Is it possible to duplicate the ballistics of the 338 Excaliber with the 338-378 Weatherby,say 3060fps. with a 250 grain bullet to 3250 fps. of the 338 Excaliber or is there just not enough case capacity in the weatherby case.

Near as I can tell, the Weatherby and Rigby (Excaliebr parent) are the same case, one with belt, which to me says same capacity.