Patent Description:
At least one known drum magazine has a bolt catch engagement feature in its feed tower configured to engage a bolt catch in the weapon to lock the bolt in a rearward position after the last cartridge is fired. While functional and reliable in some firearm platforms, such as AR style platforms, this drum magazine is not compatible with others, such as the CZ Scorpion.

Lasichak (<CIT>) discloses a drum magazine having a bolt stop actuator arranged in a vertical channel in a rear of the feed tower that is biased upward when a stop actuator follower contacts a bottom of the bolt stop actuator. However, the stop actuator follower requires a biased plunger that extends into the vertical channel when the stop actuator follower enters the feed tower, and this plunger is liable to jam. The stop actuator follower may also have a tendency to rotate while interfacing with a bottom of the bolt stop actuator, which leads to unnecessary friction between these two components. <CIT> discloses a pistol magazine adapter having a body closely received in the magazine well and defining a passage receiving a magazine including a follower, a bolt catch actuator mechanism having a follower contact element pivotally connected to the body at a pivot axis and having a follower contact surface operable to contact the follower and responsive to whether the follower is in an upper position when the magazine is empty of ammunition or a lower position in which the magazine contains ammunition.

SureFire provides high-capacity magazines utilizing nesting polymer (i.e., multi-piece) followers. Again, however, these magazines are not suited for engaging a bolt catch of a CZ Scorpion-style receiver.

Thus, an alternative bolt catch mechanism is needed for a magazine (e. , a drum magazine, a single stack magazine, or a dual-stack magazine) that is operative with certain firearm platforms, such as the CZ Scorpion.

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.

Some embodiments of the disclosure may be characterized as a magazine comprising a feed tower or an elongated casing having at least a distal end and a proximal end, and two sides longer than the distal and proximal ends. The magazine may further comprise a follower having a tab extending toward one of the two sides (or toward the distal end or toward the proximal end) and a bolt catch mechanism arranged at least partially inside and near a top of the elongated casing or feed tower, wherein the tab is arranged to contact and bias upward the bolt catch mechanism into a position configured to engage a bolt catch of a firearm that the magazine is engaged with. Although not shown, where the tab extends toward the distal or proximal end of the feed tower or elongated casing, the tab may interface with a bolt lock mechanism also arranged on the same distal or proximal end of the follower. Alternatively, the bolt lock mechanism could still comprise an arm running along one side of the follower, but further including a flange that wraps around from the side to the distal or proximal end of the follower so as to interface with the proximally or distally extending tab. This variation on the bolt lock mechanism can also pivot or slide vertically.

In some embodiments, the bolt catch mechanism is pivotable around a pivot axis toward the distal end of the elongated casing or feed tower. In some embodiments, the pivot axis is arranged in an opening in the distal end of the elongated casing or feed tower. In some embodiments, a bolt-engagement portion of the bolt catch mechanism protrudes through an opening in the proximal end of the elongated casing or feed tower.

In some other embodiments, a bolt-engagement portion of the bolt catch mechanism protrudes through an opening in the proximal end of the elongated casing or feed tower.

In some embodiments, the bolt catch mechanism is slidable along a path parallel with the follower once the tab contacts a lower surface of the bolt catch mechanism. In some embodiments, the tab is arranged toward the proximal end of the elongated casing or feed tower.

In some embodiments, the follower comprises a plurality of dummy cartridges coupled via movable links, and wherein the tab extends from one of the movable links or one of the plurality of dummy cartridges. In some embodiments, the bolt catch mechanism is an arm extending from the proximal end to the distal end of the elongated casing or feed tower.

In some embodiments, the tab contacts the bolt catch mechanism toward the proximal end of the elongated casing or feed tower. In some embodiments, the magazine is a single stack, double stack, or drum magazine. In additional embodiments, the magazine is a drum magazine and the drum magazine includes a drum coupled to a bottom of the feed tower, and wherein the drum has a constant internal curve that causes axes of cartridges in the drum to intersect in front of the drum. In some embodiments, the drum and feed tower share a constant internal curve.

In some embodiments, the casing or feed tower is shaped to hold a single stack of cartridges from a bottom of the casing or feed tower toward a top of the casing or feed tower, and to transition to a double stack at the magazine's interface to the firearm.

Other embodiments of the disclosure may also be characterized as method of manufacturing a magazine, wherein the method comprises providing an elongated casing or feed tower having at least a distal end and a proximal end, and two sides longer than the distal and proximal ends, providing a follower having a tab, arranging the follower in the magazine such that when the follower moves within the elongated casing or feed tower, the tab extends toward one of the two sides, arranging a bolt catch mechanism within an upper portion of the elongated casing or feed tower such that the tab is arranged to contact the bolt catch mechanism and push it upward when the follower approaches or reaches a top of the magazine. In some embodiments, the bolt catch mechanism is configured to engage a bolt catch of a firearm that the magazine is engaged with when the follower approaches or reaches the top of the magazine.

In some embodiments, the method further comprises pivotally coupling the bolt catch mechanism to the elongated casing or feed tower at a pivot axis. In some additional embodiments, the method comprises forming a distal opening in the casing or feed tower and pivotally coupling the bolt catch mechanism to the elongated casing or feed tower within the distal opening. In some additional embodiments, the method comprises coupling the bolt catch mechanism to the elongated casing or feed tower via a sliding engagement.

In some embodiments, the method further comprises forming a bolt catch mechanism recess in one of the two sides and arranging the bolt catch mechanism within this recess. In some additional embodiments, the method further comprises forming a proximal opening in the proximal end of the elongated casing or feed tower, and arranging a bolt-engagement portion of the bolt catch mechanism within the proximal opening.

Other embodiments of the disclosure can be characterized as a magazine with a bolt catch mechanism. The magazine can have at least a distal end and a proximal end and two sides. The magazine can include an elongated casing or feed tower, a follower, and the bolt catch mechanism. The follower can have a tab extending toward one of the two sides (or toward the distal end or toward the proximal end), a side on which the bolt catch mechanism is arranged. The bolt catch mechanism can be pivotable or slidably, or have some other form of movement, as long as it is able to contact and push upward on the firearm's bolt catch when a final round of the magazine exits the magazine. The bolt catch mechanism can be at least partially inside and near a top of the elongated casing or feed tower. The bolt catch mechanism, if pivotable, can have a pivot axis toward the distal end of the elongated casing or feed tower. The tab can be arranged on the follower to contact the bolt catch mechanism, for instance, toward the proximal end of the elongated casing or feed tower where the bolt catch mechanism is pivotable. In fact, the tab can be arranged on the follower to contact the bolt catch mechanism anywhere along its length proximal to the pivot axis, if applicable. This arrangement allows the tab to push upward on the bolt catch mechanism when the follower approaches an uppermost position in the elongated casing or feed tower (e.g., the magazine approaches or reaches an empty state) and into a position to engage the bolt catch of the firearm. This may involve a pivoting or sliding motion.

An alternate embodiment of the disclosure may be characterized as a drum magazine comprising a drum, a feed tower having a front corner aperture near a top of the feed tower and a rear corner aperture near the top of the feed tower, and a follower assembly configured to follow a spiral path through the drum and a roughly linear path through the feed tower. The follower assembly may comprise a pivotable bolt catch mechanism having a pivot coupling coupled to the feed tower within the front corner aperture and having an engaged and disengaged position, wherein in the engaged position an end of the mechanism opposite from the pivot coupling extends through the rear corner aperture and wherein in disengaged position the end of the mechanism does not extend through the rear corner aperture. The follower assembly may further comprise two or more dummy cartridges and two or more links, one surrounding at least a portion of each dummy cartridge. In other words, at least a portion of each dummy cartridge is surrounded by at least one link. In some embodiments, a tab extends roughly sideways from at least one of the links or dummy cartridges such that when the two or more dummy cartridges move to a top of the feed tower, the tab biases the pivotable bolt catch mechanism upward into the engaged position.

