Wheeler 113088 Level-Level-Level Scope Leveling Tool
The Level-Level-Level works because the scope is leveled to your receiver, not to the top of a scope base. Level your scope as you mount it on your rifle. The magnetic base in the rifle level bridges the bolt raceway, allowing you to position your rifle perfectly level. Then level the scope, tighten the rings & your done. Works with practically any bolt-action rifle, and is adaptable to other designs.