Apparatus, systems, and methods for an adjustable magazine lockup. A magazine body includes a slot in a first side with feed lips connected to the top side. The feed lips have a top edge positioned away from the top side of the magazine body. A first insert with a first lockup notch may be positioned within the slot so that there is a first distance from the top edge of the feed lips to a centerline of the first lockup notch. The insert may be replaced to change to the top edge of the feed lips. A second insert having a second lockup notch may be inserted into the slot in the first side of the magazine body to increase the distance and a third insert having a third lockup notch may be inserted into the slot in the first side of the magazine body to decrease the distance.

A firearm comprising: (i) an ammunition magazine which automatically ejects from the lower receiver of the firearm when the ammunition magazine is spent; (ii) a control group comprising a magazine release mechanism for releasing the magazine catch so that the ammunition magazine is detachable from the lower receiver, a bolt catch engage mechanism for engaging the bolt catch with the bolt carrier and retaining the bolt carrier in the retracted position, and a bolt catch release mechanism for releasing the bolt catch from the bolt carrier and allowing the bolt carrier to move forward, wherein the control group components can be operated by the user on either the left side or right side of the firearm; and (iii) optionally, a charging handle which can be operated by the user on either the left side or right side of the firearm.

A firearm comprising: (i) an ammunition magazine which automatically ejects from the lower receiver of the firearm when the ammunition magazine is spent; (ii) a control group comprising a magazine release mechanism for releasing the magazine catch so that the ammunition magazine is detachable from the lower receiver, a bolt catch engage mechanism for engaging the bolt catch with the bolt carrier and retaining the bolt carrier in the retracted position, and a bolt catch release mechanism for releasing the bolt catch from the bolt carrier and allowing the bolt carrier to move forward, wherein the control group components can be operated by the user on either the left side or right side of the firearm; and (iii) optionally, a charging handle which can be operated by the user on either the left side or right side of the firearm.

Embodiments of the invention include a firearm system and method of assembly of the firearm system including a receiver complex including a receiver coupled to a forward receiver. A feed port is positioned between the receiver and the forward receiver, and a striker coil assembly is positioned proximate the receiver, and includes a plurality of strikers each extending at least partially through a coil. An interchangeable barrel is coupled to the forward receiver forming a breech. In some embodiments, the firearm system includes a breech that includes a plurality of side-by-side bores of the barrel. Some embodiments include a magazine coupled to the receiver complex adjacent the feedport to simultaneously feed more than one dischargeable projectile into the feedport with a single charge block. In some embodiments, the charge block includes a plurality of chambers and a plurality of projectiles positioned within the plurality of chambers.

Embodiments of the invention include a firearm system and method of assembly of the firearm system including a receiver complex including a receiver coupled to a forward receiver. A feed port is positioned between the receiver and the forward receiver, and a striker coil assembly is positioned proximate the receiver, and includes a plurality of strikers each extending at least partially through a coil. An interchangeable barrel is coupled to the forward receiver forming a breech. In some embodiments, the firearm system includes a breech that includes a plurality of side-by-side bores of the barrel. Some embodiments include a magazine coupled to the receiver complex adjacent the feedport to simultaneously feed more than one dischargeable projectile into the feedport with a single charge block. In some embodiments, the charge block includes a plurality of chambers and a plurality of projectiles positioned within the plurality of chambers.

A detachable box magazine for firearms includes a hollow magazine tube extending longitudinally along a median plane. The magazine tube defines a single-stack portion extending substantially to an upper tube end that defines an upper tube opening. The magazine tube has a double-stack portion positioned below the single-stack portion and extending to a bottom tube end. For example, front portions of the opposite tube sidewalls have a stepped shape between the upper tube end and the double-stack portion, and the rear portions of the sidewalls have a linear taper between the upper tube end and the double-stack portion.

A detachable box magazine for firearms includes a hollow magazine tube extending longitudinally along a median plane. The magazine tube defines a single-stack portion extending substantially to an upper tube end that defines an upper tube opening. The magazine tube has a double-stack portion positioned below the single-stack portion and extending to a bottom tube end. For example, front portions of the opposite tube sidewalls have a stepped shape between the upper tube end and the double-stack portion, and the rear portions of the sidewalls have a linear taper between the upper tube end and the double-stack portion.

An overmolded/through-molded firearm magazine including at least some of one or more wall portions defining a magazine core, wherein the magazine core extends from a substantially open top portion to a substantially open bottom portion and at least partially defines a core cavity; at least one core aperture/recess formed through a portion of one or more of the one or more wall portions; and an overmolded body formed atop at least a portion of an exterior surface of the magazine core, wherein at least a portion of the overmolded body extends at least partially through the at least one core aperture/recess, forming a through-core protrusion.

An overmolded/through-molded firearm magazine including at least some of one or more wall portions defining a magazine core, wherein the magazine core extends from a substantially open top portion to a substantially open bottom portion and at least partially defines a core cavity; at least one core aperture/recess formed through a portion of one or more of the one or more wall portions; and an overmolded body formed atop at least a portion of an exterior surface of the magazine core, wherein at least a portion of the overmolded body extends at least partially through the at least one core aperture/recess, forming a through-core protrusion.

A detachable box magazine for firearms includes a hollow magazine tube extending longitudinally along a median plane. The magazine tube defines a single-stack portion extending to an upper tube end with an upper tube opening. The magazine tube defines a double-stack portion positioned below the single-stack portion and extending to a bottom tube end with a bottom tube opening. For example, front portions of the opposite tube sidewalls have a stepped shape between the upper tube end and the double-stack portion, and the rear portions of the sidewalls have a linear taper between the upper tube end and the double-stack portion.