It is indeed a USFA gun and one made from all USA sourced parts. It is one of their "Gunslinger" models, which were deliberately aged to look like vintage pistols. That is the correct serial number range (58,000). I know this because I have two of them, a BP framed 7-1/2" 45 Colt and a smokeless framed 4-3/4" 38 Colt and Smith & Wesson Special.
I was told they have an actual applied finish. They were not just left in the white to rust. The ones I have show very little sign of handling or holster wear. When I first heard about them I thought it was a terrible idea. After I saw the 7-1/2" I have I became a believer.
Oh and by the way, I absolutely hate the Gunslinger name. YUCK!
Dave