RE: 22-250 for deer hunting
The 5.56mm round was chosen because it was lighter, cheaper and had more range than the current .30 cal ammunition.
As much as you want to think killing the enemy is the point, it is not. Achieving the military goal is. Out of commission is out of commission whether dead or not. Wiping out the enemy is not usually the goal, getting them to fall back or surrender is.
If in war we were worried about clean kills no one would be using ball and FMJ ammo in rifles that have better cycle rates than they do accuracy (AK). We would be using more accurate platforms with better sights and ammo that was designed to make cleaner kills.
You can never really compare military weapons and ammo to hunting and self defense situations. They are to completely different beasts.
Look at what a sniper uses when he goes to intentionally kill something. He basically uses hunting equipment, not combat weaponry.
My take on it anyway.
If you can kill a deer with a cap and ball musket, a .410 shotgun, a handgun or a bow I am pretty sure a high powered rifle will get the job done if you put the bullet in the right place. I think we tend to over think things too much sometimes.
Paul