Full power BSA meteor....

[Shed tuner]

Just overhauling mine today... machined an HW seal carrier with the male nipple that fits into the keyhole in the face of the factory piston (no buffer needed)... good thing there is you can swap between factory and HW heads in seconds. Adds about 2mm stroke which can't be bad, still easily clearing the cocking link.

26mm HW seal fits straight in perfect no sizing, slightly tight.

Added a 20g steel TH as the piston is clearly quite light. Bog standard well used std spring, gun is doing 10FP with 16 grains, 10.6 with 12 grain hobbies (.22)

I made no attempt to actually get it up to 11+ FP, but adding another 10-15g of piston weight, plus a little preload, would easily get you there...

HTH - JB