Just to be contrary, I'll pick one of the hot .224 bores.........anything from the 223 on up. I've shot a good many deer, both mule deer and whitetail with 223 and 22/250 and the animals don't go anywhere but down. Only trick to it is use 55 gr bullet and not one of the lighter possibilities.

Why are Americans so over-gunned? A 257 Roberts will kill any deer that ever lived and do it at any reasonable rangebut most shooters think they need something larger. Silliness.