Defense rounds are designed to transfer all energy into the target. In a perfect scenario, one would expect the projectile to simply fall out of an exit would. Target or FMJ rounds could be expected to travel through target with enough energy to penetrate whatever is behind initial target.
It is my understanding that 223/556 main difference is how much powder is behind the projectile. I would not expect to see massive trauma from this round unless it traveled through minimal flesh such as extremity or neck.
Surely some salty vets can lend their opinions on this?