I have Rock River gun , DPMS , Bushmaster. And know super cheap Bear creek. It’s a sickness owning all these AR15 guns.
At one time i would have said spend the extra for the Rock River gun. now a days machining , barrel makers , etc all have excellent machines and people that run them. If you have the money go with rock river gun they guarantee a inch group at 100 yards out of box. With that being said , all guns I mentioned shoot 1 inch groups at 100 yards after I find them the right factory ammo they like. If you buy the other guns mentioned you will have enough money to buy 1000 rounds of ammo. Marty