Another embodiment of the disclosure may be characterized as a method of engaging a bolt catch in a firearm, wherein the method comprises presenting a final cartridge from a magazine into a chamber of the firearm via upward movement of a follower in an elongated casing or feed tower of a magazine, contacting a lower surface of a bolt catch mechanism of the magazine with a tab extending sideways from the follower (or toward the distal end or toward the proximal end), forcing the bolt catch mechanism upwards into an engaged position, and securing the bolt catch in a locked position with a bolt-engagement portion of the bolt catch mechanism as a result of upward movement of the bolt catch mechanism. In some embodiments, the bolt catch mechanism pivots upward to secure the bolt catch in the locked-back position.

These and other features, and characteristics of the present technology, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. As used in the specification and in the claims, the singular form of 'a', 'an', and 'the' include plural referents unless the context clearly dictates otherwise.

Various objects and advantages and a more complete understanding of the present disclosure are apparent and more readily appreciated by referring to the following detailed description and to the appended claims when taken in conjunction with the accompanying drawings:.

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.

The present disclosure relates generally to a novel bolt catch mechanism for a magazine that is operative with a CZ scorpion-type receiver (e.g., a drum magazine, a single stack box magazine, or a dual-stack box magazine). More specifically, this disclosure describes a magazine having a feed tower (also spelled as feed tower) or elongated casing with a pivoting bolt lock back arm (also referred to as arm) that can be biased upward around a pivot axis by a tab on a follower as the follower nears or reaches a top of the magazine. In some cases, the pivoting bolt lock back arm may not pivot, but instead slide in a direction roughly parallel to a path of the follower.

In some other embodiments, the follower may not include a tab, and instead the pivoting bolt lock back arm may comprise a tab or a jog that is aimed back (i.e., sideways) toward the follower. In such cases, this tab or jog may be pushed upward by the follower, rather than a tab on the follower pushing the arm up. In either arrangement, the pivoting bolt lock back arm may engage the bolt catch of the firearm when the follower approaches an uppermost position in the elongated casing or feed tower (e.g., the magazine approaches or reaches an empty state).

<FIG> illustrates a left side elevation view of an embodiment of a feed tower <NUM> of a magazine having a unique bolt catch mechanism. In some examples, the magazine may be a single stack or double stack box magazine. In other cases, the magazine may be a drum magazine assembly, as further described in relation to <FIG>. In all three of these variations, the magazine may include a constant internal curve that causes cartridges or rounds in the drum to intersect in front of the drum, as described in <FIG>. In some circumstances, the drum and feed tower may share a constant internal curve. That is, the focal points of cartridges throughout the drum and feed tower may have focal points that intersect at a substantially single point in front of the magazine. However, in another embodiment, the feed tower and drum may have different focal points, for instance, where a focal point of cartridges in the feed tower is lower than a focal point of cartridges in the drum. In this case, both the feed tower and the drum may have constant internal curves, and those curves may be the same or different radii.

Irrespective of the exact type of magazine, the magazine may comprise an elongated casing or feed tower having at least a distal end and a proximal end, and two sides longer than the distal and proximal ends. Furthermore, the magazine may comprise a follower having a tab extending towards one of the two sides, and a bolt catch mechanism arranged at least partially inside and near a top of the elongated casing or feed tower. The tab may be arranged to contact and bias upward the bolt catch mechanism into a position configured to engage a bolt catch of a firearm that the magazine is engaged with, as further discussed below. In the example of <FIG>, the tab contacts the bolt catch mechanism towards the proximal end (rear) of the elongated casing or feed tower. Variations where the tab contacts the bolt catch mechanism towards the distal end of the feed tower are also discussed later in the disclosure.

<FIG> show the bolt catch mechanism in the engaged and disengaged positions, respectively. As shown, <FIG> depict a bolt catch mechanism <NUM>, a pivot coupling <NUM>, an aperture <NUM>, an aperture <NUM>, and a topmost (or last) cartridge <NUM>. In some examples, the bolt catch mechanism <NUM> can pivot around a pivot axis (i.e., passing through the pivot coupling <NUM>). In the example of <FIG>, the pivot axis is arranged in an opening or aperture in the distal end (front end) of the elongated casing or feed tower. Further, to make room for the bolt catch mechanism <NUM> while not extending outside the boundaries of the feed tower <NUM>, an opening (i.e., aperture <NUM>) in the front corner of the feed tower <NUM> may be formed to make room for the pivot coupling <NUM>. Additionally or alternatively, another opening (i.e., aperture <NUM>) in a rear corner/proximal end of the feed tower <NUM> may be formed to allow a rear end of the bolt catch mechanism <NUM> to extend outside the feed tower <NUM> and interface with a bolt, or intermediate bolt catch, of a firearm when the bolt catch mechanism <NUM> is in the engaged position. In some cases, these apertures are not needed, and the bolt catch mechanism <NUM> can reside entirely within the feed tower <NUM>.

<FIG> illustrates cross section views of <FIG>. Specifically, <FIG> illustrates a cross section of <FIG> (i.e., engaged position) and <FIG> illustrates a cross section of <FIG> (i.e., disengaged position). As shown in <FIG>, the feed tower may comprise a bolt catch mechanism <NUM>, a pivot coupling <NUM>, apertures <NUM> and <NUM>, one or more ridges <NUM>, a dummy round <NUM> (one of a plurality that make up the follower), and a tab <NUM>. In some examples, the bolt catch mechanism <NUM> may comprise a pivoting bolt lock back arm and a bolt-engagement portion <NUM>. In this example, the pivoting lock back arm may extend from the proximal end to the distal end of the elongated casing or feed tower. As discussed above, the tab <NUM> may be located on the follower within the feed tower of the magazine. Alternatively, the tab <NUM> may be part of or affixed to one of the links in a chain of dummy rounds (e.g., dummy round <NUM>), as further described in relation to <FIG>. In some cases, the dummy rounds may also be referred to as follower dummies.

<FIG> depicts the bolt catch mechanism <NUM> biased towards the disengaged position via a spring or other biasing mechanism, as further described in relation to <FIG> and <FIG>. For instance, <FIG> illustrates a perspective view of an embodiment of bolt catch mechanism <NUM> and follower with tab <NUM> in isolation, where the bolt catch mechanism <NUM> may be biased towards the disengaged position via a spring <NUM>.

As long as final round <NUM> has not left the feed tower <NUM>, there is no force to oppose the bias of the spring and the bolt catch mechanism <NUM> remains in the disengaged position. Specifically, when the tab <NUM> is not biasing the bolt catch mechanism <NUM> upward, the spring bias pushes the bolt catch mechanism <NUM> downward, but rotation downward is halted by contact with top edges of two ridges <NUM> extending inward from the inside of the feed tower <NUM> on the same side of the feed tower <NUM> as the bolt catch mechanism <NUM> (or extending toward the distal end or extending toward the proximal end).

In some cases, the casing or feed tower may be shaped to hold a single stack of cartridges from a bottom of the casing or feed tower towards a top of the casing or feed tower, and to transition to a double stack at the magazine's interface to the firearm (e.g., at a top of the magazine). In some embodiments, the ridges <NUM> (also referred to as ribs) under the bolt catch mechanism may also serve to guide single stack rounds or cartridges until they approach or clear the pivoting lock back arm. Once cartridges approach or clear the arm they may be pushed into the double stacked portion of the feed tower. That is, while the cartridges are generally stacked in a singular fashion within the feed tower, they may be in a double stack configuration at the action/receiver of the firearm.

