I'm working up a load in a new barrel, the reticle is maxed out on elevation, and my POI is still about a foot low. Can I put a shim under the back ring? If so, how thick? Or do I need to get a base with angled elevation? I'm hoping a shim will work but I don't want to waste time and ammo if it wont. I don't need to be exactly on target because I'll use another scope once the load is worked up. If I can get it within 3-4 inches I'll be happy. Thanks in advance guys.