Back to basic .458 WM loads with 350-gr Speer "tough enough" bullet as previously suggested, power enough for anything in NA:
I did a review of this bullet when first released maybe 30 odd years ago. What was memorable for me, was the accuracy and I clearly recall getting groups a shade over half inch at 100 yards even from a Marlin .45/70, though I have to check my notes to see whether I loaded it in the heavier .458's.
When truth is ignored, it does not change an untruth from remaining a lie.
