The 6.5 Creedmoor has a 30 degree shoulder. So, you need a 30 degree neck turner if you are getting one with a specific angle. The SAAMI print online also shows a 30 degree shoulder. I had seen a print showing a 20 degree shoulder. If you see that one, it is incorrect. If your chamber isn't a tight neck chamber that requires neck turning, I don't think you'll see much gain from turning necks. There are two main ways to turn necks for a chamber. You need to know what your neck diameter is for your chamber and then turn the necks for the amount of clearance you want on the chamber. For instance, if your chamber neck was .290" and you wanted .002" clearance on a loaded round, you'd take your neck diameter minus the clearance you want minus your bullet diameter then divide that figure by 2 and that would give you the neck thickness that you want. In this example it would be .290"-.002"-.264= .024" then divide .024/2 = .012" thick necks. If you just want to uniform the necks and are not turning for a specific neck thickness, then you'd take a minimum cut on the outside of the neck, just enough to clean up the outside of the neck. You may find that turning necks is a lot of work for very little to no benefit. It all depends upon your chamber , your brass quality and how your cartridges already fit in the chamber. It doesn't hurt to give it a try. If it helps, great, if it doesn't than all you are out is the cost of the turning equipment and a little time on your part.
I had a couple of shooters that I was building rifles to compete in F-Class. One of them had a short range benchrest background. He initially had me build his rifles with tight necks that had to be neck turned to chamber in the rifles. He found that there was little benefit to turning necks for F-Class and went to chambers that were not tight necked chambers, but were instead minimum clearance chambers that didn't require neck turning. Both of those shooters wound up making the USA F-Class team a few years back shooting the minimum clearance chambers.
