Abstract: An ammunition magazine is disclosed including a tube surrounding a central space and having first and second ends oppositely disposed and having a first opening being positioned at the first end providing access to the central space. A spacer surrounds the tube proximate to the first end. A catch plate is integrally formed with the spacer. A butt plate is attached to the first end and overlies a portion of the spacer. The spacer being is captured between the butt plate and the tube. A fastener is positioned on the catch plate and engages the butt plate to retain the butt plate to the spacer.

Abstract: A combination back strap and grip extender mountable on a grip of a firearm. The grip defines a magazine well. The combination comprises a strap positionable lengthwise along and overlying an anterior portion of said grip. The strap has first and second ends oppositely disposed. The first and second ends are removably attachable to said grip. The grip extender is mounted on said second end of said strap. The grip extender comprises a collar defining a lumen aligned with said magazine well when said strap overlies said grip.

Abstract: A bolt catch is movably mounted on a firearm. A first surface of the bolt catch is configured to engage a bolt to retain the bolt in a first position. The bolt catch has a second surface that is configured to engage a follower of a magazine when the magazine is empty to position the bolt catch in a catching configuration in which the first surface is within a path of travel of the bolt. The bolt catch includes an elongate slot that extends transversely through the bolt catch. A pin extends through the slot of the bolt catch. The bolt catch is configured to pivot about the pin and slide relative to the pin. A spring biases the bolt catch rearwardly. Upon engagement between the bolt and the first surface of the bolt catch, the bolt catch is configured to slide relative to the pin to compress the spring.

Abstract: A combination back strap and grip extender mountable on a grip of a firearm. The grip defines a magazine well. The combination comprises a strap positionable lengthwise along and overlying an anterior portion of said grip. The strap has first and second ends oppositely disposed. The first and second ends are removably attachable to said grip. The grip extender is mounted on said second end of said strap. The grip extender comprises a collar defining a lumen aligned with said magazine well when said strap overlies said grip.

Abstract: An ammunition magazine is disclosed including a tube surrounding a central space and having first and second ends oppositely disposed and having a first opening being positioned at the first end providing access to the central space. A spacer surrounds the tube proximate to the first end. A catch plate is integrally formed with the spacer. A butt plate is attached to the first end and overlies a portion of the spacer. The spacer being is captured between the butt plate and the tube. A fastener is positioned on the catch plate and engages the butt plate to retain the butt plate to the spacer.

Abstract: An action for a firearm uses a rotating barrel on which are mounted lugs and a cam follower. The barrel is positioned coaxially within a tube fixed to the frame of the firearm. A cam, engaged by the cam follower, is also fixed to the frame. A gas space is defined between the tube and the barrel by a thrust surface on the barrel and a reaction surface on the tube. A gas port connects the gas space with the barrel's bore. A slide overlies the tube and defines longitudinally oriented grooves which receive the lugs when the barrel is rotated by interaction between the cam and the cam follower to align the lugs and the grooves. Motion of the barrel is arrested by interaction between the cam and cam follower, and motion of the slide relative to the barrel is permitted when the lugs align and engage the grooves.

Abstract: An action for a firearm uses a rotating barrel on which are mounted lugs and a cam follower. The barrel is positioned coaxially within a tube fixed to the frame of the firearm. A cam, engaged by the cam follower, is also fixed to the frame. A gas space is defined between the tube and the barrel by a thrust surface on the barrel and a reaction surface on the tube. A gas port connects the gas space with the barrel's bore. A slide overlies the tube and defines longitudinally oriented grooves which receive the lugs when the barrel is rotated by interaction between the cam and the cam follower to align the lugs and the grooves. Motion of the barrel is arrested by interaction between the cam and cam follower, and motion of the slide relative to the barrel is permitted when the lugs align and engage the grooves.

Abstract: A trigger return spring assembly mountable on a frame of a firearm includes a trigger mounted on the frame pivoting about a first axis of rotation. A trigger bar attached to the trigger pivots relative to the trigger about a second axis of rotation fixed on the trigger. A bore extends through the trigger along a third axis oriented transversely to and positioned between the first and second axes of rotation. A plunger extends through the bore and is movable along the third axis. A first end of the plunger is attached to the trigger bar and a second end has a retaining surface oriented transversely to the third axis. A shoulder is positioned within the bore proximate to the trigger bar. A compression spring captured within the bore, between the shoulder and the retaining surface, exerts a force pushing the retaining surface away from the shoulder.

Abstract: A magazine safety for a semiautomatic firearm uses two levers connected via a floating pin. The first lever is pivotable into and out of the magazine well. The second lever is spring biased to position a spur extending therefrom into the path of a trigger bar. An end of the second lever is connected to the first lever via the floating pin. In the absence of the magazine from the magazine well the first lever will rotate into the magazine well, thereby permitting the second lever to rotate and position the spur in the path of the trigger bar to prevent discharge of the firearm.

