The hunter used a 77gr OTM bullet. A 77gr OTM 5.56mm bullet is frighteningly lethal.
That 250lb black bear would have dropped just as fast with one round, but because the AR-15 has almost no recoil, he probably double tapped the bear.
That bullet is an FMJ hollowpoint that will produce excessive fragmentation while still penetrating extremely well. The bullet will also frag at velocities as low as 2100fps whereas a 55gr M193 or a 62gr M855 Milspec round needs usually at least 2700fps to frag.
A 5.56mm with that bullet is probably as lethal if not more so within 125m than a typical, traditional .308 or .30-06 soft tip. Most hunting kills in the US take place at 180m (200yd) or less. Most combat kills with small arms at at ranges less than 100m. Most USMC sniper kills in the invasion of Iraq were at 300m or less.
At that range (40 yards) a Milspec 55gr FMJ M193 round would have also done the job. At those closer ranges, the 5.56mm is actually more lethal than many of the more traditional .30 caliber hunting style bullets.
I've seen a man, about 190lbs, who was hit with one round in the upper left torso near the shoulder, about 3 inches below the collar bone, with an M-16A1 using 55gr M193 spec FMJ ammo at about 15m and the exiting bullet took a piece of meat out of the back of his shoulder the size of a large orange, the shoulder blade was pulverized, the collar bone was badly broken, the fragments and hydrostatic shockwave ruptured and collapsed a lung, and the fragments and hydrostatic shockwave damaged his spinal cord, leaving him permanently partially paralyzed. The fact that he lived at all was quite surprising, but that was probably due to rapid medical attention.
Another graphic example was when I shot a large attacking rottweiler at a relatively close range with one round of 55gr M193 ammo from a Ruger Mini-14. The round hit the upper torso and it opened up his entire body cavity like a freshly gutted catfish.
A 5.56mm 55gr M193 spec round will also drill though a thick steel bumper, spraying fragments out the other side. The 5.56mm round will go through one layer of a lot stuff, and then, once through that layer, the bullet usually break up. For instance, if you are on the other side of an automobile (multiple layers), you have some cover from a 5.56mm round, but anyone inside the car is hamburger.
). I know; let's send him to Africa to hunt Cape Buf's with his AR-15! Darwin would be so pleased.
