Forgive my ignorance, but are all of the refinishing options available out there primarily cosmetic (understanding that bluing, nickel plating, cerakote, etc., all convey SOME sort of protection to the underlying substrate) or will any of them cover/fill/repair or prevent scratches or wear on mating/wearing surfaces? I'm thinking scratches on frames from safeties/decockers, slide/frame rail wear, wear on top of barrel/bottom surface of slide hood; things like that. Yes, yes, proper lubrication I know, but sometimes you can get a used gun with some wear and I want to know if any refinishing options can "rebuild" lightly scored surfaces.