Turning now to <FIG>, when the final round <NUM> leaves the feed tower <NUM>, the pivoting bolt lock back arm of the bolt catch mechanism <NUM> may be biased upward around the pivot coupling <NUM> by the tab <NUM> on the follower as the follower nears or reaches a top of the magazine. In some examples, the tab <NUM> impinges on a bottom of the bolt catch mechanism <NUM>. The force of this impingement is greater than the bias from the spring and so the bolt catch mechanism <NUM> is rotated (or pushed) upward such that an end (e.g., bolt engagement portion <NUM>) of the bolt catch mechanism <NUM> extends out of the aperture <NUM> in the back corner of the feed tower <NUM>.

<FIG> shows a perspective view of the cross section of <FIG>. As shown, <FIG> illustrates a tab <NUM> that is part of or affixed to one of the links in a chain of dummy rounds, such as dummy round <NUM>. In some examples, when a final round leaves the feed tower and is replaced by the first dummy round <NUM>, the pivoting bolt lock back arm of the bolt catch mechanism <NUM> may be biased upward around the pivot coupling <NUM> by the tab <NUM> on the follower (i.e., as the follower nears or reaches a top of the magazine). Specifically, the follower may comprise a plurality of dummy cartridges coupled via movable links, and the tab <NUM> may extend from one of the movable links or one of the plurality of dummy cartridges of the follower. As the tab <NUM> moves upward, it impinges on a bottom of the bolt catch mechanism <NUM>. The force of this impingement may cause the bolt catch mechanism <NUM> to rotate (or slide) upward such that the bolt-engagement portion <NUM> of the bolt catch mechanism protrudes through the aperture <NUM> in the back corner of the feed tower <NUM>.

It should be noted that, while a drum magazine and its feed tower are discussed and shown herein, in other embodiments, the bolt catch mechanism <NUM> can be applied to single or double stack box-type magazines rather than a drum magazine. In those cases, the tab <NUM> can extend from a traditional follower. Also, since a typical magazine uses a double stack, embodiments of this disclosure can use a single stack box-type magazine, or single-stack feed tower for a drum, but use a casing or feed tower width closer to that of a double stack, thereby making more room for the bolt catch mechanism <NUM> within the magazine or feed tower and next to a single stack portion of the casing or feed tower. In some cases, box-type magazines (e.g., single stack or double stack) may comprise a follower and a follower spring, where at least a portion of the follower spring is fixed to or coupled to the follower. In such cases, the tab <NUM> may be situated on the follower spring in the box magazine.

<FIG> illustrates a perspective view of the follower with tab <NUM> of <FIG> in isolation. Further, <FIG> illustrates an embodiment of an exploded view of a portion of a follower for a drum magazine including two dummy rounds <NUM> and <NUM>, two links <NUM> and <NUM>, two follower dummy rollers <NUM> and <NUM>, and the tab <NUM>. Although the tab <NUM> is shown as part of the first link <NUM> throughout this disclosure, the tab <NUM> could also be part of or attached to the second <NUM> or third link (or any subsequent dummy round or link) in the chain of dummy rounds of the follower assembly, or a dummy cartridge. In some embodiments, the dummy cartridge that has the tab <NUM> may not be rotatable. For ease of reference, the term dummy cartridge (e.g., dummy cartridges <NUM> and <NUM> in <FIG>) may be used in this disclosure to reference a combination of a follower dummy roller (e.g., follower dummy roller <NUM>) and a follower dummy or dummy round (e.g., dummy round <NUM>). The terms first dummy cartridge <NUM> or leading dummy cartridge <NUM> may be used to reference the combination of the leading follower dummy roller <NUM> and the leading follower dummy <NUM>.

In some embodiments, the follower assembly may have an inner spindle slider (e.g., see inner spindle slider <NUM> in <FIG>), an outer spindle slider (e.g., see outer spindle slider <NUM> in <FIG>), a spindle (e.g., see spindle <NUM> in <FIG>), a plurality of follower dummy rollers <NUM> and <NUM> (see <FIG>), a plurality of follower dummies <NUM> and <NUM>, where follower dummy roller <NUM> is the leading follower dummy roller <NUM>, and dummy <NUM> is the leading follower dummy. The follower assembly may also comprise a plurality of follower links <NUM> and <NUM>, also referred to as links <NUM> and <NUM> for short.

In some embodiments, one or more of the follower dummy rollers <NUM> may rotate relative to the respective follower dummies <NUM>, which may also rotate relative to the spiral track (not shown). That is, a front portion of a dummy cartridge <NUM> may rotate relative to a rear portion of a dummy cartridge <NUM>. Similarly, a front portion of a leading dummy cartridge <NUM> may rotate relative to a rear portion of a leading dummy cartridge <NUM>. Allowing the front and rear portions of dummy cartridges <NUM>, <NUM> to rotate relative to each other as they pass through the spiral track may serve to minimize the frictional forces between the follower assembly and the drum body assembly.

In the present disclosure, the plurality of dummy cartridges <NUM>, <NUM> are linked by a plurality of links <NUM>, <NUM>, such that each dummy cartridge <NUM>, <NUM> is allowed to rotate within each link <NUM>, <NUM> independently of the other dummy cartridges <NUM>, <NUM> and the first dummy cartridge <NUM>. This independent rolling may serve to substantially reduce the amount of sliding friction as the dummy cartridges of the follower assembly wind through the spiral track.

In order to achieve this independent rotation and minimize sliding friction, all or a majority of the spring force may be carried by the stacked follower links <NUM>, <NUM> in a kinetic chain, thus allowing for independent rotation of the dummy cartridges <NUM>, <NUM>. It should be noted, however, that it is not a requirement that the entire first dummy cartridge <NUM> not rotate.

<FIG> also provides two views of the feed tower <NUM> with the bolt catch mechanism <NUM> in the engaged (bottom right) and disengaged (top right) positions. As shown, in the disengaged position, the aperture <NUM> in the feed tower <NUM> may be clearly seen without the bolt-engagement portion <NUM> of the bolt catch mechanism. However, in the engaged position, the tab <NUM> (not shown) may cause the bolt catch mechanism <NUM> to rotate upward such that the bolt-engagement portion <NUM> of the bolt catch mechanism protrudes through the aperture <NUM> in the back corner of the feed tower <NUM>.

<FIG> illustrate two isolated perspective views of one embodiment of the bolt catch mechanism <NUM>.

<FIG> illustrates a cross section of two states (i.e., disengaged position on left, engaged position on right) of an embodiment of a firearm system including a magazine <NUM> with a feed tower, a bolt catch mechanism <NUM> comprising a pivoting bolt lock back arm and bolt engagement portion, a bolt catch <NUM>, and a bolt <NUM>. In some examples, the system depicted in <FIG> may implement one or more aspects of <FIG>. For instance, the bolt catch mechanism portion <NUM> may be similar or substantially similar to the bolt catch mechanism <NUM> shown in the figures above. In some examples, the magazine's feed tower may also comprise a pivot coupling <NUM> (similar to the pivot coupling <NUM> above), one or more apertures (e.g., front and rear of feed tower), one or more ridges, and a tab <NUM> (similar to the tab <NUM> above). As previously described, the bolt catch mechanism may pivot around the pivot coupling <NUM> in the feed tower. In some circumstances, apertures in the front and rear corners of the feed tower may be formed to make room for the pivot coupling <NUM> and the bolt engagement portion of the bolt catch mechanism, respectively.

