3-shot or 5-shot?
Most ARs, in my experience, are not sub-MOA guns. If you can get 1.5" 5-shot groups out of it with decent factory ammo, that's about as good as you can reasonably expect. Some factory guns will shoot better than that, and many will shoot worse. But in my experience, that's about the best average group you can expect from 6920-level AR (anything in that same price range with roughly the same features and build quality).
Though I've never shot one of the more expensive models myself, I've heard those can get to MOA or slightly better.