Abstract: A trigger return spring assembly mountable on a frame of a firearm includes a trigger mounted on the frame pivoting about a first axis of rotation. A trigger bar attached to the trigger pivots relative to the trigger about a second axis of rotation fixed on the trigger. A bore extends through the trigger along a third axis oriented transversely to and positioned between the first and second axes of rotation. A plunger extends through the bore and is movable along the third axis. A first end of the plunger is attached to the trigger bar and a second end has a retaining surface oriented transversely to the third axis. A shoulder is positioned within the bore proximate to the trigger bar. A compression spring captured within the bore, between the shoulder and the retaining surface, exerts a force pushing the retaining surface away from the shoulder.

Abstract: A mounting mechanism has a base upon which a rotating cam is mounted. The cam has a lobe which extends beyond the perimeter of the base when the cam is in a first position and remains within the perimeter of the base when the cam is in a second position. A detent is used to lock the cam in the first position. The detent includes a leaf spring positioned on the cam which defines a kink. The kink is engageable within a niche in the base when the cam is in the first position. An accessory attached to the mounting mechanism may be attached to a structure using the mounting mechanism. The base fits within a slot in the structure and the lobe of the cam engages the structure when the cam is in the first position to lock the mounting mechanism and the accessory to the structure.

Abstract: A grip strap is removably attachable to a grip of a firearm using a plunger mounted in the grip and biased by a mainspring which also biases a hammer strut of the firearm.

Abstract: A reflex sight for a firearm has an optical element received within a receptacle of a housing. The housing is mounted on the firearm. Shoulders extending from a base of the optical element engage corresponding shoulders extending from the housing into the receptacle to position the optical element so that it intersects a line of sight parallel to but offset from the firing axis of the firearm. The optical element includes a collimating reflector which produces a virtual reticle visible when viewed along the line of sight when aiming the firearm. The optical element is captured within the receptacle between the firearm or a plate and the shoulders of the housing.

Abstract: An extractor for a semiautomatic firearm has an elongated strap with a hook at one end and a projection at an opposite end. The hook engages the rim of a chambered cartridge and the projection is received within a recess in the slide. A notch in the strap engages a pin in the slide to retain the extractor. One end of a leg is attached to the strap near the hook, the opposite end of the leg engages the slide. The leg acts as a biasing spring to bias the hook into engagement with the cartridge.

Abstract: A safety for a firearm has a blocking lever with an arresting lobe that engages a plunger. The arresting lobe and plunger are statically counterbalanced about a pivot axis by a counterbalance lobe on the blocking lever. The blocking lever is movable between a safe position, where it engages and prevents motion of a firing element, and a fire position, where it cannot engage the firing element. A cam, moved by the trigger, moves the plunger, which moves the blocking lever from the safe to the fire position to permit discharge of the firearm upon further pull of the trigger.

Abstract: A mounting mechanism has a base upon which a rotating cam is mounted. The cam has a lobe which extends beyond the perimeter of the base when the cam is in a first position and remains within the perimeter of the base when the cam is in a second position. A detent is used to lock the cam in the first position. The detent includes a leaf spring positioned on the cam which defines a kink. The kink is engageable within a niche in the base when the cam is in the first position. An accessory attached to the mounting mechanism may be attached to a structure using the mounting mechanism. The base fits within a slot in the structure and the lobe of the cam engages the structure when the cam is in the first position to lock the mounting mechanism and the accessory to the structure.

Abstract: A magazine safety for a semiautomatic firearm uses two levers connected via a floating pin. The first lever is pivotable into and out of the magazine well. The second lever is spring biased to position a spur extending therefrom into the path of a trigger bar. An end of the second lever is connected to the first lever via the floating pin. In the absence of the magazine from the magazine well the first lever will rotate into the magazine well, thereby permitting the second lever to rotate and position the spur in the path of the trigger bar to prevent discharge of the firearm.

Abstract: An extractor for a semiautomatic firearm has an elongated strap with a hook at one end and a projection at an opposite end. The hook engages the rim of a chambered cartridge and the projection is received within a recess in the slide. A notch in the strap engages a pin in the slide to retain the extractor. One end of a leg is attached to the strap near the hook, the opposite end of the leg engages the slide. The leg acts as a biasing spring to bias the hook into engagement with the cartridge.

Abstract: A reflex sight for a firearm has an optical element received within a receptacle of a housing. The housing is mounted on the firearm. Shoulders extending from a base of the optical element engage corresponding shoulders extending from the housing into the receptacle to position the optical element so that it intersects a line of sight parallel to but offset from the firing axis of the firearm. The optical element includes a collimating reflector which produces a virtual reticle visible when viewed along the line of sight when aiming the firearm. The optical element is captured within the receptacle between the firearm or a plate and the shoulders of the housing.