I never like using a round that is adequate for the job. I want a round that is overwhelmingly overqualified for the job, PARTICULARLY when what I am shooting at has the potential to kill me.
There are a couple of distinctions to remember here. One is how the rifle is actually employed in battle. Assault rifles are used to support the squad weapon or medium machine gun. While the squad weapon in this case actually shoots the same round, it shoots fifteen of them per second. The individual soldier's rifle is used while the squad weapon is providing suppressing fire, allowing soldiers to move. It is supplemental to the heavy force provided by the big guns. When soldiers use this rifle to clear houses, etc, it is always under cover and support of heavier guns. Now under most cases, soldiers who are clearing buildings also have shotguns.
Another distinction is that soldiers use burst or automatic fire. While I wouldn't pick one hit of 5.56 as the ideal man-stopper, I think three of them will do the job just as often as a heavier round. This is an option that soldiers have that the rest of us don't. I tell my soldiers that when we are training for marksmanship, their first priority is making sure that as many of their shots hit as possible. Their next priority is doing whatever they have to to survive. (Speed is fine, but accuracy is final.) Anything worth shooting is worth shooting twice. PARTICULARLY with the weapons they are issued. I would rather use the rifle and round that lets my petite female soldiers get as many hits as possible than the heavier rifle that they can't use effectively. I THINK, that we will move into a new policy of weapons procurement for the military in which heavy combat units and special forces units will see more flexible policies and funding for mission-specific weapons, but the rank and file support soldiers will use the M-16/M-4 for a LONG time to come.
For people who want to use an AR for their HD weapon, I say, go ahead, BUT, don't use the same ammo as the military. Use a dedicated load like Hornady TAP.
For hunting, I don't plan on using .223 for anything bigger than coyotes. I know guys who use .223/22-250 for deer, and are very effective with them because they know the rifle's limitations well enough to make ethical shots. I have also been in heated discussions with hunters who used these cartridges for convenience, wounded the animal, and didn't care. They refused to recognize that their choice of caliber may have been too small. Shot placement is certainly important, but you can say that a .22 is adequate if you can put that 40-grainer in the deer's eye every time. Shot placement is important no matter which bullet you use. But a heavier bullet gives you more room for error.
Again, 'adequate' isn't a word I like to hear when my life hangs on the shot. And remember, if you are fighting for your life, if the bad guy is capable of running away and dying, he is also capable of continuing to attack you. I don't want him capable of doing ANYTHING.
