i resently put a scope on my ruger 10/22.i have two sets of rings the see through ones which is taller up and a set of plain high scope rings.i like to have the objective as close to the barrel as posiable.on the high rings it was lacking just a little from the adjustable objective from clearing.so i cut a pop can and i put two pieces under the front ring and two under the back ring.this gave me the clearance i needed.will the shims be ok ? and stay where they are and not ever move after it has been tightened down.