I have shimmed the base ,the rings and have used shim from a tool and die shop and pop can .....the best I have used is from Brownells and has the holes pr edrilled for the mounting screws and is used under the Base not the rings as to not stress the scope ....JBPercision has given another source
for this. I have used pop can to get out to 1000 yards with
B&L elite 4200 6-24 with .308 and 155gr bullets.
