When I clean my rifle, I use copper solvent and a brass brush then pull patches through it until they stop coming back with a bluish residue. (or at least almost, I can never get them to come back completely white no matter how long I take on it.) How detrimental is copper residue to accuracy? I also have cleaned my pistols (Glock 27 and Kahr PM 40) with copper solvent but I never seem to get any bluish tint at all on my patches. Why? Do pistols not pick up copper as bad as rifles?