at least a portion of the rail section is separated from the body of the feed tower by a gap <NUM>. In some embodiments, the planar surface <NUM> may be shaped and sized so that it can be inserted (or received) within the gap <NUM>, while the inward protrusions <NUM> may rest or be supported over a horizontal section of the rail <NUM>. Further, at least a portion of the curved section <NUM> may be in contact with an interior face or edge of the feed tower, which may also help securely mount the leaf springs to the inside of the feed tower. In some cases, the horizontal section of the rail <NUM> over which the inward protrusions <NUM> rest may comprise an anti-slip material (e.g., shown by the grip strip on rail <NUM> in <FIG>), which may prevent the leaf springs <NUM> from sliding within the feed tower <NUM> as the cartridge stack is pushed up or down.

<FIG> and <FIG> illustrate another embodiment of a leaf spring <NUM>. The leaf spring <NUM> may implement one or more aspects of the leaf spring <NUM>, previously described in relation to <FIG>. As seen, the leaf spring <NUM> may comprise an inner edge <NUM>, a ramped surface <NUM>, a curved section <NUM>, an outer edge <NUM>, and a channel <NUM> formed by vertical sections <NUM> and <NUM>. In some cases, the channel <NUM> may be shaped and sized such that it may be secured over a rail <NUM> in an interior of the feed tower. For instance, <FIG> illustrates a pair of leaf springs <NUM> nested opposite each other and mounted to an interior of the feed tower. In this case, the rail <NUM> resembles an inward protrusion into the feed tower and comprises two horizontal sections extended inward into the feed tower, the two horizontal sections connected by a vertical section. As shown, the leaf springs <NUM> may be clamped or clasped over the rail <NUM> using one or more of the channel <NUM>, and the vertical sections <NUM> and <NUM>. In some examples, one or more of the vertical sections <NUM>, <NUM>, and the outer edge <NUM> of the leaf spring <NUM> may be in contact with the interior of the feed tower.

<FIG> and <FIG> illustrate leaf springs <NUM> in a flexed position, for instance, during downward movement of the cartridge stack in the feed tower. As seen, during downward movement, one or more cartridges in the stack may come into contact with the outward bends <NUM> of the leaf springs. The outward bends <NUM> may comprise a ramped surface angled away from a center of the feed tower. Such a design may facilitate the downward translation of the round stack by forcing the inner edge <NUM> (see <FIG>) away from the cartridges and allowing expansion room for a portion of the stack between the leaf springs. As seen, the inner edge <NUM> of a leaf spring <NUM> may be longer than its outer edge <NUM>, which may serve to magnify the downward force applied to the cartridge stack when the weapon is cycled. For instance, the difference in length between the inner and outer edges may assist in preventing the flexed leaf springs <NUM> from unflexing by the upward force generated on the cartridge stack from the primary magazine spring or spring preload (e.g., torsional spring), for instance, in a drum body. In some aspects, the downward force required to push the cartridges down into the drum portion may be lower with the leaf springs of the present disclosure, as opposed to when such leaf springs are not present. After the weapon has been cycled, the leaf springs <NUM> may be configured to return to the unflexed configuration.

<FIG> and <FIG> illustrate leaf springs <NUM> in a flexed position, for instance, during downward movement of the cartridge stack in the feed tower. In some examples, the leaf springs <NUM> may be designed to operate in a similar manner as the leaf springs <NUM>, previously described in relation to <FIG> and <FIG>. One can see that in the flexed position the round stack has greater room to expand between the leaf springs and this effectively allows downward movement of the stack when the magazine is loaded into a firearm in a bolt-closed state, while not putting undue pressure on rounds in the drum (below the leaf springs).

<FIG> and <FIG> illustrate leaf springs <NUM> and <NUM>, respectively, according to an alternate embodiment of the disclosure. In these examples, the leaf springs <NUM> and/or <NUM> may be composed of a flexible plastic or another applicable polymer, as opposed to metal (e.g., stainless steel, steel alloy, etc.) seen in the previous designs. In some cases, the leaf springs <NUM> and/or <NUM> may implement one or more aspects of any of the other leaf springs or leaf spring systems described herein. For instance, leaf spring <NUM> may be similar or substantially similar to the leaf spring <NUM> previously described in relation to <FIG>, <FIG>, <FIG>, and/or <NUM>, and may include one or more of an inner edge <NUM>, an outer edge <NUM>, a curved section <NUM>, one or more vertical sections <NUM>, <NUM> on the outer edge <NUM>, a channel formed between the vertical sections <NUM>, <NUM>, and a ramped surface or outward bend <NUM> on the inner edge <NUM>. In some cases, one or more of the vertical sections <NUM>, <NUM>, and the channel <NUM> may be used to clip or mount the leaf spring <NUM> to an interior of a feed tower, for instance, at the base of the feed tower.

