Thanks Gents.
Craig,
Didn't know that, sounds like a few quid though!
Baz,
Thanks, but that'll surely keep the same scope height?
Chris,
Yes, my lad is going to try HFT with a 10x44 Viper and an S400 and in my wisdom, I thought I'd help with the closer targets by dropping the scope. Maybe let him just him shoot and don't be an interfering dad!