My normal 454 Casull load is 8gr of Bullseye under a 250gr Hornady XTP. This should run right about 1,000 fps in a 7.5" barrel, but I have no chronograph to measure it. My Model 83 came with a 454 Casull load sheet that list quite a few loads from .45 Colt level, all the way to 240gr bullets at over 2,000 fps. I have also tried 265gr Cast Performance cast bullets over 13 and 14gr of Unique, this load generates about the same energy as a .44 Magnum. The .454 Casull is a very versatile caliber. I bought the .45 Colt cylinder with mine, but never use it, as I can do anything I want in 454 Casull brass. If you load down, you will more than likely need a taller front sight blade, I did. Otherwise your shots will hit pretty high, even with the rear sight adjusted all the way down. I don't find full power 454's to be that fun to shoot, but the revolver is quite nice to shoot at lower power levels. My next project for this revolver is the Lyman 452424 255gr Keith bullet at 1,200fps or so.
Jared