Some interesting quotes about 5.56x45mm terminal effectiveness…
We had some issues with the 5.56 millimeter not being lethal or even slowing guys down.
We shot guys with a 5.56 millimeter center mass and had them walk in five hours later and say ‘you shot me.’ Then we would medically evacuate them. If you hit a guy center mass – he needs to die. That is the whole point of shooting at someone; not to do anything less than that. I would never go into battle without a 7.62 millimeter battle rifle now that we have that option with the SCAR-H.
Link to article (starts on page 9): http://www.sealswcc.com/navy-seal-ethos-magazine/issue/10/navy-seal-ethos-magazine-issue-10.aspx