When adding a scope to a rifle that you've bought separately, you need to follow some basic steps to properly tighten it in place. Accuracy depends on how well it is tightened. In order to tighten your base screws properly on a riflescope, you will need the following: a rifle, a scope, and a Wheeler fat wrench. For rifle accuracy, your guard screws, ring screws, and the base screws will all need to be tightened. Your fat wrench is adjustable. So, start with it set at 20 lbs of pressure. Tighten each screw until it clicks. Set the wrench on 30 lbs. Tighten each screw. When all of the screws are tightened, then your scope has been mounted to your rifle to factory specifications.