The Millet scope that came with my Serbu I bought lasted 2 rounds and it's blurry now. I assume the glass came lose. Can you guys who shoot .50's please tell me what scope you have and what rings you would go with. My rings are quite tight, but it is very obvious that the scope slid at least 1" in the rings. What model NightForce would you guys use if you planned to shoot 600-1000 yards?