Re: .260 accuracy
I'll vouch for RiverRat's 260s. They're accurate as can be. One of his shootin' buddies routinely tops all comers in 500 yard F-class matches, clangs steel at 600 with boring regularity, & is a force to be reckoned with at 1,000 in light wind.
Yes, the .260 is a VERY accurate caliber.
What bullets & powders have you tried so far?