I have posted in the other threads as well; I'm always playing with stuff, and my current set up on my 455 Canadian .17 consists of a Scorpion G2 17 4X12 with a set of fairly high amazon rings. The larger eye piece actually dictated the higher rings as with no rear sight, the 40 mm objective lens cleared the barrel with medium height, but eyepiece interfered with the bolt handle. I went with this scope as the ballistic turret is pre-calibrated for 17gr Hornady loads, which is what I have been shooting exclusively. SFRC had a 16% off sale a few weeks back, these scopes are amazingly clear, and are great value for their money.
My 455 .22 trainer uses a rail adapter with low rings; the extra clearance was needed for the Tasco target scope and the rear tangent sight.