Hi Paul.
The HW35 is one of my favourite platforms to play with, I found my 1972 HW35 was very easy to get upto 15ftlbs with a piston head change and a longer stroke --- I should point out that this happened accidentally after I sealed the porous breech.
The earlier leather sealed HW35s normally had a 65mm stroke and a 4mm transfer port, Hw35s after serial number 843636 had a lighter synthetic sealed piston and a stroke of 69mm and a 2.8-3mm transfer port.
Starting with the earlier leather sealed piston it's very easy to alter them to take a synthetic seal and alter them to a 71mm stroke for a calmer firing cycle.
Venom used to advertise the early HW35 at 15ftlbs at FAC power, from the few pictures I've seen of the internals of these guns they used an O ringed piston head with a longer stroke.
Once the synthetic seal was introduced in 1981 Venom seam to have ditched using O rings as the factory seal was efficient enough to get the job done.
I'm presently rust bluing a .177" HW35k barrel to fit to my .22" HW35 with rotary piston in order to bring its power back under 12ftlbs --- I'd rather swap barrels than mess with action, and .177" pellets are cheaper than .22".
All the best Mick
Originally Posted by T 20
Hi Paul.Cheers, Mick.
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