I am in the market for a new 16" mid-length upper and am looking at Knight's SR-15 and the Noveske N4 Light Low Profile uppers. I own and like Noveske, but I have no first-hand experience with KAC. I would appreciate comments based on experience. Weight is not an issue for me. I would like to know if the E3 multi-lug bolt design is proprietary to KAC barrels or if it is compatible with any other AR barrel extension. I can't find a lot of information on that.
Any input appreciated.

