The 454 Casull gives a 300 grn bullets about 1700 fps.
That's quite a bit slower than most 50 cal muzzel loaders shooting a 300 grn projectile.
Are you sure about that? I think real world velocity on a typical 80-100 grain 777 load under a 300 gn xtp (very typical load) would be right around that 1700, plus or minus a little.
Yeah? Nea?