In proof or out of proof is more a question for our British posters. So if it is .001-.003 thousands out of proof it only matter if you are trying to sell it where proof laws are accepted and enforced, which is not in the US. The real question that you have already answered is is it safe to shoot. The barrels are clean, with no pitting and have good thickness. You understand what a proper diet shell wise this gun should be getting. So you should be good to go. And I agree that is a very fine looking gun.
