Hw35 Leather or synthetic piston seal ?

[Shed tuner]

Nobody mentions the differing size of the TP.
Strange.

Leather seal: TP 4mm
Synthetic seal: TP 3 mm

So converting from leather to synthetic needs sleeving down the TP to keep good shooting manners.

yup.. unless of course you do Mick's version of the synthetic conversion, resulting in a lighter piston and a longer stroke, in which case the larger TP may just be OK - but I'd bet it would still benefit from doing down to at least 3.5mm, if not the full 3.0

[T 20]

yup.. unless of course you do Mick's version of the synthetic conversion, resulting in a lighter piston and a longer stroke, in which case the larger TP may just be OK - but I'd bet it would still benefit from doing down to at least 3.5mm, if not the full 3.0

I ended up sleeving the transfer port down to 2.5mm on my O ringed 71mm stroked HW35, Jon.

[Shed tuner]

I ended up sleeving the transfer port down to 2.5mm on my O ringed 71mm stroked HW35, Jon.

yeah, o-ring with it's otherwise harsher landing would need some cushioning.. but I reckon std HW 30mm synth seal with a 69mm stroke and the 260g ish piston would be alot better on a 4.0mm port than it would with the 331g piston / 61mm stroke !