A load I shoot for fun in my Triumph is a 300gr for the 45-70, under 70gr of 2F Goex. Very accurate, under 1" at 100yds, very little recoil. I have not used it on game, because of it being a rifle bullet. But say a 300gr xtp, with a similar load would do the trick.

I have to agree a heavier bullet, moving slower, would be good to go out to 50yards!