Agree on the mount

as Mark said, get a good solid mount before frustrating yourself with the stock cheapie. You will want the scope far enough back to get a clear picture of the full diameter, with no dark ring. You can determine this by bringing the rifle to shoulder naturally, you shouldn't see a dark ring. You can adjust the ocular focus by bringing the rifle to shoulder and pointing at a plain white wall, the crosshairs should be sharply defined. Use a wall with no relevant features that will draw your attention, and don't linger as your eye will focus to correct. You should see clear crosshairs and the full ocular diameter when you shoulder the gun, without having to creep forward on the stock. Hope this is clear enough to understand.