Abstract: This disclosure describes a firearm stock or arm brace with an adjustable length of pull. The stock or arm brace can include a body and lower stock, where the body includes a buffer tube receiving aperture and the lower stock includes a hollow cavity with a plunger and two concentric springs therein. One or more buttons can be affixed to sides of the plunger in the hollow cavity that can be used to depress the plunger against the force of one or both of the springs. One of the two springs may be shorter than the other and have a greater spring constant than the longer spring. Depressing the plunger against the taller spring may allow a user to adjust the length of pull while greater pressure and engagement of the second spring allows the stock or arm brace to be removed from a buffer tube or receiver extension.

Abstract: An accessory mounting interface for a firearm, and a related method, are disclosed. The interface has a firearm accessory, a first elongated fastener, and a second fastener rotationally mated to the first elongated fastener. The first elongated fastener has right-handed threading and is arranged through a through hole in the firearm accessory with a first end extending below first and second halves of a first slot protrusion of the firearm accessory. The second fastener has a length greater than a width, the length measured along a longitudinal axis of the second fastener, the second fastener having a plurality of straight edges. At least one of the plurality of straight edges prevents the second fastener from rotating further than a closed position when the at least one of the straight edges abuts a sidewall of an elongated slot in the firearm.

Abstract: A magazine assembly for a firearm and a related method are disclosed. The assembly has a magazine housing defining a track, and a follower assembly. The magazine housing is configured to constrain a cartridge as the cartridge is moved within the magazine assembly such that majority of a proximal surface area of the cartridge does not contact the magazine housing, and a distal tip of the cartridge does not contact the magazine housing.

Abstract: This disclosure describes systems, methods, and apparatus for a quick-release adapter between two tripod/bipod/monopod interfaces, wherein a clamping side of the adapter is configured to clamp onto two different types of interfaces or rails such as Arca and Picatinny/Weaver/NATO.

Abstract: An interface for coupling a bipod to a sling stud of a firearm forend. The interface can include two pawls that pivot to release or grasp the sling stud. The pawls can be biased upward via a detent that rides within a vertical aperture in a pivot holder. The pivot holder can move up and down within a vertical aperture in a mounting plate of the interface, and via this movement the pawls may be forced open or closed. A bottom surface of one or both pawls can include an irregular surface different portions of which interface with a top of the detent depending on a vertical position of the pivot holder within the aperture in the mounting plate.

Abstract: A locking case including a base and a lid includes a latch recess integrated into an outer profile of the case, and a latch installed within the latch recess. The latch includes a latch handle including a first end, rotatably coupled with the lid, and a second end including an end protrusion configured for removably engaging with a first portion of the base. The latch also includes a passthrough feature for accommodating a lock mechanism therethrough. The latch handle is larger than the locking mechanism. The latch recess fully accommodates the latch and most or all of the lock mechanism therein when the second end of the latch handle is engaged with the first portion of the base and the lock mechanism is installed through the passthrough feature such that the latch and the lock mechanism do not substantially protrude from the outer profile of the case.

Abstract: An accessory mounting interface for a firearm, and a related method, are disclosed. The interface has a firearm accessory, a first elongated fastener, and a second fastener rotationally mated to the first elongated fastener. The first elongated fastener has right-handed threading and is arranged through a through hole in the firearm accessory with a first end extending below first and second halves of a first slot protrusion of the firearm accessory. The second fastener has a length greater than a width, the length measured along a longitudinal axis of the second fastener, the second fastener having a plurality of straight edges. At least one of the plurality of straight edges prevents the second fastener from rotating further than a closed position when the at least one of the straight edges abuts a sidewall of an elongated slot in the firearm.

Abstract: This disclosure describes systems, methods, and apparatus for detecting and displaying a number of rounds in a firearm magazine comprising a maximum number of N rounds. The magazine may comprise a follower, magnets on the follower, and <N magnetic switches arranged along a path of the magnets when the follower moves along a length of the magazine, the switches configured to activate based on a magnetic field exceeding a threshold, and a first antenna arranged on an inside of the magazine and parallel to a firing direction of the firearm, and configured to wirelessly transmit a round count indication to a second antenna on the firearm, the round count indication based on the round count data, the second antenna affixed to an inside of a magazine well of the firearm and mostly overlapping with the first antenna.

