I've been wanting to build an AR with iron sites only. Im thinking of picking up a colt 6920-oem2 and putting a noveske NSR rail on the front with a set of fixed sights like the daniel defense ones. I picked up a year or two ago a colt CS stock and i'd like to put that to use. I think that would be a nice simple setup but i wonder how reliable it would be with the rifle stock and carbine length gas port. im also considering cuttin the barrel down to 14.5" if that makes a difference.