I bought a Sabre Defense 14.5" 6.5 Grendel barrel from another forum. It new unfired, and "in the white", meaning it has no finish, just bare steel, looks like stainless. I had originally planned to have it chopped to 12.5" and rethreaded in 5/8" ( Rainier Arms for $60ish, currently muzzle threads are 9/16-24 ), but didn't do anything with it.
Asking $150, possibly open to partial trade for 6.5 Grendel AR magazines
it looks like every other 14.5" "stainless" M4 barrel, no markings on it that I recall, needs a finish applied.
Cold blueing/cerrakote/duracoat/brownells aluma-hydeII/krylon etc.