. Sort of makes the 308 bolt action look sick, eh? you can have a sound suppressor on an 18" 223 (ie, 25" OAL) and still have a reasonably usable rifle. Not true of a "canned" 22" M1A.(ie, 32" OAL
Ummm, not really. You could have a suppressed 18" barrel .308 bolt action, and it would outperform a .223 in every one of those shots. And there are a slew of rounds in between the two that might be better than the .308, too, depending on application.
I shoot .223 avidly, and at 750yds it's lost enough energy that it is difficult to even seen the plate move without a good spotter. There's a reason it isn't used for extreme long range shooting, and the reason isn't because someone hasn't come out with another AR platform claiming to be the greatest thing since sliced bread. It's physics.