Patent ID: 8109193

Claim:
A kit for modifying a bolt carrier group actuating apparatus of a firearm, comprising: a gas block interface portion; and a gas expansion assembly including an expansion body and a piston, wherein an expansion body passage extends through the expansion body between opposing end portions thereof, wherein the expansion body is configured for allowing the piston to be accessible through a first one of said end portions thereof, wherein the piston is slideably engaged within the expansion body passage for forming a gas expansion chamber within the expansion body passage between the piston and a second one of said opposing end portions of the expansion body, wherein the gas block interface portion is attached to the second one of said opposing end portions of the expansion body such that a gas routing passage of the gas block interface portion is coupled to a corresponding gas routing passage extending through an end face of the expansion body at the second one of said end portions thereof thereby allowing combustion gases to flow through said gas routing passages, wherein the gas block interface portion is engagable with an as-manufactured gas routing passage of an original equipment manufacturer (OEM) gas block of the firearm for allowing combustion gases from the OEM gas block to be routed therethrough into the gas expansion chamber through the gas routing passage within the end face at the second one of said end portions of the expansion body, wherein the gas block interface portion is configured whereby such attachment of the expansion body with the gas block interface portion precludes relative displacement of the gas block interface portion toward the gas expansion chamber; wherein the piston includes opposing end faces, wherein a first one of said opposing end faces is exposed within the gas expansion chamber, wherein a second one of said opposing end faces is disposed outside of the gas expansion chamber and serves as a surface through which the piston is coupled to an operating rod, and wherein a centerline longitudinal axis of the gas block interface portion is offset with respect to a centerline longitudinal axis extending through the second one of said opposing end faces.