Just an update. I finally got my 6mm Ackley done. I tried Varget, IMR 4350, IMR 4064 and RL22 with 75gr Hornady V-Max and Sierra 75gr HPs. All of them shot good but the Sierra 75 HPs shot REALLY well!
Here's the specs if your interested:
I had the barrel chambered and fitted by Dean Parker in Wellsville, Utah. He's a very successful benchrest shooter. I started with a Stiller Predator V action, left port, right bolt with no ejector. The barrel is a 1-8 twist, four groove, Palma/F-class weight Bartlein.
Dean chambered the barrel to 6mm Ackley Improved with a .271 neck which gives me a .001-.002 neck tension depending on how I turn my necks. It's a single shot so I can get away with low neck tension without worrying about bullets coming out in my magazine.
The trigger is a Timmney set at 1.75.
I topped it off with a Nightforce NXS 5-15x50 with MLR reticle. I highly recomend Nightforce scopes!
When the weather clears I'll get out and see how fast I can drive the Sierras before my groups open up.