If you are shooting High, as in your POI is above your POA then by shimming under the rear, you are making it worse. Take the shims out. If you are still shooting high, and have no adusment left in the elevation, then shim up the front.
I would try it again with NO shims and make sure you are dialing your elevation the correct direction. You need to move your POI down, so you turn the knob down/clockwise
