I have both the .44 Mag. and the .454 Casull in the Ruger Super Redhawk. With high performance loads the .454 has substantially much harder recoil. I'm talking heavy bullets with maximum powder charges, like what's avaliable from Buffalo Bore and Cor-Bon.
The original Triplex loads that were developed by Dick Casull back in the early 70's were unbelievable when compared to today's high performance loads. They were also very dangerous.
Dick Casull blew up many .45 caliber revolvers back in the day, striving for that extra bit of performance out of his guns. Today, with guns like the Ruger Super Redhawk, and customs from Hamilton Bowen, along with the high grade Freedom Arms guns built in this caliber, strength is much higher than on the .45 caliber conversions Casull was using when developing these loads.