I really do not know about the physics, but I have seen several wounds from AK-47’s. They tear out large chunks with them because most of the energy goes into and stays with the body being hit.
I have not seen M-4 wounds, but M-16 wounds that did not hit something solid usually went out the other side pretty quickly.
Maybe hitting a bone or piece of metal changes all that, but the AK-47 wounds were “religious expletive” awful.
***but M-16 wounds that did not hit something solid usually went out the other side pretty quickly.***
Would that be the original 1 in 14 twist, the later 1 in 12 twist, the 1-7 twist or the 1-9 twist.
I’ve read the original 1 in 14 twist was devastating but the bullet would tumble before it hit the target in cold weather.