M855 green tip 5.56 Nato will go straight through a vest & trauma plate.
I would not want to be on the receiving end of the m855 or the m193 I was hit without armor by 7.62 x 39 it was like being hit by a truck!Depends on what level armor.
Lvl III+ and IV will stop M855 cold.
Funny thing—M193 will sometimes penetrate armor that will stop M855; slightly higher velocity does the trick.
Trauma pads can only do so much.Nothing like blunt force trauma...