We'd have to compare, side by side, the .308 Win case, the 6.5 Creed case, and this 8.6 BLK case. If we run .308 Win brass for this, we'll be pushing the shoulder back a bit, and expanding at the same time. 6.5 C has a good bit of case taper to it, over a straight-cased (almost) .260 or .308.