Explosive effect of an exit wound can and often does result in a reversal of expected reactions.
One would expect the head to snap forwards at impact.
But the pressure is really at the exit point.
So when the exit point blows out?
That can cause the head to snap backwards from the release of pressures not present at entry.
That's why Hollywood shots showing someone getting blown backwards are wrong with a through and through shot.
It's really simple physics. Think about it.
