Well as I see it, you are going to have to get higher rings or a smaller diameter objective. Higher rings will raise your head on the stock which may or may not be a problem depending on your stature and neck length. If you are set on using a 12 power, then you need higher rings.
Go to the Leupold or Weaver site and see the difference in ring height and I'd go up two ring heights - maybe "high". Buy either from your favorite retailer and save the receipt.
Good luck
