I use the 5.56mm M193 round in my guns to kill hogs, dozens of hogs; sometimes very big hogs. Very few of the hogs that I have shot with the M193 round require a second shot. The bullet will pass through a rib, or not pass through a rib; penetrate about 6", yaw and come totally apart. Shards from that little 55 grain bullet shreds the hogs lungs and heart, sometimes the diaphram and liver as well.
After about 150-175 yards when fired from a 20" barrel, the bullet loses velocity and much of its magic swine killing ability.