I'm on my second Del-ton, a 20" 5.56 flattop upper, and all I can say is, this gun is a SHOOTER.  And a bargain, I paid less than $400.00 for this upper, and with a 6X scope, it put three shots at 200 yards into .27" on Monday.  Most of the time it'll shoot around an inch, but I'm sure with a better scope (or better eyes) it could do better.  Del-Ton's aren't pretty, not flashy, they just work.  I didn't even do a careful break-in on the barrel this time, I just shot it, and I keep it clean.  Hard to argue with results like that!
Papajohn