Guys I talk to who are downrange say 5.56 brings the pain just fine. The 77gr OTM ammo is apparently well liked and received.
Are your friends in Iraq or Afghanistan? I’ve been reading a bit about how 5.56 doesn’t have the range needed in Afghanistan, and the Army has been re-issuing some M-14s, and that it was also the impetus for SOCOM wanting the 7.62 SCAR-H rifle.
I'll say this as someone who didn't shoot much prior to joining the Army. Lots of Soldiers aren't really that well rounded as shooters. I was very pleased with my M9 Beretta and M4 until I worked in a SOF unit and got to play with some other toys. My first deployment to Iraq, I had a 1911 that must have been pulled out of mothballs from the Korean War, and it shot like a champion. The M9 felt like a cheap toy after that.
I also spent a few years downrange teaching, after my enlistment was up, fielding new gear around theater(s). Soldiers instinctively get by with whatever tools they have, and have faith in their gear, even when there's a lot better stuff available. Partly because that faith gets them through some tough spots, partly because they just don't know any better.
While I'm always interested in what the troops have to say about their requirements and experiences, a little perspective about their perspective goes a long way.