I have used aluminum from a beer can, cut a small square to fit, on my 10-22 with leupold bases because I could not get the scope adjustment I needed from the 40mm scope. I have been troubled by the fact that this alters the geometry of the scope base (ie: scope tube is not parallel to barrel) in relation to the barrel. I shimed up the back of the base, so now the scope tube is tilted forward a slight bit. Can anyone clear this up or is it a real problem?