A shim on the bottom of scope between the scope and the lower half of the rear ring will permit the crosshairs to be adjusted to point of bullet impact. I use a shim made out of the flexible plastic used for clear flexible display sales container. The plastic package the razors are sold in is what I prefer. Cut the plastic no wider than the rings and no longer than 1/2 the diameter of the scope. No shim on the top half of the scope. Flat or slightly curved plastic works best. Trial and error will tell you how much thickness is needed. Usually one thickness is enough. Remember that to raise the point of impact, you raise the rear of the scope. That will permit you to align the crosshairs with where the bullets hit.