Hi,
I know this is a pretty obvious thing to say and I wouldn't be saying it if it hadn't happened to me! When I received my 50mm nite-eye scope I tried to fit it to my MFR. I hadn't realised that I would require some mounts to raise the scope higher to stop it fouling on the barrel! (Doh!)
I only realised my mistake when I was shooting about a foot low!
Luckily I hadn't over-tightened the scope and didn't bend the tube. I have since aquired the correct mounts and am now happy with the setp.
Mac.