The frame is an SB2, good for 270win pressures and case head thrust, that puts it good up to and including the 460S&W in my book since that's what mines gonna be soon!!
Wayne York has done several to Casull which are doing fine, the loads that I've shot in mine so far are Ruger 45 Colt loads from Hodgdon, in fact I went 1gr over with lil'gun cuz I'm using a longer COL and 250gr XTP data, 1.673" with the Speer bullet, 1.941" with the SST, same data.
Tim