Moving to the engaged position, the tab <NUM> on the follower may bias the pivoting bolt lock back arm of the bolt catch mechanism <NUM> upward pivoting around the pivot coupling <NUM> by the tab <NUM> on the follower (i.e., as the follower nears or reaches a top of the magazine <NUM>). As the tab <NUM> moves upward, it impinges on a bottom of the bolt catch mechanism <NUM>. The force of this impingement may cause the bolt catch mechanism <NUM> to rotate upward such that the bolt-engagement portion of the bolt catch mechanism <NUM> protrudes through the aperture in the back corner of the feed tower <NUM>. The upward movement of the bolt catch mechanism <NUM> may cause the bolt catch <NUM> of the firearm to be secured in a locked position. In some cases, when pushed upward by the follower of an empty magazine, the bolt catch <NUM> may function to stop bolt <NUM> from traveling forward (i.e., to the left in <FIG>). In such cases, the bolt <NUM> may be locked to the rear after the magazine <NUM> has been expended. After inserting a new magazine in the firearm, the bolt catch mechanism may return to the disengaged position (i.e., default unlocked position), either automatically or by the user.

<FIG> illustrates a cross section of two states (i.e., disengaged position on left, engaged position on right) of a second embodiment of a firearm system including a magazine <NUM> with a feed tower, a bolt catch mechanism <NUM> with a bolt engagement portion, a bolt catch <NUM>, and a bolt <NUM>. Unlike the firearm system shown in <FIG>, the system of <FIG> may not comprise a pivot coupling point. However, the magazine's feed tower may comprise one or more apertures (e.g., front and rear of feed tower), one or more ridges, and a tab <NUM> (similar to the tab <NUM> above). In some cases, after the last round in the magazine <NUM> has been expended, the tab <NUM> on the follower may move upward and collide with (or engage with) the bolt catch mechanism <NUM>. In such cases, the upward movement of the tab <NUM> may cause the bolt catch mechanism <NUM> to also move upward and engage with the bolt catch <NUM> of the firearm, which may cause the bolt catch <NUM> to be engaged in a locked position. In the engaged position, the bolt catch <NUM> may prevent the bolt <NUM> from traveling forward by locking the bolt <NUM> to the rear.

<FIG> illustrates a cross section of two states (i.e., disengaged position on left, engaged position on right) of a third embodiment of a firearm system including a magazine <NUM> with a feed tower, a bolt catch mechanism <NUM> with a pivoting bolt lock back arm and a bolt engagement portion, a bolt catch <NUM>, and a bolt <NUM>. In some firearm systems (e.g., Glocks, pistols, etc.), the bolt catch <NUM> may be situated towards the distal end (i.e., front or barrel end of the firearm). In such cases, pivot coupling point <NUM> may be located towards the proximal end (i.e., rear end) of the firearm. In some embodiments, the bolt catch mechanism <NUM> may be similar or substantially similar to the bolt catch mechanism <NUM> or bolt catch mechanism <NUM> described above, where the bolt catch mechanism <NUM> pivots around the pivot coupling <NUM> in the feed tower. In some examples, the magazine <NUM>'s feed tower may also comprise one or more apertures (i.e., front and/or rear of feed tower), one or more ridges, and a tab <NUM> (similar to the tab <NUM> or tab <NUM> above).

As shown, in the engaged position (i.e., after a last round or cartridge has been fired), the tab <NUM> moves upward and causes the bolt catch mechanism <NUM> to pivot around the pivot coupling point <NUM> in the feed tower. In such cases, the upward movement of the bolt catch mechanism <NUM> may secure the bolt catch <NUM> of the firearm in a locked position. In this position, the bolt catch <NUM> may lock the bolt <NUM> and stop it from traveling forward (i.e., to the left in <FIG>) in the firearm.

While <FIG> shows a bolt (<NUM>), in other embodiments, the bolt <NUM> could be replaced by a slide having a slide lock (e.g., in a GLOCK). In that case, the bolt catch <NUM> may move up and into the way of forward movement of the slide lock. Further, while the bolt catch <NUM> has been shown as a single component, in other embodiments, the bolt catch <NUM> can be formed from multiple components or multiple interlinked components, such as the interlinking between the GLOCK slide release and the slide. Further, while the illustrations show a bolt catch <NUM> having a tab projecting rearward (to the right of the page), in other embodiments, the bolt catch <NUM> could have a tab extending inward (e.g., into the page) and the bolt catch <NUM> may overlap a portion of the bolt catch mechanism <NUM> (when viewed from the side as in <FIG>). What is more, the bolt catch <NUM> has been shown as moving linearly up and down, but in other embodiments, could also include a rotating or pivoting motion, such as that seen in the GLOCK platform. Further, while the bolt <NUM> is a simplified representation of a typical bolt, bolts come in a variety of shapes and sizes, and thus the shape shown as <NUM> should not be limiting. For instance, in a GLOCK-style platform, a slide rather than a bolt may be implemented.

<FIG> illustrates a cross section of two states (i.e., disengaged position on left, engaged position on right) of a fourth embodiment of a firearm system including a magazine <NUM> with a feed tower, a bolt catch mechanism <NUM> with a bolt engagement portion, a bolt catch <NUM>, and a bolt <NUM>. In some aspects, the firearm system of <FIG> may be similar to the firearm system shown in <FIG>, with the primary difference being the location of tab <NUM>. In some examples, the firearm system of <FIG> may also comprise one or more apertures (e.g., front and rear of feed tower) and/or one or more ridges (not shown). In some cases, after the last round in the magazine <NUM> has been expended, the tab <NUM> on the follower may move upward and collide with (or engage with) the bolt catch mechanism <NUM>. In such cases, the upward movement of the tab <NUM> may cause the bolt catch mechanism <NUM> to also move upward and engage with the bolt catch <NUM> of the firearm, thus engaging the bolt catch <NUM> in a locked position. In the engaged position, the bolt catch <NUM> may prevent the bolt <NUM> from traveling forward (i.e., to the left in <FIG>) in the firearm, which may allow for faster reloading.

While <FIG> shows a bolt (<NUM>), in other embodiments, the bolt <NUM> could be replaced by a slide having a slide lock (e.g., in a GLOCK). In that case, the bolt catch <NUM> may move up and into the way of forward movement of the slide lock. Further, while the bolt catch <NUM> has been shown as a single component, in other embodiments, the bolt catch <NUM> can be formed from multiple components or multiple interlinked components, such as the interlinking between the GLOCK slide release and the slide. Further, while the illustrations show a bolt catch <NUM> having a tab projecting rearward (to the right of the page), in other embodiments, the bolt catch <NUM> could have a tab extending inward (e.g., into the page) and the bolt catch <NUM> may overlap a portion of the bolt catch mechanism <NUM> (when viewed from the side as in <FIG>). Further, while the bolt <NUM> is a simplified representation of a typical bolt, bolts come in a variety of shapes and sizes, and thus the shape shown as <NUM> should not be limiting. For instance, in a GLOCK-style platform, a slide rather than a bolt may be implemented.

The illustrated bolts, <NUM>, <NUM>, <NUM>, and <NUM> are shown with a wider diameter flange or teeth at a front of the bolt, much like one would see in an AR-style bolt. However, those of skill in the art will appreciate, that this is just one implementation of a bolt, and this disclosure can easily be applied to other shapes and variations of a bolt, such as that seen in a CZ Scorpion platform (where the bolt is more of a rectangular block rather than including a flange or teeth at a front end). In other embodiments, and as described above, the bolt can be replaced by a slide (e.g., in a Glock-style platform). These and other changes to the shape of the bolt or slide do not influence the magazine construction or operation of the magazine beyond the descriptions and figures provided herein.

Additionally, while the illustrated bolt catches <NUM>, <NUM>, <NUM>, and <NUM> are shown moving in a linear fashion between a disengaged and engaged position, in other embodiments, the bolt catch <NUM>, <NUM>, <NUM>, and <NUM> may pivot when moving between these two positions.

<FIG> illustrate views of an alternate embodiment of a feed tower where the follower tab is located at a proximal end of the feed tower, and where the bolt catch mechanism of the magazine also pivots at the proximal end of the feed tower, as further described below. In some cases, the unique geometry of the pivoting bolt lock back arm of the bolt catch mechanism may allow it to be engaged in spite of a shorter distance (i.e., as compared to <FIG> above) between the pivot coupling point and the point at which the engagement force is applied. For instance, unlike the bolt catch mechanism depicted in <FIG>, <FIG>, <FIG>, <FIG>, or <FIG>, where the pivoting bolt lock back arm is relatively straight or horizontal, the bolt catch mechanism illustrated in <FIG> has a substantially irregular or curved lower portion. Because of this, the tab can impinge on a proximal end of the bolt catch mechanism while still causing the bolt catch mechanism to pivot around a proximal end of the bolt catch mechanism.

For instance, once the tab contacts a lower surface of the bolt catch mechanism or slides under the bolt catch mechanism, the bolt catch mechanism may be pivoted upward. In other words, an upward motion of the tab under the curved lower portion of the bolt catch mechanism may lead to a sliding motion of the bolt catch mechanism, where the sliding motion is parallel with the follower. Further, the unique geometry of the bolt catch mechanism in conjunction with the sliding motion may swing its opposite narrower end (e.g., see <FIG>, <FIG>, and <FIG>) upward into an engaged position. In some cases, this mechanism may also be referred to as a pivoting slide stop or pivoting slide catch mechanism.

<FIG> illustrates a perspective view of an alternate embodiment of a feed tower <NUM> having a bolt catch mechanism <NUM> that pivots at a proximal end of the feed tower <NUM> via pivot <NUM>. <FIG> illustrates another perspective view of the embodiment shown in <FIG> with the pivot <NUM>, the bolt catch mechanism <NUM>, and a bias spring <NUM>. The spring <NUM> can be arranged at a radius from the pivot <NUM>, and the spring <NUM> can push up against a flange above the spring <NUM> as shown in <FIG> and <FIG>. In some examples, the bolt lock back arm of the bolt catch mechanism <NUM> may be biased towards the disengaged position via the bias spring <NUM>. The illustrated bias spring <NUM> extends from a wall, but in practice could end flush with that wall. <FIG> illustrates a cutaway view of an inside of the embodiment shown in <FIG> with the spring <NUM> and the pivot <NUM>.

<FIG> illustrates a head on view of the bolt catch mechanism <NUM> and a tab <NUM> of the follower corresponding to the embodiment shown in <FIG>. Further, <FIG> illustrates a profile view of the bolt catch mechanism <NUM> and follower with tab <NUM> shown in <FIG>. Lastly, <FIG> illustrates a perspective view of the bolt catch mechanism <NUM> and follower with tab <NUM> shown in <FIG>.

In some circumstances, the design of the firearm may require a pivot mechanism (i.e., pivot <NUM> in <FIG>) at a proximal end of the feed tower, for instance, due to the arrangement and/or location of the bolt (not shown). In such cases, one or more dummy cartridges <NUM> may be deployed in the follower assembly of the magazine, where each of the dummy cartridges may comprise at least a dummy round, a link <NUM>, and optionally a tab <NUM>. In some examples, link <NUM> may surround at least a portion of dummy cartridge <NUM> (shown in <FIG>, but not in <FIG>).

In some cases, at least one of the dummy cartridges may be a first or leading dummy cartridge, as previously discussed in relation to <FIG>. Further, the tab <NUM> may be a part of or attached to any of the dummy cartridges <NUM>, such as the first or leading dummy cartridge, a second to last dummy cartridge, or another dummy cartridge. Additionally or alternatively, the tab <NUM> may be attached to any dummy round or link in the chain of dummy rounds or links of the follower assembly. In the example shown in <FIG>, tab <NUM> is attached to link <NUM>.

In some cases, when the dummy cartridge <NUM> moves to a top of the feed tower, the tab <NUM> may bias the pivotable bolt catch mechanism <NUM> upward into the engaged position, securing the bolt catch (not shown) of the firearm in a locked position with a bolt-engagement portion of the bolt catch mechanism <NUM>.

<FIG> and <FIG> illustrate an exploded view and a perspective view, respectively, of a drum magazine assembly <NUM>. In some cases, the drum magazine assembly <NUM> may comprise a front cover assembly <NUM>, a wheel <NUM>, a drum body and spring assembly <NUM>, a follower assembly <NUM>, a rear cover <NUM>, and retainer clips <NUM>. In some examples, a feed tower assembly <NUM> may be coupled to a drum body <NUM> and retained by the front cover <NUM>. The feed tower assembly may implement aspects of the feed tower described in reference to <FIG> and <FIG> above. In some cases, wheel <NUM> may comprise one or more teeth <NUM> at a distal region of the wheel, and more specifically, at the distal face.

A rear cover <NUM> may be connected to the drum body assembly <NUM> and retained thereon by retaining clips <NUM>. In some embodiments, the drum magazine assembly <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>. It should also be understood that the maximum loading capacity of the drum magazine assembly <NUM> is dependent on the caliber of ammunition used. For larger sized cartridges, for example, and without limitation, the drum magazine assembly <NUM> may be configured to hold as little as <NUM> cartridges at maximum loading capacity. In still other embodiments, the drum magazine assembly <NUM> may be configured to hold as little as <NUM> cartridges at maximum loading capacity. These capacities should be considered exemplary only. In some examples, the drum magazine <NUM> may have a viewing window on the rear cover <NUM>, with the viewing window extending substantially from a central portion of the rear cover <NUM> to a distal portion of the rear cover <NUM>. In some embodiments, the viewing window need not necessarily include a transparent cover; instead, the viewing window may comprise an elongated opening in the rear cover <NUM>, or a series of openings which may or may not be covered with a transparent material and/or semi-transparent material. As another example, the rear cover <NUM> may be manufactured of a transparent or semi-transparent material.

The various components of the drum magazine assembly <NUM> may be manufactured of suitable polymeric materials, high-strength synthetic materials, composites, ceramics, various metals including aluminum, stainless steel or alloys, or any other material suitable for the intended use with a firearm, and the components may have one or more surface finishes suitable to minimizing friction between certain moving parts.

Turning now to <FIG>, it can be seen that the drum magazine assembly <NUM> includes a drum coupled to a bottom of the feed tower. Further, the drum has a constant internal curve that causes axes of cartridges in the drum to intersect in front of the drum. In other words, the drum magazine assembly <NUM> may be designed such that a focal point of each cartridge substantially converges at a single point P at a distance D from the drum magazine assembly <NUM>. Furthermore, and as illustrated in <FIG>, the drum and feed tower may also share a constant internal curve. In some cases, the focal point of the feed tower may be lower than the focal point of the drum. In other words, the focal point of cartridges in the feed tower could be below single point P in <FIG>. In other embodiments the feed tower and the drum can have constant internal curves therein, but constant curves having two different radii, or two different focal points but the same radii.

A continuous curvature between the drum body and the feed tower may be ideal, and many magazine designs according to this disclosure may start with such a constant internal curve. However, if there are cartridge feeding issues, then the cartridge behavior in the feed tower can be altered by angling the feed tower relative to the drum. For instance, angling the feed tower down relative to the drum increasing nose pressure on the cartridges, while angling the feed tower up relieves pressure on the cartridge noses and increases it on rears.

