Patent ID: 8341863

Claim:
Barrel holder for a drop-down barrel weapon comprising: at least one tapped hole, an interchangeable barrel including a corresponding thread to screw into the tapped hole, the barrel holder further including a ring shoulder receiving space between the tapped hole and a cartridge insertion end of the barrel holder for receiving a ring shoulder adapted to support an edge of a cartridge, and a circumferential ring shoulder positioned in the ring shoulder receiving space; wherein the circumferential ring shoulder comprises a first arc section and a second arc section, the first arc section being formed from an interchangeable, axially movable cartridge extractor positioned in a retracted position, the axially movable cartridge extractor being movable between the retracted position and an extended position, the circumferential ring shoulder corresponding to the caliber of the interchangeable barrel, and the second arc section of the ring shoulder being formed by an interchangeable adapter part corresponding to the caliber of the interchangeable barrel, the interchangeable adapter part being sandwiched between the interchangeable barrel and a shoulder formed in the cartridge insertion end of the barrel holder, wherein the interchangeable adapter part comprises an inner curved surface shaped and sized to abut a portion of an outermost diameter of an edge of a cartridge to be accommodated in the interchangeable barrel, the adapter part being a separate removable and replaceable component part from the interchangeable barrel, and wherein the axially movable cartridge extractor has an inner curved surface having the same radius of curvature as the inner curved surface of the adapter part and sized to abut a remaining portion of an outermost diameter of an edge of a cartridge to be accommodated in the interchangeable barrel.