Re: Long range coyote rifle?
If by factory you mean that you do not reload, I would suggest either the .223 or the .308. The .223 can pretty well to 500 yards, but the .308 with the heavier bullets would be better in the wind.
Personally I would go with the .308 for versatility and the readily available match grade ammo. It will easily be effective out to and beyond 500 yards on coyotes and even larger game with match ammo shooting Sierra Matchkings.