If you have found a load that shoots well at 20:1 don't change it until after your hunt (at the earliest). If you want to refine the load using different alloys then, knock yourself out. If you cast your own it is easy to cast 10, 20 or 30 each of different alloys to take to the range. If you buy them from someplace, it can get spendy to try different alloys.
I do cast my own and early on, tried 20:1, 25:1, 30:1, 35:1 and 40:1 alloys. I had some (not much) leading with the 20:1 and 25:1 bullets. 30:1 was leading free for my rifle(s) so I stuck with that, occasionally I still use 40:1. When you cast your own, and make your own alloys and you are as cheap as I
CAN be, the more lead in the alloy vs the tin in your alloy, the less $ they cost per bullet . . . but maybe that's just me
.
BTW - good luck on your hunt. A 45-70 will punch a hole clear through an elk. I know it did on a buffalo.
