I've heard of using photo negative strips to shim up the front or rear rings to allow any sighting in issues to be resolved, this I believe is used a lot with air rifles, where they cannot get, or have too much elevation, you shim up the bottom part of the ring dependant on what you need in elevation. When I bought my Air Arms 510 extra, I had the same problem and was told to do this mod, told the shop to replace the rings and put the negative idea where the sun don't shine, replaced rings were OK. But what can you expect from the product we all know is used for air guns to mount scopes. deerwarden