For kicks take a look at a 6.5 Grendel. At 200 yards the 308 and Grendel ballistics are very close. After that the Grendel rocks. Seriously last year I was looking at building a 308 in a AR platform. Where I stumbled on the AA 6.5 Grendel. I was impressed and excited. My goal is to shoot 500 yards by summers end. With the Grendel it would be a piece of cake. I just have to do my part
Good luck!