I am thinking about ordering the 16" M4 Rifle Kit from Del-Ton and would like to put optics on it. I assume that the A2 sight would interfere with optics. Would I be better off getting a 2 rail, 4 rail, or 2 rail with detachable front flip up sight??? I would think I could find a flip up sight a little cheaper somewhere else but still need to decide on 2 or 4 rail. Any advise offered would be greatly appreciated.