I'm pretty sure that the finish is original. This gun has had 2 previous owners, I am positive the second never altered the gun and am almost as sure the original owner didn't either. There is no trace of anodizing inside or out, even in the nooks and crannies, so I g uess I dont know. It does appear to have a coating of some sort as there is a very minor blemish on the underside of the trigger guard...