Abstract: Leaf springs for use in a firearm magazine are described. The leaf springs comprising an inner edge, an outer edge, and a channel, and configured to facilitate movement of cartridges within a feed tower of the firearm magazine. The leaf springs can be in a flexed or unflexed position, wherein downward movement of the cartridges in the feed tower outwardly flex the leaf springs into the flexed position to facilitate downward translation of the cartridges by forcing the inner edge of the leaf springs away from the cartridges, and in the unflexed position, the inner edge of the leaf springs is parallel or substantially parallel to an edge of the cartridges in the feed tower.

Abstract: An interface for coupling a bipod to a sling stud of a firearm forend. The interface can include two pawls that pivot to release or grasp the sling stud. The pawls can be biased upward via a detent that rides within a vertical aperture in a pivot holder. The pivot holder can move up and down within a vertical aperture in a mounting plate of the interface, and via this movement the pawls may be forced open or closed. A bottom surface of one or both pawls can include an irregular surface different portions of which interface with a top of the detent depending on a vertical position of the pivot holder within the aperture in the mounting plate.

Abstract: This disclosure describes systems, methods, and apparatus for detecting and displaying a number of rounds in a firearm magazine comprising a maximum number of N rounds. The magazine may comprise a follower, magnets on the follower, and <N magnetic switches arranged along a path of the magnets when the follower moves along a length of the magazine, the switches configured to activate based on a magnetic field exceeding a threshold, and a first antenna arranged on an inside of the magazine and parallel to a firing direction of the firearm, and configured to wirelessly transmit a round count indication to a second antenna on the firearm, the round count indication based on the round count data, the second antenna affixed to an inside of a magazine well of the firearm and mostly overlapping with the first antenna.

Abstract: This disclosure describes systems, methods, and apparatus for a bipod having pivot and cant functionality built into a unified cant/pivot assembly, housing, and pivot block. Rotation of a locking knob under the housing can gradually increase or decrease friction of the cant and pivoting degrees of freedom. Sufficient loosening of the locking knob can allow a pivot block to be lifted from the housing and rotated 18°, and then retightened to lock in a given pivot position.

Abstract: A sighting system for a firearm and related methods are disclosed. The sighting system has front and rear flip-up sights, wherein the front sight comprises a flip-up portion having an aperture through which a sight post can partially extend; a knob comprising one or more notches on a first side and the sight post extending from a second side; at least one detent arranged to face and interact with the one or more notches. The knob is configured to rotate about a first axis, where the rotation causes the sight post to move in a first direction along the first axis; tilting of the knob in a second direction based on the detent interfacing with the notches; and tilting of the sight post in the second direction, thereby forcing at least a portion of the sight post to press against the aperture, or a combination thereof.

Abstract: An organizer system for use with a case including a base and a lid configured to be matingly coupled together for containing an object therein is disclosed. The organizer system includes a panel system including at least one panel, the at least one panel including a plurality of cutouts formed therein, and a plurality of mounting blocks, each one of the plurality of mounting blocks including a block body and at least one stud. The stud is configured to be removably insertable into one of the plurality of cutouts. When the mounting blocks are inserted into the cutouts adjacent to the object then the base and the lid are coupled together, the panel system and the mounting blocks cooperate to prevent shifting of the object within the case. A method for storing an object in a case using an organizer system is also disclosed.

Abstract: This disclosure describes systems, methods, and apparatus for a bipod having pivot and cant functionality built into a unified cant/pivot assembly, housing, and pivot block. Rotation of a locking knob under the housing can gradually increase or decrease friction of the cant and pivoting degrees of freedom. Sufficient loosening of the locking knob can allow a pivot block to be lifted from the housing and rotated 180°, and then retightened to lock in a given pivot position. Before this 180 rotation of the pivot block, the pivot block and hence the firearm is free to pivot up to 10°, or up to 20°, or up to 30°.

Abstract: This disclosure describes systems, methods, and apparatus for detecting and displaying a number of rounds in a firearm magazine comprising a maximum number of N rounds. The magazine may comprise a follower, magnets on the follower, and <N magnetic-field-sensing sensors arranged along a path of the magnets when the follower moves along a length of the magazine, the sensors generating round count data based on a position of the one or more magnets relative to the <N magnetic-field-sensing sensors, and a first substantially flat antenna arranged on an inside of the magazine and configured to wirelessly transmit a round count indication to a second substantially flat antenna on the firearm, the round count indication based on the round count data, the second substantially flat antenna affixed to an inside of a magazine well of the firearm and mostly overlapping with the first substantially flat antenna.