I'm really starting to think that these 21/22mm bores with their longer strokes...

[Shed tuner]

surely reducing stroke would increase slam and reduce power [enable more spring] so could you not simply shorten stroke a mm at a time untill you hit the sweet-spot

Can't shorten the stroke, need it to make the power...

I'm happy to be proven wrong, but I don't think there's an easy answer here (except maybe the weaker, longer spring with more preload - but even that's hard to find)

** edit just run the numbers with weaker spring, more preload - only reduces the piston bounce at exit my 0.5mm, but it's a start...

[tinbum]

Maybe we should tune them for more "slam" ?

In the name of all that is holy no!!

As impressive as the small pistoned guns are, they are not exactly pleasant to shoot. One comment I heard at the last bash was "I know we don't want piston bounce, but it would be nice if it slowed down before slamming into the end!"

I doubt it was one of yours, but they all have a hint of "car-crash" in the action already.

[slugger]

what i meant was, shortening the stroke would enable the use of a meatyer spring........which would make more power, then drop the stroke untill its at a nice fast 11 - 11.5 ?
less stroke should equate to less bounce-travel too. win win ?

[Shed tuner]

In the name of all that is holy no!!

As impressive as the small pistoned guns are, they are not exactly pleasant to shoot. One comment I heard at the last bash was "I know we don't want piston bounce, but it would be nice if it slowed down before slamming into the end!"

I doubt it was one of yours, but they all have a hint of "car-crash" in the action already.

Well, my experience is that the 22s are much softer than the short stroke 25s, so I'm not sure what gun was being commented upon. But I agree that slammy actions don't feel nice - however, they *may* be less hold sensitive than neutral ones (and bouncy ones are defo poor in terms of hold sensitivity).

[Shed tuner]

what i meant was, shortening the stroke would enable the use of a meatyer spring........which would make more power

Nope, it won't - the stroke they are at is the minimum to make the power, with any spring, such that adding preload / meatier spring reduces power, not increases it. They are right on the limit (in terms of spring power for the given stroke)..

[TonyL]

Yes it was on one of my threads I think - the HW80 (24mm) one...

Now that thing is shooting nice - I can watch the pellets with ease I also cold blued it, so it's a little easier on the eye

So, that's it, then!

24mm; settled??

24 just sounds such a nice number......

Please, please, pretty please can I have a go on her at The Bash?

[Shed tuner]

So, that's it, then!

24mm; settled??

24 just sounds such a nice number......

Please, please, pretty please can I have a go on her at The Bash?

I do think 24 and 23 are where it's best - of course you can play

Just need to find a decent scope for it, the one I'm using right now has a rattle and shifts zero every half-dozen shots

[TonyL]

I do think 24 and 23 are where it's best - of course you can play

Just need to find a decent scope for it, the one I'm using right now has a rattle and shifts zero every half-dozen shots

Thanks, JB.

[Shed tuner]

i love all the new ideas and experiments. and untill i get to try them for myself i cant conclude anything obviously..

Seb, you REALLY need to get yourself to Mick's bash......!!!!!!!!!!!!

[slugger]

i know m8 ....... i just know i would love it too, but there are 'issues' that need resolving first....... things like ....... seeing my lad weekends/holidays [lives with his mum]....... work [im going to be taking over the running of the bike shop 3-5 days per week] ..... in short i am [or it seems] always at the mercy of others....... makes it immensly difficuly to plan anything for myself
never say never tho its well and truly on my to-do list, and right up there priority wise

[look no hands]

i love all the new ideas and experiments. and untill i get to try them for myself i cant conclude anything obviously..
but i will say that my home-brew tx [25mm still] is the easyest of all springers ive ever tried to be accurate with.
i cant enphasise enough just how rubish MY shooting technique is, i mean seriously, i cant shoot for shizzle unless rested, and even then i catch myself doing a bad-hold, not balancing the rifle, changing hand position, pulling into my shoulder, forgetting follow-through, you name it, i forget it
but......
this tx is so forgiving that the only time i miss any of my targets is if its windy/gusty ..... and me not guestimating windage correctly
point being, maybe being too efficient is ultimately going to show-up minute differences more...... for example pellet fit....... if you are operating to the very n-th degree of efficiency, then a sudden tight pellet will massivly effect pellet-release-time a lot lot more than an "alround tune" so to speak ?
or a change in temperature even ?
i dunno, im liking the idea of experimenting further with the tx, but im so loathed to mess-up what works so well

I feel the same way about my Prosport and my HW/XS20 hybrid, neither of them have been fettled to a high standard and basically both have got drop in kits (actually the XS20 has a matching " found in the parts box" spring that fitted the guide well) but they shoot really well, the PS is so quick, I'm sure if someone else shot them, they would think differently but to me they seem to shoot just right and I shoot them well as they are, I'm very tempted to get the XS20 properly tuned but I'm a little reluctant at the moment because the way it is.

Pete

[Shed tuner]

This is the cool thing about the bash and other events - you get to see what you are missing - or not

[Gecko]

"It's hard enough to find a soft enough spring to not over-spring these 22s"

could that be a contribution to the bounce issue?

[Shed tuner]

"It's hard enough to find a soft enough spring to not over-spring these 22s"

could that be a contribution to the bounce issue?

Almost certainly, yes.... a downside of them being so efficient !

[Black Beard]

Not really, as the small bore has less air to compress, and that air presses back over s smaller surface area, reducing the decelerative force, so the piston is decelerated less, so it's overall journey time is actually shorter... however, see below...


Been running some numbers on the top secret funky recoil simulator:

Bore & Stroke / exit time / piston bounce dist / action dist / max piston bounce
25mm & 78mm / 10 / 5.9 / 4 / 28.4
22mm & 92mm / 9.7 / 7.7 / 3.8 / 36.9

lock time (pellet exit time) is actually a fraction quicker on the 22, but the difference is tiny.
the action dist recoil is 0.2mm less, but also a tiny difference.

The far more significant numbers, I'd suggest, are the piston bounce distance (at pellet exit) - the 22s piston has bounced back 7.7mm, the 25s only 5.9 Still not a huge difference, but definitely the most significant so far. Max piston bounce (ie after the pellet has left) is also a fair bit great too...



Maybe this is why ? Maybe we should make our 22mm pistons heavier....

Hi Jon

Is it too secret to bring along to the bash?

Might be interesting to compare yours and mine.

BB