Let's start at the beginning. Is the scope base loose? Are the rings loose? Is the scope tube so flimsy that it is flexing if you push it?

If the scope is mounted correctly, it should not move. The Pro Hunter isn't that lightweight, and is probably at least 7 lbs with a scope. Unless you are shooting a magnum round, 3.5" should be enough eye relief. Please let us know how the back of the scope is loose.