I have an air rifle that has some bad barrel droop and need an elevation adjustable scope mount or rings that fit a weaver base and are 30mm if rings. Its currently wearing a cheap scope that came with it that I have shimmed in the rear (four layers of beer can) to make it actuall shoot to POA. Just don't want to shim that much when I put a better and more expensive scope on it. Any suggestions before I have to basically bend the barrel back to true (which is what a very well respected air gun smith/tuner suggested)?