Okay, I'm in the midst of building an AR-15 with my dad. The lower is all wrapped up and ready to go, now we're shopping uppers. The upper that he's most interested in is a CMMG, and it has the F marked front sight gas block. My problem is, I know he'll be getting a scope, probably a 4-12x40 or x44, and it will be in a Burris P.E.P.R mount. I'm concerned that the front sight will partially obscure the view in the scope. Anyone have this type of setup that can help us out?