Just sold my DPMS ap4 and bought a rock river operator. Haven't shot it yet, but its sweet. A little heavy but I like it. I'm looking to put a eotech 517 with a magnifier on it. A got a troy rear flip up bui. I'm worried a magnifier won't be able to fit over the bui. Anyone run this? Also anyone have experience with sightmark magnifiers? I dont want to spend the 600 bucks on the eotech magnifier.