Non-optimal magazines allow cartridges at the Feed Lips to pitch up or down affecting how reliably the weapon can strip the rounds from the magazine and feed it into the chamber. If the bullet pitches up due to lack of pressure on the rear of the round stack, the weapon bolt may not effectively contact the cartridge case head and cause a "bolt over base" malfunction. If the bullet pitches down (nose dives) due to lack of pressure on the front of the round stack, rounds may hit too low on the weapon feed ramp or even impact the front of the magazine affecting smooth cartridge feeding.

Increasing spring pressure can help with the above issues but often magazines will exhibit pitch problems that cannot be fixed through spring pressure alone. To address this issue, pressure on the front or rear of the round stack can be adjusted by increasing or decreasing the pitch of the Drum body itself in relation to the Feed Tower. For instance, pitching the drum section up effectively raises the focal point of the cartridges in the drum and applies additional pressure on the front of the round stack. Pitching the drum section down has the opposite effect and increases the pressure on the rear of the stack.

Another possibility to adjust front or rear stack pressure is to increase or decrease the focal point radius. Shortening the radius compels the cartridges to apply more force on the front of the stack while elongating the radius applies more force to the rear of the stack.

For the purpose of this disclosure, substantial convergence should be understood to mean bringing the convergence within reasonable manufacturing tolerances. This substantial convergence allows for more optimal stacking of the cartridges, thus distributing forces across each cartridge case, and improving stack consistency and feeding. Moreover, the substantial convergence allows the cartridges to pass more smoothly through the drum magazine assembly <NUM> to the loading chamber as compared to a drum assembly not having the substantially converging focal point. It should be noted that the point P is defined by the conical apex of the multiple cartridges, or the length of taper of each cartridge case; that is, the distance D would be greater for cartridges designed with a slight taper than for cartridges designed with a more extreme taper. Also shown in <FIG> and <FIG> is a first pivot axis A of an embodiment, as will be more apparent with brief reference to <FIG> and <FIG>, axis A is approximately defined by the spindle <NUM> of the follower assembly <NUM> in <FIG>. The wheel <NUM> and arm <NUM> in <FIG> may also be configured to pivot about axis A.

Turning now to <FIG>, the front cover assembly <NUM> is now discussed. The front cover assembly <NUM> may have a front cover <NUM>, a lever <NUM>, an arm <NUM>, and a pawl <NUM>. In some circumstances, a return spring <NUM> may also be included in the front cover assembly <NUM>. The front cover assembly <NUM> may provide several functions. First, the front cover <NUM> may provide the wheel <NUM> and the interface between the wheel and other moving components some protection from excessive impacts or other rough handling while in use. The front cover assembly <NUM> including an advancing mechanism or arm <NUM> and lever <NUM> assembly may also provide for an increased moment arm for the user, as compared to turning the wheel <NUM> without the front cover assembly <NUM>. However, it should be understood that the drum magazine assembly <NUM> is a fully functional assembly even when the front cover assembly <NUM> is not present; that is, a user could turn the wheel <NUM> by hand to insert cartridges.

Nonetheless, the front cover assembly <NUM> may be included to provide an advancing mechanism, which may include a lever <NUM>, an arm <NUM>, and a pawl <NUM> assembly configured to enable a user to retract a spring <NUM> while loading cartridges. More specifically, an advancing mechanism or process may include the components and steps required to extend or rotate a lever <NUM> to increase a moment arm, turn a wheel <NUM>, load cartridges, and release a lever <NUM> while returning. Rotating the lever <NUM> also adds the advantage that one can hold the lever <NUM>, and thus reduce spring pressure, while loading cartridges.

The arm return spring <NUM> may be provided to ensure the arm <NUM> is returned to and/or remains biased towards a starting position after each advancing motion. In some other cases, the arm return spring <NUM> may be provided to ensure that the height of the arm <NUM> does not exceed a threshold. The advancing mechanism may be configured to advance the wheel <NUM> such that one or more cartridges may be loaded after advancing the wheel <NUM>. With the advancing mechanism, the magazine can be more easily loaded without having to release spring tension due to the loading process. Therefore, the spring <NUM> does not have to be wound after loading, thus improving cartridge feed consistency, weapon reliability, and safety. The spring <NUM> is also configured such that an outermost end is fixed relative to the drum body <NUM>, while the innermost end rotates. It should also be understood that for the purpose of this document, the term "advance" may include both linear and rotational movement. For example, advancing a wheel includes rotating the wheel, while advancing a follower assembly may include causing a follower assembly to travel in a generally spiraled path such as through a spiral track or in a generally straight path, such as through a feed tower.

In some embodiments, the lever <NUM> is generally positioned near the outer diameter of the front cover <NUM> and is configured to cause a pawl <NUM> to selectively engage the wheel <NUM>. In turn, the wheel <NUM> may engage the spindle <NUM> of the follower assembly <NUM>, seen in <FIG>, to retract the spring and follower assembly <NUM> for loading cartridges. The advancing mechanism including a pawl <NUM> and lever <NUM> generally increases the moment arm applied to the spindle <NUM> when the lever <NUM> is used, thus improving the ease of use of the drum magazine assembly <NUM>. The lever <NUM> itself may have a grip <NUM> attached to a pivot body <NUM>; the lever <NUM> may also have an advancement lock feature having a clearance groove <NUM> in the pivot body <NUM>, a locking ridge <NUM>, and/or a lever lock <NUM>. In some examples, the advancement lock feature, including the groove <NUM> and locking ridge <NUM>, may be provided to increase reliability in the use of the magazine. Specifically, when the lever <NUM> is in the biased closed position, the groove <NUM> may be rotated away from the locking ridge <NUM> in the front cover <NUM>, causing the pivot body <NUM> to abut the locking ridge <NUM> should one attempt to operate the lever <NUM> when the lever is closed. The pivot body <NUM> is configured to rotate about axis D, shown in <FIG>, such as within a passage <NUM> of the arm <NUM>, and to cause the pawl <NUM> to engage the wheel <NUM> for retracting the spring.

For instance, the pawl <NUM> may be engaged by the lever <NUM> at a notch in a shaft (not shown). Specifically, a pawl pin assembly <NUM> have a pin and a biasing spring and positioned within the lever <NUM> may bottom out on a first side of the notch, thus causing the pawl to rotate away from the wheel <NUM> when the lever <NUM> is in the closed position. When the lever <NUM> is opened, the pawl pin assembly <NUM> is configured to push against the other side of the notch, thus allowing the pawl <NUM> to advance over the teeth of the wheel <NUM> or engage the teeth <NUM> in a ratcheting configuration. Due to a spring assembly, the pawl pin assembly <NUM> may cause the pawl <NUM> to be biased against the wheel <NUM> when the lever <NUM> is in the open position, thus ensuring the pawl <NUM> engages the teeth <NUM> of the wheel <NUM> when the lever <NUM> is being operated.

The grip <NUM> is configured to allow a user to grasp and rotate the lever <NUM> relative to the arm <NUM>. With this motion, the lever <NUM> may be moved from a biased closed position to an open position. Moving the lever <NUM> to the open position may serve to increase the length of the moment arm, and hence the torque to be applied, to the spindle <NUM>. It should be understood that, although movement is discussed as being achieved using a rotating mechanism, movement can be achieved in some embodiments using a telescoping motion.

