Air Arms TX200 / Prosport Piston Extension
TbT Piston Extensions shorten the stroke (movement) of the piston to reduce recoil and hold sensitivity. The reduction in swept volume will initially result in lower power. This can be countered by tuning transfer port dimensions*, increasing preload on the spring or replacing the spring with a stronger one. The idea is to expel the smaller volume of air faster to achieve a similar power, thus reducing lock time.
Take the piston and carefully remove the piston seal. Place the extension on the seals locator. Ensure the extension is placed centrally on the piston. Looking from above there should be an equal amount of the piston visible all around the extension. Tighten the grub screws in turn a little at a time until the extension is secured. Do not overtighten! Ensure the extension is still central to the piston. The use of Loctite is recommended!
Reassemble the gun and check the power.
Tinbum Tuning accept no responsibility for your rifles legality. After any work check your power levels with a chrono!
*More advanced tuning should only be carried out if you know what you’re doing!