Remember, a sniper rifle STARTS at 600 yards and is often engaged up to 1,000. The .223 makes a poor choice for such distance. I am not saying that an M16 in the proper hands, can’t touch a person at 600 yards. I am saying that with a ballistic coefficient in the 0.23 to 0.26 range, and 55 grain bullet weight, there is not much ooomph left at 600 yards. In fact, the energy is down to a .22LR and the drop is approaching 120” at 600 yards.
http://gundata.org/blog/post/223-ballistics-chart/
Not that I would want to be hit by a .223 at 600 yards.
I understand that. I was just making a point.
Best,
L