Quote Originally Posted by TonyL View Post
Do you mean as compared to the recent 50/99, Paul? Those newer rifles are 26mm bore, the earlier ones 25mm. Can't remember if strokes and piston weights are in Bruce's thread in the Useful Section?
The standard synthetic sealed Oldschool HW50 piston weighs in at 200-202 grams, Tone.

Bore X stroke = 25mm X 65mm.

Transfer port = 3mm X 25mm.


My playing with HW50s, if it's any help ? :-

https://www.airgunbbs.com/showthread...16#post8129716


If I did another one I'd just increase the stroke by 5mm by machining the piston arbor to accept a TX piston seal then weight the piston back up to 200 grams.





All the best Mick