Patent ID: 7984668

Claim:
A two-piece, two-stage, reduced energy mechanically-operating cartridge for launching a projectile from a firearm, comprising: a piston sleeve comprising a piston sleeve jacket having a jacket wall and defining a projectile cavity at a first longitudinal end for coupling the projectile therein and a second longitudinal end for coupling with a primary case, a sealing surface on the jacket wall proximate to the first longitudinal end, and a circumferentially extending recess in the jacket wall proximate to the second longitudinal end, wherein the thickness of the jacket wall at the sealing surface is greater than the thickness of the jacket wall at the recess; the primary case comprising a primary case jacket for being axially coupled with the second longitudinal end of the piston sleeve and defining a primary case cavity for coupling with a propellant mechanism, wherein the primary case is slidable within the piston sleeve between a compressed and a telescoped position such that the primary case extends from the primary case jacket when in the telescoped position; and an o-ring disposed between the piston sleeve and the primary case for sealingly engaging the piston sleeve with the primary case and is positioned against the sealing surface when in the compressed position, wherein the recess is adapted to nonsealingly receive the o-ring when the primary case is slid into the telescoped position.