This is my own personal BSA Airsporter S MK1 made on the very first day of production of this model.
It makes very healthy power and is very accurate. However, it is pretty brutal to shoot, as it’s stiff to cock, recoils heavily and has a very heavy trigger. It is running at mid 10 to high 11 ft/lb muzzle energy, which is too much for a .177 Airsporter to shoot sweetly at.
Therefor I am going to dismantle it, remove the current internals and save for future conversion. I will fit one of my own polished, optimized and deburred pistons, with a parachute piston seal conversion, powered by a standard TX200 spring (much lighter spring rate) with fitted guide and top hat. I hope to see around 8.5-10ft/lb output with significantly reduced cocking effort and trigger pull weight.

My Airsporter S MK1

Accuracy test RWS Superfield

Old piston, heavily greased with some scoring

Old spring with 3 collapsed coils creating effectively a piston weight and increasing felt recoil

New polished piston with parachute seal conversion

New power plant, ready to fit