RE: .243 ar-15 question
It would be more accurate than some, but less accurate than others. Not all bolt actions are created the same. There are some very accurate, and expensive, AR type rifles out there, but for pure accuracy, I'd stick with a bolt action.
You mentioned a 26'' barrel, but you'll find shorter barrels generally have an accuracy edge. The longer barrel gives you more velocity, but the shorter barrels are more common on the benchrest circuit due to the stiffer barrels.