Hi Dan, I have got in mind the possibility of weighting the barrel; not quite as sophisticated as the guy in the US who does the airgun blogs, but I like your idea to experiment with something readily available and repeatable.
I have been pleased with the results from the rifle when rested, it gives reasonably consistent groups; there is some muzzle lift, but I am certain it is happening after the pellet has left the barrel.
A copy of Robin's book sounds like the right tonic to sort out the wobbly blob hanging on to the stock...
Cheers,
Mark.
Too many guns, or not enough time?