When scoping a rifle that has the 3/8" or 11mm dovetail mortice, the best setup is to use a really nice one piece mount often used on high powered spring piston and gas ram air rifles. These mounts will have at least three (often four) allen head screws on one side of the mount and provide superior clamping force over a large area of the mortice. The air rifle one piece mounts are aligngned to provide for barrel droop. This is also good for getting all the elevation needed for rimfire rifles as well.
Stay away from the see through two piece mounts found at the sporting goods isle of discount stores.