Hey Sgt-
My mistype sorry. I am thinking of .308 cartridge or 7.62 NATO round. My bad.
http://en.wikipedia.org/wiki/.308_Winchester
http://en.wikipedia.org/wiki/7.62%C3%9751mm_NATO
Had not even been thinking of the .30-06 cartridge.
I can see the advantage of the greater ammo load with the 5.56. I am guessing availability is about the same. But quality?