I had about half a dozen that I was asked to 'rectify' as Rob was more of an engineer than a shooter.........they all flung a pellet without much recoil but that was about as close to a working/usable gun as they got.
Each of the rifles I worked on was individually hand made and slightly different as he obviously reviewed the design as he was going along, expect the triggers to be agricultural at best, the valving to be hit and miss - power can vary alarmingly.
Some require the barrel to be removed in order to charge with air so no real accuracy or consistency and all the ones I have seen had a power curve like Jordan's right knocker!!
Most used old webley barrels so that would be a good starting point for improvement.......
luckily Gedfinn wont see this as he was in love with Rob and his little frankenguns and would hurl an entire paragraph of late night drunken punctuation at any detractors.
"But we have our own dream and our own task. We are with Europe, but not of it. We are linked, but not comprised. We are interested and associated, but not absorbed."
Winston Churchill 1930