Designed for problem barrels or high volume shooters where copper buildup is a problem. Copper Killer 50 B.M.G. is the best solvent for removing stubborn copper deposits. Copper Killer 50 B.M.G. is the industrial strength copper remover that quickly tackles the toughest jobs. Completely barrel safe and contains no acids, amines or chlorides. Rated the #1 copper remover by Gun Test Magazine.