Abstract: A self-cleaning gas operating system for a firearm having a conventional bolt carrier assembly is disclosed comprising: a nozzle assembly having a nozzle in direct communication with a port on the muzzle; said nozzle assembly nested within a piston cup having a vent, a connecting rod operationally linking the piston cup to a spring loaded operating rod which is substantially co-axial to a bolt carrier key having a striking portion, said striking portion having a concave strike face in contact with said operating rod, wherein gas discharged from a fired cartridge displaces the piston cup and causes the operating rod to strike the strike face displacing the bolt assembly.