I had been looking for a Colt manufactured AR15 type rifle and have found a pre-ban Lightweight Sporter for a good price, now I am trying to determine if it is all Colt parts before I purchase it. The lower is obviously Colt as it is so marked, but I can find no Colt markings anywhere on the upper. On the top of the barrel it faintly reads "C MP 5.56 NATO 1/7". Anyone know if this is a proper marking for a Colt barrel? Or, if there is normally anywhere else on the rifle that Colt markings would exist? Any help would be appreciated!