I believe its a matter of genetic selection. As hunters, we have killed off all the "soft" deer over the years, and now the gene pool is made up of deer which are much tougher and require alot more killing than ever before. If you arent producing at least 3400 ft lbs at the muzzle you have a slim chance of killing a modern deer. I'm thinking of having a 50 bmg necked down to 338 so I can drive a 250 grain bullet at 6000 fps. I bet I would kill a boone and crocket with that! heh heh. The recoil and muzzle blast probably wouldnt be too bad either, do you think?