The lever lock <NUM> may be configured to prevent the lever <NUM> from being opened when the drum magazine assembly <NUM> is installed in a weapon. This lever lock <NUM> may prevent accidental activation of the lever <NUM>, especially when the magazine <NUM> is being used as a weapon-stabilizing support, or is being used in an environment in which branches, debris, load bearing equipment, or the operator could inadvertently entangle or push on the lever <NUM>. In some examples, the lever lock <NUM> of the lever <NUM> may be configured to operate with a variety of weapons. Further, although the lever lock <NUM> is depicted as having a particular profile or shape, it is contemplated that the lever lock <NUM> include any shape suitable for the purpose of preventing the lever <NUM> from being opened when the magazine assembly <NUM> is installed in a weapon. As another example, the lever lock <NUM> could comprise a latch safety, catch, or any other feature, as an alternative to, or in addition to, a blocking mechanism, to prevent the lever <NUM> from being activated when the magazine <NUM> is used.

As previously mentioned, the drum body <NUM> and the drum magazine assembly <NUM> may be configured such that a focal point of each cartridge, regardless of where the cartridges are located in the drum magazine assembly <NUM>, substantially converges at a single point P at a distance D from the drum magazine assembly <NUM>. This is achieved in part by including a curvature to the rear cover <NUM>, as well as a curvature to the spiral track of the drum magazine assembly.

Turning now to <FIG> and <FIG>, the follower assembly <NUM> is discussed in detail. In some examples, the follower assembly <NUM> may implement aspects of the follower discussed above in relation to <FIG>. The follower assembly <NUM> may have an inner spindle slider <NUM>, an outer spindle slider <NUM>, a spindle <NUM>, a plurality of follower dummy rollers <NUM>, a plurality of follower dummies <NUM>, a leading follower dummy roller <NUM>, a leading follower dummy <NUM>, and a plurality of follower links <NUM>, or links <NUM> for short. For ease of reference, the term dummy cartridge <NUM> may be used to reference a combination of a follower dummy roller <NUM> and a follower dummy <NUM>. The terms first dummy cartridge <NUM> or leading dummy cartridge <NUM> may be used to reference the combination of the leading follower dummy roller <NUM> and the leading follower dummy <NUM>.

In some embodiments, one or more of the follower dummy rollers <NUM> may rotate relative to the respective follower dummies <NUM>, which may also rotate relative to the spiral track of the drum. That is, a front portion of a dummy cartridge <NUM> may rotate relative to a rear portion of a dummy cartridge <NUM>. Similarly, a front portion of a leading dummy cartridge <NUM> may rotate relative to a rear portion of a leading dummy cartridge <NUM>. Allowing the front and rear portions of dummy cartridges <NUM>, <NUM> to rotate relative to each other as they pass through the spiral track further minimizes the frictional forces between the follower assembly <NUM> and the drum body assembly <NUM>.

The follower assembly <NUM> may include a sufficient number of dummy cartridges <NUM> so as to ensure that, when fully extended, the feed tower assembly <NUM> is approximately filled with the dummy cartridges <NUM> including the first dummy cartridge <NUM>. Filling the feed tower assembly <NUM> with the dummy cartridges <NUM> allows the torsional spring <NUM> to apply a linear force on the cartridge stack through the feed tower, eliminating the need for a mechanical pusher arm. As will be understood by those skilled in the art, the overall purpose of the follower assembly <NUM> is to maintain loaded cartridges or the first dummy cartridge <NUM> biased towards a feed lip of the feed tower assembly <NUM>. Each crank action of the lever <NUM> causes the follower assembly <NUM> to retract enough to allow at least one cartridge to be loaded. However, the follower assembly <NUM> may retract enough to allow two or more cartridges to be loaded. Particularly when the follower assembly <NUM> is near a fully extended position, more cartridges may be loaded after a single advancing motion. When the follower assembly <NUM> is or moves closer to a fully retracted position, fewer cartridges may be inserted. Upon release of the lever <NUM>, the follower assembly <NUM> resumes the bias towards the feed lip.

In the present disclosure, and as seen in <FIG> and <FIG>, the plurality of dummy cartridges <NUM>, <NUM> are linked by a plurality of links <NUM>, such that each dummy cartridge <NUM> is allowed to rotate within each link <NUM> independently of the other dummy cartridges <NUM> and the first dummy cartridge <NUM>. This independent rolling reduces sliding friction substantially as the dummy cartridges of the follower assembly <NUM> wind through the spiral track <NUM>.

To achieve this independent rotation, all spring force is carried by the stacked follower links <NUM> in a kinetic chain, to allow independent rotation of the dummy cartridges <NUM>, thereby minimizing sliding friction. It should be noted that the first dummy cartridge <NUM> may be keyed to not rotate, so as to enable a bolt catch function to be provided. Naturally, if a bolt catch function is not desired, the first dummy cartridge <NUM> may be configured to rotate just like the remaining dummy cartridges. It is also noted that it is not a requirement that the entire first dummy cartridge <NUM> not rotate. That is, the leading follower dummy <NUM> may be configured to rotate relative to the leading follower dummy roller <NUM>, so as to minimize friction while still retaining a bolt catch function. The last dummy cartridge <NUM>, that is, the dummy cartridge <NUM> closest to the spindle <NUM> when the follower assembly is installed in the magazine assembly <NUM>, is configured to allow the inner spindle slider <NUM> to move along an axis of the dummy cartridge <NUM>, or the follower dummy roller <NUM>, so as to compensate for changes in the position of the dummy cartridges <NUM> relative to the plane define by axes B-C or a rear portion of the drum magazine assembly <NUM>, illustrated in <FIG>.

<FIG> illustrates a feed tower retention mechanism. As seen, the feed tower <NUM> includes a pair of mounting ribs <NUM> (or engagement ribs) configured to interface with a pair of mounting slots <NUM> in the drum body <NUM>. The drum body <NUM> also has a pair of protrusions <NUM> that are retained by the rear cover <NUM>. Retaining clips <NUM> are further provided to maintain the front cover <NUM>, the drum body <NUM>, and the rear cover <NUM> in an assembled state. With a brief review of <FIG>, it can be seen that the mounting ribs <NUM> stop short of the rear cover <NUM> when the feed tower <NUM> is assembled to the drum body <NUM>. In some cases, the protrusions <NUM> of the drum body <NUM> may nest under the rear cover <NUM>. By locking the feed tower in this manner, the present design exhibits much less potential for movement, as compared to currently-available designs. This also provides for reduced tolerance stacking problems, as well as improved strength and alignment as compared to currently-available designs.

In some cases, the spiral track in the drum may serve to guide single stack rounds in the drum body <NUM> until they get above the arm <NUM> of the front cover assembly <NUM> and pushed into a single or double stack portion of the feed tower <NUM>. It should be noted that, while the cartridges are generally stacked in a singular fashion within the drum body, they may appear as double stacked to the action/receiver of the firearm.

<FIG> illustrates a method <NUM> of manufacturing a magazine according to one or more embodiments of the disclosure. In some cases, method <NUM> may implement one or more aspects of <FIG> discussed above.

At <NUM>, a magazine comprising an elongated casing or feed tower having at least a distal end and a proximal end, and two sides longer than the distal and proximal ends, may be provided. In some examples, providing the magazine may further comprise forming one or more openings in the distal and/or proximal ends of the elongated casing or feed tower.

At <NUM>, a bolt catch mechanism may be provided in the magazine, where the bolt catch may be arranged at least partially inside and within an upper portion of the elongated casing or the feed tower.

In some examples, the bolt catch mechanism be coupled to the elongated casing or feed tower via one of <NUM>-a or <NUM>-b.

