Patent ID: 7779743

Claim:
A kit for modifying a bolt carrier group actuating apparatus of a firearm configured by its original manufacturer to have a gas-driven bolt carrier, comprising: a gas expansion assembly having an end portion thereof engagable with an as-manufactured original equipment manufacturer (OEM) gas block of a firearm and having a passage extending through said end portion for routing combustion gases from the as-manufactured OEM gas block into a gas expansion chamber of the gas expansion assembly thereby allowing expansion of said gases therein for generating a bolt carrier driving force; an operating rod driven bolt carrier including an operating rod engaging lug, wherein the operating rod driven bolt carrier is configured for being operably engaged within an as-manufactured OEM receiver body of the firearm with the operating rod engaging lug located in a gas tube lug receiving portion of the as-manufactured OEM receiver body; an operating rod engagable between the gas expansion assembly and the operating rod engaging lug for exerting the bolt carrier driving force on the operating rod engaging lug; the gas expansion assembly includes a gas spigot and a gas expansion device; the gas expansion device including an expansion body and a piston; the gas spigot includes a gas block interface portion, a gas expansion device interface portion and a passage extending therebetween; the expansion body includes a passage extending between opposing end portions thereof; the piston is slideably engagable within the expansion body passage through one of said opposing end portions for forming a gas expansion chamber within the expansion body passage between the piston and gas spigot and such that the expansion body and the piston define respective opposing end portions of the gas expansion device; the gas expansion device interface portion of the gas spigot is engagable with a first one of said end portions of the gas expansion device in a manner whereby the gas spigot passage is communicatively coupled to the gas expansion chamber; the gas block interface portion engagable with the as-manufactured OEM gas block; the first one of said end portions of the gas expansion device includes an end portion of the piston; and the piston includes a gas routing passage extending therethrough for allowing said combustion gases to be routed from the gas spigot through the piston into the gas expansion chamber.