<FIG> illustrates a pair of leaf springs <NUM>, which may be similar or substantially similar to the leaf spring(s) <NUM> previously described in relation to <FIG>, <FIG>, and/or <NUM>. As shown, each leaf spring <NUM> may comprise an inner edge <NUM> (i.e., adjacent the cartridge edges in the magazine), an outer edge <NUM>, and a curved section <NUM>. As seen, in some cases, one or more of the inner edge and the outer edge may comprise one or more ramped or angled surfaces. In other cases, the inner edge and/or the outer edge may also comprise one or more irregular surfaces (e.g., dips, irregular slopes, etc.), for instance, as seen along the top surface of the outer edge <NUM>. In some examples, the outer edge <NUM> may comprise a clip, the clip having one or more inward protrusions <NUM> facing towards the inner edge <NUM>, and a planar surface <NUM>. The planar surface may be substantially parallel to the inner edge <NUM> when the leaf spring <NUM> is an unflexed position. Furthermore, the inner edge <NUM> may comprise an outward bend <NUM> (also referred to as ramped surface <NUM>), the outward bend or ramped surface directed away from a vertical axis (e.g., shown as vertical axis <NUM> in <FIG>) passing through a center of the feed tower. It should be noted that, the leaf springs <NUM> and/or <NUM> may be mounted in a similar manner to the leaf springs <NUM> and/or <NUM>, respectively, described in relation to the preceding figures. Additionally, or alternatively, the leaf springs <NUM> and/or <NUM> may operate in a similar manner to any of the leaf springs or leaf spring systems described herein.

<FIG> illustrates an embodiment of the present disclosure that includes a first "dummy cartridge" <NUM> of a follower assembly <NUM>. For ease of illustration, the feed tower has not been shown in this example. However, <FIG> depicts the leaf springs <NUM> that are configured to be mounted in the interior of the feed tower (e.g., using a leaf, such as leaf <NUM> in <FIG>). The leaf spring(s) <NUM> may be similar or substantially similar to the leaf springs <NUM> or any of the other leaf springs described throughout this disclosure. As seen, the first dummy cartridge <NUM> of the follower assembly <NUM> may have a platform <NUM> configured to interface with a cartridge (not shown), which may be the last cartridge of a drum magazine. The platform <NUM> (also shown as platform <NUM> in <FIG>) may be on a top-facing side of the first dummy cartridge <NUM> (also shown as first dummy cartridge <NUM> in <FIG>) and may be configured to interface with a cartridge at an angle relative to a longitudinal axis of a feed tower of the magazine. This angle may include front to back slope as well as side to side slope. For instance, <FIG> and <FIG> show more clearly the front to back slope, while <FIG> shows both the front to back slope, as well as the side-to-side slope. The front to back slope may bias the first dummy cartridge <NUM> towards a rear of the magazine when a force is applied (e.g., via a spring in the drum body) to the first dummy cartridge <NUM> that pushes or pulls it in an upward direction through the tower of the magazine. The side-to-side slope, in conjunction with a resistive force from the last cartridge, may bias the first dummy cartridge <NUM> toward one side (e.g., a left side) of the magazine. This bias (e.g., leftward bias) allows a protruding heel (e.g., shown as protruding heel <NUM> in <FIG>) to engage a flange of a bolt lock-back mechanism, where such engagement might not occur without this leftward movement of the first dummy cartridge <NUM> (also shown as first dummy cartridge <NUM> in <FIG>). The leftward movement can include either or both of rotational and translational movement. The bolt lock-back mechanism (often used in a rifle or carbine) referred to throughout this application has similar function and structure to a slide lock-back mechanism (often used in a pistol), and thus for purposes of this disclosure, a slide lock-back mechanism can be used anywhere that a bolt lock-back mechanism is referenced.

