I just picked up a Ruger American Predator in 6.5 Creedmoor and been trying different loads in it. So far it likes 123gr. Hornady SST with Hornady brass, CCI 200 L.R. primers and Reloader 15 powder. 1/4 inch groups at 100 yards.
Also, I have a R.A.R. in 30/06 that has about the same accuracy but I had to sand the one side of the barrel channel because it was putting pressure on the barrel and throwing the shots off. It's all real good now. And the 06 has a 3x9x40 Nikon on it.
Good luck and that should be a good scope for your rifle too, I don't think caliber matters in the way these rifles shoot. Just about everybody I've talked to that has one of these rifles say the same thing, they are very accurate for a factory rifle.