In some embodiments, at <NUM>-a, the bolt catch mechanism may be pivotally coupled to the elongated casing or feed tower at a pivot axis. In some cases, the pivot axis may be arranged in an opening in the distal end of the elongated casing or feed tower, and the bolt catch mechanism may be pivotable around the pivot axis towards the distal end (i.e., pivotally coupled within the distal opening). In such cases, a bolt-engagement portion of the bolt catch mechanism may be arranged within a proximal opening and may be configured to pivotally move up and down within the proximal opening, as described in relation to <FIG>. In some other cases, the pivot axis may be arranged in an opening in the proximal end of the elongated casing or the feed tower, and the bolt catch mechanism may be arranged within a distal opening and may be configured to pivotally move up and down with the distal opening, as described in relation to <FIG>.

Optionally, in some embodiments, the bolt catch mechanism may be coupled to the elongated casing or feed tower via a sliding engagement, at <NUM>-b, also described in relation to <FIG>. In some cases, the bolt catch mechanism may be slidable along a path parallel with a follower once a tab contacts a lower surface of the bolt catch mechanism, as further described below.

At <NUM>, a follower may be provided in the magazine, where the follower comprises two or more dummy cartridges and two or more links, one surrounding at least a portion of each dummy cartridge.

At <NUM>, a tab may be provided on the follower, where the tab may extend sideways from the follower. Optionally, the tab may extend sideways from one of the links or one of the dummy cartridges on the follower. In some cases, the tab may extend towards one of the two sides of the magazine (or toward the distal end or toward the proximal end), for instance, a side on which the bolt catch mechanism is arranged. Although not shown, where the tab extends toward the distal or proximal end of the feed tower or elongated casing, the tab may interface with a bolt lock mechanism also arranged on the same distal or proximal end of the follower. Alternatively, the bolt lock mechanism could still comprise an arm running along one side of the follower, but further including a flange that wraps around from the side to the distal or proximal end of the follower so as to interface with the proximally or distally extending tab. This variation on the bolt lock mechanism can also pivot or slide vertically.

In some embodiments, at <NUM>, the tab may be arranged such that the tab contacts and biases upward the bolt catch mechanism into a position configured to engage a bolt catch of a firearm that the magazine is engaged with when the follower approaches a top of the magazine. In some embodiments, if the bolt catch mechanism is pivotable at a distal end, the tab may be arranged on the follower to contact the bolt catch mechanism, for instance, towards the proximal end of the elongated casing or feed tower. In some other cases, if the tab extends roughly sideways from at least one of the links or dummy cartridges (or toward the distal end or toward the proximal end), the tab may be arranged such that when the two or more dummy cartridges move to a top of the feed tower, the tab biases the pivotable bolt catch mechanism upward into an engaged position.

In yet other cases, if the bolt catch mechanism is slidable along a path parallel with the follower (i.e., bolt catch mechanism is coupled to the elongated casing or feed tower via a sliding engagement), the tab may be arranged to at least contact a lower surface of the bolt catch mechanism. It should be noted that, irrespective of the location of the tab (e.g., extending sideways from follower, dummy cartridges, links, etc., as well as towards either of the proximal or distal end), the tab may be arranged such that an upward motion of the tab under a curved lower portion of the bolt catch mechanism may lead to a sliding or swinging motion of the bolt catch mechanism, where the sliding motion is parallel with the follower.

<FIG> illustrates a method <NUM> of using a magazine assembly comprising a bolt catch mechanism, according to one or more embodiments of the disclosure. In some cases, method <NUM> may implement one or more aspects of <FIG> discussed above. In some examples, the magazine may be manufactured using the method <NUM>, as described above in relation to <FIG>.

In some embodiments, at <NUM>, the method may include loading and installing a magazine having a feed mechanism into a weapon, such as a firearm, where the magazine comprises at least an elongated casing or feed tower, a bolt catch mechanism, a follower, and a tab extending sideways from the follower, or from one of the links or one of the dummy cartridges (or toward the distal end or toward the proximal end). In some examples, the follower comprises a plurality of dummy cartridges coupled via movable links, where the tab extends from one of the movable links or one of the plurality of dummy cartridges. The tab may be arranged towards one of the proximal or distal ends of the elongated casing or feed tower.

Further, the magazine may be a single stack, double stack, or drum magazine. In some cases, such as when the magazine is a drum magazine, the drum magazine may include a drum coupled to a bottom of the feed tower, where the drum has a constant internal curve that causes axes of the cartridges in the drum to intersect in front of the drum. In some embodiments, the drum and feed tower may share a constant internal curve.

In some cases, loading a magazine at <NUM> may include installing the magazine into a weapon having a closed bolt. Loading a magazine at <NUM> may include causing a closed bolt to push a first cartridge from a start position to a displaced position, and against a second cartridge or a leading follower dummy. Loading a magazine at <NUM> may further include preventing a third cartridge or a second dummy cartridge from retracting into the magazine assembly while the first cartridge is in the displaced position.

In some embodiments, the method <NUM> may further include blocking a lever at <NUM>, where blocking a lever includes causing the weapon to block the lever at a lever lock on the lever, thereby preventing the lever from being opened. Blocking a lever at <NUM> may be achieved using, for example, a lever <NUM> as described with reference to <FIG>.

In some cases, the method <NUM> may comprise firing the weapon at <NUM> until a final cartridge from the magazine is presented into a chamber of the firearm via upward movement of the follower in the elongated casing or feed tower of the magazine. In some embodiments, firing the weapon at <NUM> may include allowing loaded cartridges to advance through the magazine and/or a feed mechanism as described with reference to any one of the preceding figures.

In some cases, the method <NUM> may also include engaging a bolt catch at <NUM>. Engaging a bolt catch at <NUM> may be achieved using components similar to those discussed with reference to at least <FIG> above. For instance, the bolt catch may be engaged at <NUM> by contacting a lower surface of the bolt catch mechanism of the magazine with the tab extending sideways from the follower (or toward the distal end or toward the proximal end), or from one of the links or one of the dummy cartridges. In some cases, engaging a bolt catch at <NUM> includes causing a bolt catch engagement feature, such as a sideways extending tab (or toward the distal end or toward the proximal end), to contact and force the bolt catch mechanism of the magazine upward into an engaged position, and secure the bolt catch of the firearm that the magazine is engaged with in a locked position with a bolt engagement portion of the bolt catch mechanism as a result of upward movement of the bolt catch mechanism.

In some cases, the bolt catch mechanism is pivotable around a pivot axis in one of a distal or proximal end of a feed tower of the magazine. The pivot axis may be situated at an opposite end to the tab in the feed tower. In some other cases, the bolt catch mechanism may be slidable along a path parallel with the follower once the tab contacts a lower surface of the bolt catch mechanism. In some cases, engaging the bolt catch on a weapon after a final cartridge is fired may serve to simplifying loading of a subsequent loaded magazine.

The method <NUM> may further include disengaging the magazine at <NUM> from a weapon, which may be achieved using any means, components, or actions known to those skilled in the art.

Claim 1:
A magazine (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
an elongated casing or feed tower (<NUM>, <NUM>) having at least a distal end and a proximal end, and two sides longer than the distal and proximal ends;
a follower (<NUM>) having a tab (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) extending sideways toward one of the two sides, wherein the tab is positioned near one of a distal end or a proximal end of the follower; and
a bolt catch mechanism (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) arranged at least partially inside and near a top of the elongated casing or feed tower, wherein the tab is arranged to contact and bias upward the bolt catch mechanism into a position configured to engage a bolt catch (<NUM>, <NUM>, <NUM>, <NUM>) or slide stop of a firearm that the magazine is engaged with, and wherein the bolt catch mechanism comprises a bolt engagement portion (<NUM>) arranged on a same one of the distal end or the proximal end of the follower as the tab.