In some cases, the first dummy cartridge <NUM> may also have a stop <NUM> configured to interface with a surface near the feed end of the magazine. The stop <NUM> may have a substantially planar forward-facing surface and may protrude from one side (e.g., the left side) of the first dummy cartridge <NUM>. The forward-facing surface may form an angle relative to the platform <NUM>. The stop <NUM> may be configured to cause a front <NUM> of the first dummy cartridge <NUM> to kick up when the stop <NUM> interfaces with the surface near the feed end of the magazine. The stop <NUM> may interface with the surface near the feed end of the magazine when no cartridges remain in the magazine. In some embodiments, the front <NUM> of the forward-facing side of the first dummy cartridge <NUM> may also have a protruding heel <NUM> extending sideways from front <NUM> of the platform <NUM>, which may enable the first dummy cartridge <NUM> to better interface with the slide lock-back interface or mechanism of some firearms, particularly when the stop <NUM> causes the front <NUM> of the forward-facing side of the first dummy cartridge <NUM> to kick up. In other embodiments, the stop <NUM> may protrude from a different side of the first dummy cartridge <NUM>, such as the right side. In other embodiments, the stop <NUM> may have a non-planar forward-facing surface, such as a curved or irregular surface, configured to interface with a surface near the feed end of the magazine. In other embodiments, the stop <NUM> may be configured to cause the top of the forward-facing side of the first dummy cartridge <NUM> to kick down when the stop <NUM> interfaces with a surface near the feed end of the magazine. In other embodiments, the heel <NUM> may extend sideways from the top of the platform <NUM>. The kicking up of the front <NUM> of the forward-facing side of the first dummy cartridge <NUM> caused by the stop <NUM>, along with continued upward pressure on the first dummy cartridge, for instance, from a follower spring below, may assist in directing force from the protruding heel <NUM> into a bolt lock-back mechanism.

In some embodiments, the platform <NUM> may be configured to partially protrude from the feed end of the magazine when no cartridges remain in the magazine. The platform <NUM> may be substantially flat and planar, though angled; however, in other embodiments the platform <NUM> may have a curved or irregular surface (not shown) so as to provide an alternative interfacing with a cartridge. In other embodiments, the platform (e.g., platform <NUM> in <FIG>, platform <NUM> in <FIG> and <FIG>) may be configured to bias the first dummy cartridge (e.g., first dummy cartridge <NUM>, first dummy cartridge <NUM>) in a different direction than that shown in <FIG>. In yet other cases, the platform may not bias the first dummy cartridge. However, the platform <NUM> or <NUM> biasing shown in <FIG> may be preferable to better align with and engage a slide lock-back interface or mechanism in some handguns or other firearms.

The first dummy cartridge <NUM> can also include a bolt ramp <NUM> (also referred to as pistol slide ramp <NUM>), which is angled relative to a direction of travel of the bolt or the pistol slide. In this way, when the bolt or pistol slide impinges on the first dummy cartridge <NUM>, the bolt contacts this curved and/or angled bolt ramp <NUM> and causes a downward pressure on the first dummy cartridge <NUM> that pushes the follower stack down and out of the way of the bolt allowing the bolt to move forward across the platform <NUM> without jamming. As described above, some weapon systems, such as the GLOCK pistol system, feature a ramped underlug feature on the pistol slide. In some cases, the platform <NUM> and/or angled ramp <NUM> may be configured to interface with this ramped underlug feature on the pistol slide, which may facilitate in forcing the follower back down into the magazine when the weapon is cycled. Further, the combination of the platform <NUM>, angled ramp <NUM>, and/or the leaf springs (e.g., shown as leaf springs <NUM> in <FIG>) may facilitate in translating the forward force from the pistol slide into sufficient downward force (i.e., to overcome the follower spring preload), thus allowing the follower to retract in the magazine. In some cases, the leaf springs may return to an unflexed position after the weapon has been cycled.

The first dummy cartridge <NUM> (also shown as first dummy cartridge <NUM> in <FIG>) may also have a cartridge-shaped portion <NUM> (also shown as cartridge-shaped portion <NUM>) configured to interface with the magazine in a similar fashion to an actual cartridge. The cartridge-shaped portion <NUM> may be of a similar shape to the actual cartridges used in the magazine and may be positioned on a bottom-facing side of the first dummy cartridge <NUM>. The cartridge-shaped portion <NUM> may enable the first dummy cartridge <NUM> to interface with the mechanisms of the magazine, such as a cartridge alignment and/or a cartridge moving mechanism, which may allow the first dummy cartridge <NUM> to move through the magazine in a fashion similar to an actual cartridge. In other embodiments, the cartridge-shaped portion <NUM> may be positioned on the bottom-facing side or in the middle of the first dummy cartridge <NUM>. In other embodiments, the first dummy cartridge <NUM> may not include a cartridge-shaped portion <NUM>.

The first dummy cartridge <NUM> may be part of a follower assembly (e.g., shown as follower assembly <NUM> in <FIG> and <FIG>) in a variety of magazine types, such as box or drum magazines; however, the first dummy cartridge <NUM> may be configured, for example by its dimensions and shape, to traverse a non-linear track, such as the winding tracks often found in drum magazines, while producing minimal frictional forces and maintaining proper alignment so as to avoid causing blockages or jams (e.g., avoiding nose diving of cartridges). In one embodiment, a follower spring can be a torsional spring coupled to a rotatable arm and may be positioned inside the drum body (e.g., drum body <NUM> in <FIG>).

