Randy - Jeff is correct. I don't want to loose my rear BUIS. In my opinion, ALL primary rifles should have BUIS. The GSR's rear sight is mounted in Ruger's integral rear scope ring notch. I also like a forward mounted scope because they can be used in a "both eyes open" fashion. This means you have 100% greater situational awareness, and can "snap shoot" with the magnified optic.
Jeff - I'll probably end up with a set of quick-detach rings. I think the eye relief can be achieved this way.