After being a participant in the First South-East Asian Wargames(Second-place) and another 20 in the Air Guard as a Small-Arms Spec(7-level) any AR platform in 5.56 is the last thing I would grab if range were any issue at all. AAMOF, any AR platform in 5.56 would not be even my third or fourth choice. Any thing over 100 yards where anything but concealment was involved, I would go to one of my Main Battle-rifles.
It's not a problem of being able to hit with the platform it's the fact that you have to do it multiple times to achieve any telling effect at any range past 100 yards. I've learned the hard way not to trust my life to a .22.
If I have time to get to a rifle, they'll deal with one of my Garands or my M1A or my FAL.
"Diligentia, Vis, Celeritas"