<FIG> illustrates an embodiment of the present disclosure that includes a follower assembly <NUM> with a plurality of linked dummy cartridges <NUM> that are linked to a first dummy cartridge <NUM>. Each of the linked dummy cartridges <NUM> may be of a similar shape to the actual cartridges or rounds used in the magazine enabling the linked dummy cartridges <NUM> to interface with the mechanisms of the magazine, such as the cartridge alignment and cartridge moving mechanisms, which may allow the linked dummy cartridges <NUM> to move through the magazine in a fashion similar to an actual cartridge. The linked dummy cartridges <NUM> and the first dummy cartridge <NUM> may be linked together using a series of links <NUM> and rollers <NUM>. Each roller <NUM> can include a pin portion that passes through a corresponding link <NUM>, and a head portion having a larger diameter than the pin portion and shaped to interface with and roll along inner sides of a magazine. Each roller <NUM> may pass through a first hole <NUM> in a link <NUM> and into a hole (not visible) in a linked dummy cartridge <NUM> or the first dummy cartridge <NUM>, rotatably coupling the link <NUM> to the linked dummy cartridge <NUM> or the first dummy cartridge <NUM>. Each link <NUM> may have a protruding portion <NUM> with a second hole <NUM> configured to allow a roller <NUM> of the following adjacent linked dummy cartridge <NUM> to pass through, rotatably coupling the link <NUM> of one linked dummy cartridge <NUM> to the following adjacent linked dummy cartridge <NUM>. The second hole <NUM> of the last link <NUM> in the follower assembly <NUM> may have no roller <NUM>. The second hole <NUM> of the link <NUM> of the preceding linked dummy cartridge <NUM>, or first dummy cartridge <NUM>, may be positioned below the first hole <NUM> of the link <NUM> of the current linked dummy cartridge <NUM>; however, in other embodiments, the second hole <NUM> of the link <NUM> of the preceding linked dummy cartridge <NUM>, or first dummy cartridge <NUM>, may be positioned above the first hole <NUM> of the link <NUM> of the current linked dummy cartridge <NUM>. The resulting chain of linked dummy cartridges <NUM> and first dummy cartridge <NUM> allows each adjacent pair of linked dummy cartridges <NUM>, or first dummy cartridge <NUM> and the adjacent linked dummy cartridge <NUM>, to rotatably move about each other. As a consequence, the follower assembly <NUM> may have a high degree of flexibility enabling it to traverse non-linear tracks within a magazine, such as the winding tracks of a drum magazine. Each linked dummy cartridge <NUM>, link <NUM>, and roller <NUM> may combine to form a roughly cartridge-like shape enabling the follower assembly <NUM> to interface with the mechanisms of the magazine, such as the cartridge alignment and cartridge moving mechanisms, which may allow the follower assembly <NUM> to move through the magazine in a fashion similar to an actual stack of cartridges.

In some examples, the follower assembly <NUM> may interface with a mechanism for moving cartridges within the drum magazine body (e.g., drum body <NUM> in <FIG>), such as a follower spring. In one embodiment, the follower spring can be a torsional spring coupled to a rotatable arm. The cartridge-like size and shape of the linked dummy cartridges may enable the follower assembly <NUM> to mimic a cartridge stack and traverse a spiral track (not shown) within the drum body while producing minimal frictional forces and maintaining proper alignment so as to avoid causing blockages or jams. When no cartridges remain in the magazine, the follower assembly <NUM> may extend beyond the end or top of the feed tower (e.g., feed tower <NUM> in <FIG>) to align with and engage a bolt lock-back mechanism. A stop on the follower assembly <NUM> may interface with a surface near the top of the feed tower of the magazine causing a front of the first dummy cartridge of the follower assembly <NUM> to kick up and extend even further beyond the end or top of the feed tower of the magazine and assist in interfacing with and directing force into the slide lock-back interface or mechanism of the firearm. The stop can be arranged toward a rear of the first dummy cartridge from a center of gravity thereof.

Claim 1:
A firearm magazine, comprising:
a body (<NUM>);
a feed tower (<NUM>);
wherein the feed tower (<NUM>) is configured to house one or more cartridges (<NUM>) and comprises:
a feed end,
a base end, and characterised in that the firearm magazine further comprises
one or more leaf springs (<NUM>, <NUM>) positioned within the feed tower (<NUM>) and configured to bias the one or more cartridges (<NUM>) through the feed tower (<NUM>) towards the feed end or the base end of the feed tower (<NUM>),
wherein the one or more leaf springs (<NUM>, <NUM>) are nested opposite each other on a right side and a left side of the one or more cartridges (<NUM>) in the feed tower (<NUM>); and
the body (<NUM>) is coupled to the base end of the feed tower (<NUM>) and is configured to receive the one or more cartridges (<NUM>) from the one or more leaf springs (<NUM>, <NUM>).