I agree, I think this formula is best applied to big bore guns and hard bullets that don't expand much.

I shot one particular deer with a .30/06, 150 gr pointed soft point, right through the ribs, hitting the offside shoulder. This deer lurched and piled up. Another deer I shot with a 45/70, basically the same range and almost exactly the same shot placement. That 400 grain bullet just whistled on through. The deer ran off, and went almost 100 yds. It was easy enough to find thanks to a good blood trail, but it just proves the point about bullet design.

To look at it another way, Taylor wouldn't have developed his formula if all they were after was deer. You have to get up to elk size critters before any of it applies. Also, everything I have heard is that African game is tougher to kill than similarly sized North American game.