Generally, a device for counting used munitions may include at least one sensor and at least one processor attachable to a firearm. The sensor(s) may be configured to generate at least one sensor signal, having signal values, in response to movement of at least one of: the firearm or at least one movable member of the firearm. The processor(s) may be configured to receive the sensor signal(s) from the sensor(s), and to detect, based on the signal values of the sensor signal(s) and a predetermined signal threshold, a discharge of the firearm. The processor(s) may be configured to determine a number of remaining cartridges in a magazine of the firearm, based on the detections of the discharges thereof. The device may further include at least one indicator configured to generate at least one notification concerning the number of remaining cartridges in the magazine.

Generally, a device for counting used munitions may include at least one sensor and at least one processor attachable to a firearm. The sensor(s) may be configured to generate at least one sensor signal, having signal values, in response to movement of at least one of: the firearm or at least one movable member of the firearm. The processor(s) may be configured to receive the sensor signal(s) from the sensor(s), and to detect, based on the signal values of the sensor signal(s) and a predetermined signal threshold, a discharge of the firearm. The processor(s) may be configured to determine a number of remaining cartridges in a magazine of the firearm, based on the detections of the discharges thereof. The device may further include at least one indicator configured to generate at least one notification concerning the number of remaining cartridges in the magazine.

A device implementable on a firearm includes a magazine extension housing and a locking plate. The magazine extension housing is attachable to a bottom opening of a magazine well of a magazine that is implementable on the firearm. The locking plate is receivable in a portion of the magazine extension housing such that the locking plate is configured to lock the magazine extension housing to the magazine well when the magazine extension housing is attached to the magazine well of the magazine.

A device implementable on a firearm includes a magazine extension housing and a locking plate. The magazine extension housing is attachable to a bottom opening of a magazine well of a magazine that is implementable on the firearm. The locking plate is receivable in a portion of the magazine extension housing such that the locking plate is configured to lock the magazine extension housing to the magazine well when the magazine extension housing is attached to the magazine well of the magazine.

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.

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.

A sight assembly for a firearm includes an optical sight configured for mounting to a firearm. The optical sight includes a sight body retaining a lens and has a point-of-aim indicator visible on the lens. A light source on the sight body is configured to communicate a firearm status to a user, such as whether a round is chambered in a chamber of the firearm. In one example, the sight assembly can be mounted to a handgun or a rifle. In some embodiments, the optical sight is configured as a reflex sight.

A sight assembly for a firearm includes an optical sight configured for mounting to a firearm. The optical sight includes a sight body retaining a lens and has a point-of-aim indicator visible on the lens. A light source on the sight body is configured to communicate a firearm status to a user, such as whether a round is chambered in a chamber of the firearm. In one example, the sight assembly can be mounted to a handgun or a rifle. In some embodiments, the optical sight is configured as a reflex sight.

The present disclosure provides ammunition magazines for bottom-loading a 5.7×28 mm ammunition round or a 4.6×30 mm ammunition round into a standard AR-15 or M16 upper receiver.

A linear encoder may be used to accurately determine a number of cartridges within a magazine. Further, using a set of magnetic sensors within a buffer tube of a firearm, it is possible to determine whether a cartridge is loaded within a chamber of the weapon and/or whether the firearm is jammed. The determination of cartridges within the magazine in conjunction with the determination of whether a cartridge is in a chamber of a firearm can give a user an accurate ammunition count. Further, the use of the linear encoder makes it possible to accurately determine the cartridge count when different cartridges are loaded into the magazine or when the magazine degrades in quality over time. Moreover, the ability for magazines to communicate with a firearm enables a user to determine a total available ammunition to the user in a single display without individually checking each magazine.