Abstract: A drum magazine assembly and methods are described. A drum assembly has a follower assembly, a drum body, a spring assembly, and a feed tower assembly. The follower assembly biases cartridges towards an exit of the feed tower assembly. The follower assembly has a plurality of dummy cartridges, the plurality of dummy cartridges having a leading dummy cartridge and a last dummy cartridge, and a plurality of links including a leading link and a last link. The last dummy cartridge rotates relative to the last link and the leading link, and the leading dummy cartridge has a bolt catch engagement feature.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.

Abstract: A quick detach mount and method are disclosed. The mount includes an accessory receiving portion shaped to receive a quick detach interface, and a first arm extending from the accessory receiving portion. The quick detach mount is shaped to receive a first fastener and a second fastener, whereby the quick detach mount is shaped distribute a force from the accessory receiving portion.

Abstract: This disclosure describes systems, methods, and apparatus for a barrel support for a for a firearm stock. In one example, the barrel support has an elongate frame with a longitudinal axis extending between a fore portion and an aft portion, a first concave barrel recess shaped to support a first barrel, the first concave barrel recess positioned on a first side of the elongate frame. The exemplary barrel support also has a second concave barrel recess shaped to support a second barrel, the second concave barrel recess positioned on a second side of the elongate frame. In this example the first barrel is a tapered barrel, and the second barrel is a straight barrel.

Abstract: A follower for a firearm magazine is provided. In some embodiments, the follower has: a cartridge platform coupling a first wall to a second wall. The first wall, the second wall, and the platform define a receiving space for receiving at least a portion of a magazine spring. At least one of the first wall or the second wall has a nonlinear end profile shaped to translate a lateral spring force into a longitudinal spring force.

Abstract: This disclosure describes systems, methods, and apparatus for a selectable barrel support that can be inserted into a forend of a firearm stock to support a first barrel type and flipped, rotated, or otherwise moved to support a second barrel type (or third or fourth barrel types). A tensioning mechanism is provided. Bull and tapered barrels are examples of two barrel types that the selectable barrel support can be used to support. The selectable barrel support enables a firearm owner or gunsmith to exchange barrel types on a firearm without having to switch out the firearm stock.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.

Abstract: A follower for a firearm magazine is provided. In some embodiments, the follower has: a platform shaped to interface with a firearm cartridge; a first side face extending longitudinally from the platform and having a first end opposing the platform; and a second side face extending longitudinally from the platform and having a second end opposing the platform. The first side face and the second side face may define a receiving space for receiving at least a portion of a magazine spring. At least one of the first end and the second end may have a nonlinear profile shaped to translate a lateral spring force into a longitudinal spring force.

Abstract: This disclosure describes systems, methods, and apparatus for a selectable barrel support that can be inserted into a forend of a firearm stock to support a first barrel type and flipped, rotated, or otherwise moved to support a second barrel type (or third or fourth barrel types). A tensioning mechanism is provided. Bull and tapered barrels are examples of two barrel types that the selectable barrel support can be used to support. The selectable barrel support enables a firearm owner or gunsmith to exchange barrel types on a firearm without having to switch out the firearm stock.

Abstract: A follower for a firearm magazine is provided. In some embodiments, the follower has: a platform shaped to interface with a firearm cartridge; a first side face extending longitudinally from the platform and having a first end opposing the platform; and a second side face extending longitudinally from the platform and having a second end opposing the platform. The first side face and the second side face may define a receiving space for receiving at least a portion of a magazine spring. At least one of the first end and the second end may have a nonlinear profile shaped to translate a lateral spring force into a longitudinal spring force.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.

Abstract: A padded strap is provided, which comprises a unitary strap member forming a tube and an inserted pad. The unitary strap member has at least two sections, at least one of the sections configured to form a pad casing section which can retain the inserted pad, and the another section comprising a substantially flat section abutting the pad casing section. The area between the pad casing section and the substantially flat section comprises a hollow, tapering transition area. The unitary strap member comprises at least one sealable opening at an end of the unitary strap member. The inserted pad is inserted through the sealable opening and retained in the pad casing section, and the pad is comprised of at least one outer layer of resilient, low-friction material and a cushioning layer.

Abstract: A drum magazine assembly and methods are described. A drum assembly has a follower assembly, a drum body, a spring assembly, and a feed tower assembly. The follower assembly biases cartridges towards an exit of the feed tower assembly. The follower assembly has a plurality of dummy cartridges, the plurality of dummy cartridges having a leading dummy cartridge and a last dummy cartridge, and a plurality of links including a leading link and a last link. The last dummy cartridge rotates relative to the last link and the leading link, and the leading dummy cartridge has a bolt catch engagement feature.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.

Abstract: An improved firearm accessory mounting interface is herein disclosed. The interface can include one or more sets of first and second fasteners that interface through an elongated slot in a firearm in order to mount a firearm accessory to a firearm. The second fastener can be shaped and sized to clear the elongated slot and can, upon clearing the elongated slot, be pivoted to an oblique orientation relative to the elongated slot so that the second fastener cannot be retracted. The first fastener can continue to be turned thus drawing the first and second fasteners toward each other and locking the accessory to the firearm.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.

Abstract: A stock for a firearm is disclosed. The stock comprises a stock-to-firearm interface, and a folding stock assembly hingedly coupled to the stock-to-firearm interface. The stock comprises a folded configuration and an unfolded configuration. The stock-to-firearm interface comprises a modifiable firearm mount, a lock catch, a quick detach mount, and one of a detent notch and a detent. The folding stock assembly comprises a buttstock, a lock for engaging the lock catch in the stock-to-firearm interface to selectively maintain the stock in the unfolded configuration, and the other one of a detent and a detent notch. The detent is shaped to engage the detent notch to selectively maintain the stock in the folded configuration. The quick detach mount is shaped to distribute a carry force between a first surface of the stock-to-firearm interface and at least one of a second surface of the stock-to-firearm interface and a firearm.

Abstract: A gunsmithing block is disclosed. The gunsmithing block has a first end for interfacing with a vice, and a second end shaped to interface with an upper receiver assembly of a firearm, the upper receiver assembly having an upper receiver, a bolt carrier without a bolt, and a barrel extension. The second end has an upper receiver mating portion shaped to interface with an interior region of the upper receiver and an interior region of the barrel extension. Methods of using and making a gunsmithing block are also disclosed.

Abstract: A wrench and a method for performing gunsmithing operations is disclosed. The wrench may have a first end and a second end. The first end may have an integrated two-sided castle nut and flash hider wrench aperture, and the second end may have a tool interface. The aperture may have a plurality of raised elements for engaging indentations in a castle nut, each of the raised elements extending at least one of inwardly from a wall section of the aperture and upwardly from a first face of the wrench. The aperture may have a flash hider cutout portion.

Abstract: An accessory mounting interface for a firearm is provided. The accessory mounting interface has a firearm accessory, a first elongated fastener, a second fastener, and an elongated slot in a firearm. The second fastener has two straight edges parallel to each other, and at least one of the two straight edges prevent the second fastener from rotating beyond a closed position once a portion of the second fastener has passed through and at least partially cleared the elongated slot.