If there is any play at all in that bad boy, you ain't gonna hit the same spot consistently. Do what you have to do to get it tight. It absolutely should not move. Also, 3.5 eye relief should be enough. I haven't had any experience with that scope. I shoot out of Leupold VX-I's exclusively. Relatively inexpensive, plenty of eye relief and with Leupold's full lifetime warranty, you will never have to buy another one. Sure, there may be more expensive scopes that offer a little bit better performance, but this is more than sufficient for me.