I have a 44 magnum revolver with a 6.5" barrel and a 10" Contender barrel and the Contender barrel sends the same hunting loads 300fps faster than the revolver.
I don't know how this translates to Casull, but I'll bet it's at least a 300fps difference. The 300fps increase for the 44 makes the Contender in a 44 magnum comparable to a 454 in a revolver.