which way does it need to go, my guess is if you set elev to neutral you need to tip the front of the scope forward because its shooting low, correct .. shimming doesnt lend itself to holding a good zero so what i'd do to save money and avoid a fancy mount is get a dowl thats slightly 'smaller' than your tube and carefully work the bottom of the front ring down keeping it square .. i'd use about 120 grit to cut it down then 220 to polish it up .. careful where you touch the ring and dont hit the sides and scuff it up .. you may have to chop some of the flats down alittle if you lose too much of your gap to tighten correctly and if it needed to go that far i'd 'relieve' the appropriate edges so the risk of biting into the scope is reduced, just picture the scope tilted in the rings and which edges would tend to bite in and roll them over slightly .... but i'd work it down slow and test until you got it .. .when your all done if you were careful alittle flat black paint on the worked area and tape off the rest ... reapply the protective strip, yeah dont mess that up try to get it off in one piece ..