BCC, I have CRS (Cant remember stuff) lol. Salt bluing is a darker black color and rust blue is a grayer blue color but what I am seeing now doing my own salt bluing is the higher polish you put on the metal, the bluer the salt blue looks in some light at least on a couple of commercial looking High polish P.38s. Yes, rust blue certainly is more resistant to wear and that would explain the sideplate and muzzle side wear you spoke of. I am still learning and doing so, I keep asking these puzzling questions as you have. I wish I had some examples to look at, that would help me make up my mind. Thor
Ted's Luger Strawing Service