It's a very old re-finish that almost looks historic if you don't know that this revolver can't have been blued. The .38 Special stamping is actually unusual since the vast majority of converted BSR's did not receive any additional markings indicating the caliber conversion.

Just the caliber stamp alone in that location should have been the figurative equivalent of bonking that gunsmith in the nose with a baseball bat as to the originality of that barrel. So I'm officially withdrawing my "no disrespect to your gunsmith intended" from my first post .