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US 8,572,875 B2Granted
Bolt-hold open apparatus
OwnerChase B. Sisgoldinventor
Life of this patent
Estimating the term…
Abstract
A firearm-magazine interface for replacing an existing firearm-magazine interface of many existing firearms such as assault rifles, namely AK series (AK74, AK47, etc.) provides a lock that holds open the bolt after a last round is fired from a magazine. The firearm-magazine interface also includes a single-button magazine eject. After firing the last round, a bolt-hold lock is urged upwardly in the path of the returning bolt and catches a face of the bolt, thereby locking the bolt open until the magazine is replaced with a replacement magazine, at which time a bolt-hold release paddle pulls the bolt-hold lock downwardly, releasing the bolt to chamber a first round from the replacement magazine.
Claims20
A firearm-magazine interface for a firearm having a spring-loaded bolt and a receiver cross-member pin, the receiver cross-member pin located in the vicinity of a magazine opening of the firearm, the firearm-magazine interface comprising:
- a magazine frame for receiving a magazine, the magazine frame mountable to the firearm at the magazine opening;
- a bolt-hold lock, the bolt-hold lock slideably interfaced to the magazine frame, a follower contact ledge of the bolt-hold lock interfaceable with a magazine follower of the magazine, the bolt-hold lock has a retracted position in which a spring-loaded bolt of the firearm freely passes by the bolt-hold lock and the bolt-hold lock has an extended position, such that when the magazine is empty, the magazine follower pushes on the follower contact ledge and the follower contact ledge lifts the bold-hold lock into the extended position, thereby a bolt catch edge of the bold-hold lock is positioned to engage with a face of the spring-loaded bolt to hold the spring-loaded bolt in an open position after a last round is fired from the magazine;
- a bolt release lever is moveably interfaced to the magazine frame;
- and
- a bolt-hold release paddle affixed to the bolt release lever, whereas activation of the bolt-hold release paddle rotates the bolt release lever and urges the bolt-hold lock from the extended position to the retracted position, away from the face of the spring-loaded bolt, thereby adapted to release the spring-loaded bolt;
- whereas the bolt-hold lock is adapted to brace against the receiver cross-member pin of the firearm, providing support to counter a force exerted by the spring-loaded bolt.
3 more elements
A firearm-magazine interface for a firearm having a bolt for chambering rounds of ammunition, a chamber and a receiver cross-member pin, the receiver cross-member pin located in the vicinity of a magazine opening of the firearm, the firearm-magazine interface comprising:
- a magazine frame for receiving a magazine, the magazine frame adapted to be fastened to the firearm at the magazine opening;
- a bolt-hold lock, the bolt-hold lock is slideably interfaced to and held by the magazine frame, the bolt-hold lock is configured to brace against the receiver cross-member pin, providing support to counter a force exerted by the bolt, a first area of the bolt-hold lock has an angled forward edge on a side of the bolt-hold lock closest to the chamber of the firearm, the first area of the bolt-hold lock has an opposing substantially flat bolt catch edge on a side of the bolt-hold lock distal from the chamber, the bolt-catch edge being substantially perpendicular to a path of travel of the bolt, the first area of the bolt-hold lock also having a follower contact ledge, a distal second area of the bolt-hold lock having a bolt-hold lock pin;
- the follower contact ledge of the bolt-hold lock is interfaceable with a magazine follower of the magazine;
- a bolt release lever is rotatably interfaced to the magazine frame and the a first end of the bolt release lever interfaces to the bolt-hold lock pin;
- a bolt-hold lock return spring urges the bolt release lever such that the bolt-hold lock is biased away from the path of travel of the bolt;
- and
- a bolt-hold release paddle, the bolt-hold release paddle is affixed to a second end of the bolt release lever;
- whereas after a last round of the magazine is chambered, the follower contact ledge is adapted to be pushed by the magazine follower of the magazine and thereby urges the bolt-hold lock into the path of travel of the bolt and after firing of the last round, the angled forward edge of the bolt-hold lock is adapted to be pushed by a leading edge surface of the bolt to momentarily displace the bolt-hold lock out of the path of travel of the bolt and after the bolt passes the bolt-hold lock, the bolt-hold lock is adapted to return into the path of travel of the bolt such that, the bolt is held open by the bolt catch edge of the bolt-hold lock;
- whereas pressing of the bolt-hold release paddle after the bolt is held open by the bolt-hold lock urges the bolt-hold lock away from the bolt, thereby releasing the bolt towards the chamber.
6 more elements
A firearm-magazine interface for a firearm having a bolt for chambering rounds of ammunition, a chamber and a receiver cross-member pin, the receiver cross-member pin located in the vicinity of a magazine opening of the firearm, the firearm-magazine interface comprising:
- a magazine frame for receiving a magazine, the magazine frame fastenable to the firearm at the magazine opening;
- a bolt-hold lock, the bolt-hold lock is slideably interfaced to and held by the magazine frame, the bolt-hold lock is configured to brace against the receiver cross-member pin, providing support to counter a force exerted by the bolt, a first area of the bolt-hold lock has an angled forward edge on a side of the bolt-hold lock that is closest to the chamber of the firearm, the first area of the bolt-hold lock has a substantially flat bolt-catch edge on a side of the bolt-hold lock that is distal from the chamber, the bolt-catch edge is substantially perpendicular to a path of travel of the bolt, the bolt-hold lock has a follower contact ledge that interfaces with a magazine follower of the magazine, a distal second area of the bolt-hold lock has a bolt-hold lock pin;
- a release lever is pivotally interfaced to the magazine frame, a first end of the release lever interfaces to the bolt-hold lock pin and a second, distal end of the release lever interfaces to a bolt-hold release paddle, the bolt-hold release paddle is movably mounted on a first side of the magazine frame;
- a bolt-hold lock return spring is interfaced between the magazine frame and the release lever, the bolt-hold lock return spring urges the release lever in a direction that biases the bolt-hold lock away from the path of travel of the bolt;
- and
- a magazine release button is movably affixed to a second opposing side of the magazine frame, the magazine release button is urged outwardly from the magazine frame by a magazine catch spring, the magazine release button is mechanically interfaced to a magazine catch;
- whereas after a last round of the magazine is chambered, the magazine follower of the magazine urges the bolt-hold lock into the path of travel of the bolt and after firing of the last round, an angled leading surface pushes against the angled forward edge of the bolt, momentarily displacing the bolt-hold lock out of the path of travel of the bolt, and after the bolt passes the bolt-hold lock, the bolt-hold lock returns into the path of travel of the bolt and the face of the bolt pushes against the bolt catch edge of the bolt-hold lock and the bolt is held open by the bolt-hold lock;
- whereas pressing of the bolt-hold release paddle after the bolt is held open by the bolt-hold lock urges the bolt-hold lock away from the bolt, thereby releasing the bolt towards the chamber;
- whereas pressing of the magazine release button moves the magazine catch outwardly away from the magazine frame for releasing the magazine from the magazine frame.
6 more elements
Dependencies are inferred from the claim text.