Useable for what? Reforming to to 6.5 Creedmore?
I don't know, but your results will probably be better if you buy the correct brass to begin with. LMT's .308 is new to the market and I think just great in .308. I would put 6000+ rounds down the tube in .308 before considering a caliber change.
6.5 Creedmore will really shine in a dedicated long range bolt action rifle, as far as semi-auto feeding and function, I think you're breaking new ground if you decide to go that way. Very few semi-auto rifles have ever been chambered for it.