I have a Super Blackhawk with a S47B frame. I confirmed with Sturm Ruger this piece has a brass frame and is a 3 screw model and was shipped from the factory in June 1971. The barrel length is 7 1/2" and has a polychoke vented rib on it. I had been told but again the factory did not verify that a few of these revolvers with the Polychoke rib were sent directly to Polychoke factory. Does anyone out there know more about this particular feature? MoFrank :?: