I scratched the hell out of the trigger guard. I was going to cold blue it and then I thought, is this thing actually blued or is it some sort of coating? So can anyone tell me what I should touch up the finish on my 627 with for it to match the original finish? Thanks

If you have the black pc 627 you will have to use alumihyde from brownells. They also have other simular finishes to use.

The "6" series guns are stainless steel and regular bluing doesn't take on stainless. Not sure what kind of finish SW uses to black up stainless, I think SIG calls their "nitron" or something like that.