I've used a .54 Hawken that I built for elk hunting in CO and the load is .535 RB, .018 patch and 120 grs 3f. The bbl twist is 1:66 and this load is very accurate.
The last elk shot w/ this rifle was at 107 paces and went 40 yds after the shot. My paces are that of a 6'-2" man.
Many have asked why such a "big load"? It's not because of the killing power, it's because of the distances encountered in CO. The other reason is the low mid-range height....some of the other elk shot w/ this rifle were somewhere around mid-range and the same hold was used, which in the heat of battle, is important.
The recoil, anyways to me, is moderate, but some might find it causes flinching. My son who now has the rifle has no problem w/ the recoil and has shot deer and elk w/ it.....Fred