Patent ID: 8042296

Claim:
A semiautomatic or fully automatic firearm comprising: a barrel comprising a rear barrel end forming a cartridge chamber configured to receive a projectile from a rear of the cartridge chamber; a breech guide comprising a rear wall and a breech body positioned in the breech guide between the cartridge chamber and the rear wall such that the breech body moves in a longitudinal direction between an open position, which releases the cartridge chamber in order to load the projectile, and a closed position which closes the cartridge chamber, wherein in the closed position the breech body closes the cartridge chamber at the rear of the cartridge chamber and is configured to be an opposing bearing for the cartridge chamber; at least one permanent magnet positioned and configured such that, at least in the closed position and in positions close to the closed position, a magnetic force of the at least one permanent magnet urges the breech body to the closed position, such that the magnetic force of the at least one permanent magnet simulates a higher mass of the breech body, the breech body acting as an opposing carrier during the firing of the projectile; and a second permanent magnet positioned to attract the at least one permanent magnet and positioned so as rotate relative to one another about a center axis aligned with an axial bore axis of the barrel, wherein the at least one permanent magnet and the second permanent magnet are rotatable relative to one another between a first rotation angle position in which a north pole is aligned with a south pole and a second rotation angle position in which the north pole is not aligned or less aligned with the south pole, such that the magnetic force between the poles can be reduced by rotation.