If I were to buy a .223, I would choose a competition model AR over a bolt gun any day. They are as accurate if not more accurate than a bolt gun and are alot more fun to shoot[8D]
I have always believed that bolts were the most accurate around. Why is it that snipers use these exclusively? Less room in the chamber for potential misalignment.
Semiauto rifles have been used as sniper for a very long time- SVT-40' s, Gewehr 43' s, M1C' s, M1D' s, M14' s, Dragunov' s (built on AK actions), Stoners, (built on AR actions) Barret .50' s, even the .50 Ma Deuce machine gun, not to mention that european forces probably use something based on a FAL or G2 for sniping.
A carefully fitted semiauto will lock up just as tight and true as a bolt action, in fact alot of modern semiautos use a rotating bolt that locks up just like a bolt action.