Reduced-energy cartridge with exterior sealing member for fluted chamber

A method of manufacturing a reduced-energy cartridge for a chamber of a firearm, the method comprising:

• attaching a first end of a sabot to a case to cooperatively define an internal combustion chamber with the case, including moveably attaching the sabot to the case and supporting the sabot for movement relative to the case from an unfired position to a fired position, the sabot including a second end that is separated from the first end along a longitudinal axis, the second end extending from the case along the longitudinal axis to define an exterior surface of the cartridge for facing the chamber in the unfired and fired positions, the exterior surface including a datum taper with a taper end, the datum taper tapering downward in radius as the datum taper extends in a forward direction along the longitudinal axis from the taper end toward the second end;
• and
• providing a sealing member on the second end of the sabot to partly define the exterior surface, the sealing member projecting radially outward from the longitudinal axis and radially outward from the sabot, the sealing member defining a blowback boundary where the cartridge is configured to seal against an inner surface of the chamber of the firearm, a forward area of the cartridge and a rear area of the cartridge being separated by the blowback boundary, the sealing member configured for releasably sealing against the inner surface of the chamber to regulate pressure at the forward area resulting from combustion within the combustion chamber,
• the sealing member being disposed at least partly in the forward direction from the datum taper, the sealing member having an outer radius that is greater than that of the datum taper at the taper end.

A reduced-energy cartridge for a chamber of a firearm comprising:

• a case;
• a sabot including a first end and a second end that are separated along a longitudinal axis, the sabot including a combustion passage extending longitudinally between the first end and the second end, the first end attached to the case to cooperatively define an internal combustion chamber with the case, the first end supported for movement relative to the case from an unfired position to a fired position resulting from combustion within the combustion chamber, the second end extending from the case along the longitudinal axis to define an exterior surface of the cartridge for facing the chamber in the unfired and fired positions, the second end having a frustoconic datum taper with a taper end, the datum taper tapering downward in radius as the datum taper extends in a forward direction along the longitudinal axis from the taper end toward the second end;
• and
• a sealing member that is provided on the second end to partly define the exterior surface, the sealing member projecting radially outward from the longitudinal axis and radially outward from the sabot, the sealing member being resiliently flexible to define a blowback boundary where the cartridge is configured to resiliently flex and seal against an inner surface of the chamber of the firearm, a forward area of the cartridge and a rear area of the cartridge being separated by the blowback boundary, the sealing member configured for resiliently flexing to releasably seal against the inner surface of the chamber to regulate pressure at the forward area resulting from combustion within the combustion chamber, the sealing member being disposed in the forward direction and spaced apart at a distance from the datum taper with respect to the longitudinal axis, the sealing member having an outer radius that is greater than that of the datum taper at the taper end.