Jul 28, 2026

US12693083 - Bolt assembly for firearm

A modular two-piece bolt system for firearms with blowback actions provides a rear bolt piece which detachably couples to plural different front bolt pieces each of different mass. The front bolt pieces have a similar configuration and common coupling interface which forms an interlocked relationship with a complementary configured coupling interface on the rear bolt piece to prevent axial separation of the pieces when the action of the firearm is cycled. The system allows various front bolt pieces to be selected and used interchangeably with the rear bolt piece so that a front bolt piece of proper mass can be matched to the energy of ammunition to be fired. The front and rear bolt pieces when coupled define a continuous extended longitudinal passage which receives the rear breech end portion of the firearm barrel therethrough to reduce the projected length of the barrel.

Inventors: Frank J. Saunders, Jr., Reed Matthew Hubbell, Benjamin Gerard Hawkins
Filing date: 2025-05-20

firearmboltassemblyblowback

The patent describes a modular two-piece bolt assembly for firearms that allows interchangeable front bolt pieces of varying mass to be used with a common rear bolt piece, enhancing adaptability to different ammunition types. This design minimizes the overall length of the firearm by allowing the rear breech end of the barrel to pass through the coupled bolt assembly.

Claim 1

1 . A modular bolt assembly system for a firearm with blowback operating system comprising: a longitudinal axis; a first front bolt piece having a first mass and internally comprising a first longitudinal passage coaxial with the longitudinal axis, the first longitudinal passage being configured to receive a rear portion of a first firearm barrel chambered for a first cartridge; a second front bolt piece having a second mass different than the first mass, the second front bolt piece internally comprising a second longitudinal passage coaxial with the longitudinal axis, the second longitudinal passage being configured to receive a rear portion of a second firearm barrel chambered for a second cartridge having a propellant powder charge with energy different than the first cartridge; a rear bolt piece internally comprising a third longitudinal passage coaxial with the longitudinal axis, the third longitudinal passage comprising a breech face and being configured to receive the rear portions of the first or second firearm barrel; wherein the first and second front bolt pieces each have a common first coupling interface configured to mate with a corresponding complementary configured second coupling interface formed on the rear bolt piece; wherein the rear bolt piece is detachably coupleable to the first or second front bolt piece to form a mechanical interlock which prevents separation thereof in a direction along the longitudinal axis. a longitudinal axis; a first front bolt piece having a first mass and internally comprising a first longitudinal passage coaxial with the longitudinal axis, the first longitudinal passage being configured to receive a rear portion of a first firearm barrel chambered for a first cartridge; a second front bolt piece having a second mass different than the first mass, the second front bolt piece internally comprising a second longitudinal passage coaxial with the longitudinal axis, the second longitudinal passage being configured to receive a rear portion of a second firearm barrel chambered for a second cartridge having a propellant powder charge with energy different than the first cartridge; a rear bolt piece internally comprising a third longitudinal passage coaxial with the longitudinal axis, the third longitudinal passage comprising a breech face and being configured to receive the rear portions of the first or second firearm barrel; wherein the first and second front bolt pieces each have a common first coupling interface configured to mate with a corresponding complementary configured second coupling interface formed on the rear bolt piece; wherein the rear bolt piece is detachably coupleable to the first or second front bolt piece to form a mechanical interlock which prevents separation thereof in a direction along the longitudinal axis.

Google Patents

https://patents.google.com/patent/US12693083

USPTO PDF

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/12693083