I took a new (to me) custom Springfield 1922 in .22 Hornet out to shoot yesterday. The rounds were landing approximately 7 inches high at 50 yards and there is no more downward adjustment left on the scope. Thus it appears that I'm going to have to shim the scope.

I'm assuming that I will need to add height to the front ring or under the front base (the bases are mounted on the receiver ring). Approximately how thick a shim would I need to insert and would I be better off placing it in the ring (and if so, how do I deal with the reduced interior ring diameter) or under the base?

Thanks.