[armed85]

I used a bronze brush to clean up a blued gun. That brown/red color that it leaves behind on the surface of the metal usually wipes off with oil, but for some reason I can't get it off of a part.

The part in question is a slide release.

Any tips?

I'm thinking copper bore solvent will do the trick. What works for copper might work for bronze no?

[The Bushmaster]

Yes...Don't use a bronze brush...Use, instead, an old tooth brush...For your present problem try copper solvent like Hoppe's Benchrest #9...