主权项 |
1. A breech assembly for a gun having a barrel comprising:
a barrel extension aligned with and extending rearwardly from the barrel, said barrel extension having a radially inwardly annular abutment surface adjacent a rear end of the barrel extension, an elongated bolt axially slidably movable between a loading position in which a cartridge is loaded between the bolt and the barrel extension, and a firing position in which the cartridge is loaded into the barrel extension and the bolt extends into the barrel extension and abuts against the cartridge, an elongated expandable mandrel mounted to said bolt so that said mandrel surrounds at of least a portion of said bolt, an expansion pin slidably mounted on said bolt and movable between a retracted position in which said mandrel collapses on said bolt to allow the removal of said bolt from said barrel extension, and a position in which at least a portion of said expansion pin is inserted into said mandrel and deflects said mandrel outwardly so that a rear end of said mandrel abuts against said abutment surface in said barrel extension to thereby lock said bolt to said barrel extension. |