If you look at our rifles it seems like in theory the 5.56 is devistating when it fragments but since we are not allowed to use hollow points many hits do not result in a full energy dump.
I'm guessing that you are talking about the military here. If that is a correct assumption then I will let you know, our military is allowed to use hollow point ammunition; just not ammunition expressly designed to mushroom and cause a larger wound cavity. Snipers are using OTM (open tip match) ammunition, and many special forces units are issued 77 gr OTM ammo as well. I recently found out that some conventional forces occasionally get 77 gr OTM ammo (though that might not be as common).