well like all caliber wars there are so many things to figure in, especially the what ifs?
generally speaking a rifle round is going to do more damage simply because it carries with it a lot more energy.
but then what type of projectile does it carry on the end?
is the projectile so near unstable that it tumbles or does it pretty much drill a nice lil round hole right through the target?
the 223/556 lets face it is not considered the killer cartridge that so many think it is, in the AR it is a very effective wounding machine though.
I mean the cartridge has under gone a steady change/improvement to better make it a killer round, but its not a 308, 30-06 0r 50 cal for sure.
but you sure can a carry a lot of them lil bitty Booletts!