I have a 14.5" Noveske Switchblock upper. They're the tits! If you can get one, there is no better SBR setup IMO. The nice thing about getting the barrel from Noveske is the Switchblock is pinned, rather than the bolt on they offer for other barrels. My favorite other SBR barrel is the Colt 6933 11.5". They're very light weight.