I just picked up a PRI Delta forend for my SPR (5.56) build, and also picked up the full length top rail for it. The top rail has a bit of an overhang over top of the rear section of the upper receiver where the PRI flip up sights were designed to be mounted. Does anyone know if there are any other sights that are lo-pro enough to fit the same space? I'm hoping the Magpul MBUS Pro's will fit, but am open to other options as well. Any help would be appreciated.