Ahh gotcha. Lol I've been drinking a bit and didn't make the connection.

The reason for the 5.56 round is actually pretty fucked up. It's designed to "wound not kill" which sounds good on paper, the "intent" is that killing one person removes one person from the battlefield, while wounding one person removes 3. But the reality is that it's small and very high velocity to tumble and ricochet in the body after penetration. It's not unheard of to see an entrance in the arm and exit out of the chest for instance.