Great answer's Palm and Mad. For 3-400 yard's you wouldn't need the 20 MOA but if you do go to the Dakota's and happen to see a yote at 550 it would be nice to dispatch the deer eater. I use the XR on allmy AR's just because more is better in my book.
I think you'll be quite happy with it sitting on top of your RRA rifle.
http://i1216.photobucket.com/albums/...40/m-233-2.jpg