Owner of Buffalo Bore Tim Sundles on 454 Casull Ammunition:
The .454 Casull is one cartridge that Buffalo Bore Ammunition does not load to it's full pressure limit. When loaded to it's full pressure potential the .454 Casull can become unreliable and unpleasant to shoot. At upper pressure levels, heavy bullets tend to jump crimp - tying up the cylinder. (wouldn't this be great in an emergency) Also, fired brass can stick in the chambers.
Buffalo Bore Ammunition feels that a 300 gr. bullet at 1650 fps is still very powerful, comfortable to shoot, and TOTALLY RELIABLE. At these levels, these bullets give up nothing in performance