There are companies that make .308 bolt faces that work well with the AR 15 carriers.
My 30 Sabercat is one of them that I make my rounds using 6 Dasher and 6 GT brass and both cases have a larger case volume than the 6.8 case.
However, if the OP plans to run light weight bullets than I agree that the 6.8 variants are a better choice, especially if barrel life is a concern.
