Have an XM 15 E2 with Full auto (No 3 round burst thank God). Has the non-detachable carrying handle with a hole in in it that makes attaching a scope real easy. Also has a Stainless Steel barrel HBAR with a 1 in 9 twist. With a scope mounted it seems like it might be a somewhat acute angle that may make the point impact difficult to coincide with that of the iron sights. Just wondering because it is a real joy to shoot. Bushmaster with Sendra receiver.