built a new gun with egw 20moa base with leupold prw bases took it to the range and it was way off @ 100yrds (high and right ) tried swapping one ring 180 degrees and that took care of the left/right for the most part but it is shooting 8" highand i have ran out of adj.. was told i need to shim the scope 10-15 thou. i have never shimmed a scope before i've been reading about shimming the base no the rings but what is better scrap the rings for burris sig or shim if ring how do i shim a pic mount?