Hello my friend
I wonder myself. Do you mean externally or internally?
My experience:
Flitz metal polish--works good, lots of work. Polishes.
Birchwood-Casey Lead Away cloths--the absolute best thing for stainless cylinder faces that are black with lead and carbon. Nothing removes lead/carbon from s/s gun surfaces better, IMHO. Not to be used on blued steel.
Breakfree CLP--degrease and then wipe down with this for best rust protection.
75% Mobil One, 25% Auto Trans Fluid (Dexron)--I made this one up myself. Let it sit on your gun for as long as you care to be patient. It just takes a thin layer. When you wipe it off, it will remove all but the most stubborn residue and leave a shiny surface.
Always apply with cloth, never paper.
Regards,
Ledbetter