JonOriginally Posted by Jon Budd
Agree completely, so obviously we have to compromise somewhat... the 2" of preload with 3mm gauge springs in my TXs is a good compromise IMHO.
Pity you are a gazillion miles away, we could compare shot cycles
My HW55 is long stroked, uses a somewhat smallsih spring (wire dia) and due to restricted spring length room is limited to 10.5FPE although I may be able to get 2 more coils in if i machine the trigger block face back a tad (like i did on Pauls 50s) The piston is light..200g ish (forgot exactly but will measure it up again), the firing cycle is fast....the accuracy is very high (superdomes at 750fps or so). I had to sleeve the transfer port down to 2.7mm from 4mm to get it to behave, at 4mm it was brutal on the trigger finger after 20 shots or so. Now I believe i get away with the 55 as it is due to the piston weight, i have a similar setup in my .22 280k, i short stroked to 64mm and this too had a 4mm transfer port 22mm long and at this stroke it easy made 11+ BUT due to the lower swept volume and the heavier weight of the piston it was not slammy...but very very gas rammy. I decided to follow the model of the 55 and sleeve the port down and went to 2.6mm with a venturi at the piston end and 10mm at the breech end opened to 2.8mm...utter transformation although the power went down a tad due to the more restrictive port...so I added 4mm of stroke back on and left the 4mm of preload i lost off the spring...end result was 99.9% the same as that at 64mm but more power.
The question however is what is better, light weight fast pistons with longer stroke, or heavier pistons with shorter stroke giving the same power. Dave's 77 is supremely fast, i watched him shoot it and he was in awe of the accuracy...truly all pellets thru the same hole at 30yards, BUT I was seeing the same from a 440TH with a very different shot cycle off a bag and off hand...totally different setup with a much heavier piston.
I like the 55, i like the accuracy of the 440TH...which is better? I have no clue
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