Yes - Jeremy has a point - cast will usually give 100fps higher speed with the same load as for a jacketed bullet. It was for that reason, Elmer suggested I use full power loads with the bluff-nosed Lyman 560gr. in my .458 2" for Africa. With them, I could get 1,950fps.

I would think a 500gr. from the double shotgun action would be maxed out in the 1,600fps to 1,800fps range, depending on the case used.