I saw a mk 1 or 2 airsporter for sale at Hale car bootsale in cornwall about ten years ago.
It had a recoil pad made out of the the cleated yellow sole of a workboot screwed to the stock, also for some strange reason the owner had dribbled fibreglass resin and camoflage skrim netting over the whole gun and painted it green.........and he wanted a vast sum of money for it. Is it still out there I wonder ?