M4 (flat top receiver) with an Aimpoint. all you have to do is get the right height mount ( I used the shortest mount for the comp m4, and it will allow "co-witness" or use of both iron sights and optics at the same time.
also an m14 (clone) can do it. all you need is the right rings for the scope. and a mount that has a channel to allow you to use the irons.
I think of these 2 off hand, as i have them set up this way.
Last edited by triggernick; 02-14-2011 at 11:01 PM.