here mine and the wife's. Mine is the longer 20 inch barrel with a 1 in 7 twist which I don't care for much going to rebarrel mine at some point to a w in 9 twist so I can shoot the lighter bullets has a burris black diamond on top. Shoots ok. Wifes is a 16 inch barrel with a nikon m223 scope and is a tack driver. The nikon is one heck of a scope highly suggest it. Both with p mags free float hand guards and timniny triggers. I built both.
Man it is amazing what that nikon scope can do. I kept doing research on them til i finally said hek with it and bought one for my black ar. And good greef that scope is serious business. Super accurate