It is TRULY AMAZING to see this topic again---and---again---and again.
BOTTOM LINE: Steel wool will remove rust. Bluing is rust---also known as black oxide. Steel wool removes bluing---every time----all the time.
Bronze wool does not remove bluing.
As an aside-----Kleen Bore makes a bronze "toothbrush", for lack of a better description, which will most certainly remove rust from pitting. As another aside, it will also remove "firing residue" (lead and powder residue) from the front face of the cylinder and rear face of the barrel----and from the little nooks and crannies between the rear of the barrel. If you have even a modicum of imagination, you should, right about now, be starting to think maybe some of those "unfired" guns we see now and then are really guns which have been cleaned by someone who KNOWS what they're doing.
Last Bottom Line: Bronze wool/toothbrushes work best in concert with a light oil.
Ralph Tremaine