The Christensen Arms 6.5 Creedmoor Stainless Steel Aerograde Carbon Fiber Wrapped Barrels will fit most AR mil-spec uppers with normal tooling and tolerances.
it has a gas block and gas tube attached to it...that means it is for the ar platform. this one specifically is for the ar-10 platform which fits .308, 6.6cm, and a few other larger calibers. hope this helps you out in the future