Breech lock, especially for hand firearms

A breech mechanism, comprising:

• a breech piston for pushing a cartridge into a cartridge chamber, said breech piston comprising two radially projecting bolt elements;
• a breech casing having a breech piston bore extending therein, a longitudinal groove for each of said bolt elements of said breech piston extending along said breech piston bore, and an annular space communicating with said longitudinal grooves and said breech piston bore, said annular space being partially defined by a rear support surface on said breech casing;
• a member having an annular space conical contact surface, said annular space conical contact surface further partially defining said annular space;
• a breech sleeve rotatably disposed in said annular space of said breech casing so as to be rotatable between an open feed position and a locked end position, said breech sleeve comprising a breech sleeve groove for each of said longitudinal grooves of said breech casing in alignment with said longitudinal grooves in said open feed position and a breech sleeve conical contact surface adjacent to said annular space conical contact surface;
• and
• a conical sealing sleeve between said conical contact surfaces of said annular space and said breech sleeve;
• wherein said breech casing has at least one gas exit opening therein communicating with said annular space.