I've seen the future....

[bigtoe01]

I'm sure you are right, however I've already noticed that 23mm is much more prone to combustion, presumably due to the higher pressures... I'm thinking that this will start to be a problem if you go too small, esp on .177.

On .20 & .22, not anything like such a big issue...

Briefly tried it on my .20 and it was surreal

Jon

You can over spring these smaller piston set ups very quickly, then they combust easy, im back running open gear lube with no burning at all.
The pressures are not much higher...thats already been looked into.

At 21mm the TP im using is smaller than at 23mm, the forecast for 20mm is 3mm maybe 2.9mm, spring wire dia has to come down also under 3mm.

What you using for a seal?

[Shed tuner]

Yeah, it surprising how little spring is needed...

Seal is a machined down US vortec, works great and lands soft

TP is 3.5 - 3.6mm.

Piston weight must be around 180 all up, need to check exactly...

[Lanky94]

Yeah, it surprising how little spring is needed...

Seal is a machined down US vortec, works great and lands soft

TP is 3.5 - 3.6mm.

Piston weight must be around 180 all up, need to check exactly...

Is this an 23mm HW95 Jon? I have been planning one for a while now, but will have to wait until next week to buy the tube to sleeve it down from 26mm ( hard to source here in the USA)

Did you use a TX or LGU piston, or make your own?

[bigtoe01]

Is this an 23mm HW95 Jon? I have been planning one for a while now, but will have to wait until next week to buy the tube to sleeve it down from 26mm ( hard to source here in the USA)

Did you use a TX or LGU piston, or make your own?

if you need a piece of tube cut to length...i have it, PM for details. I have a long length here.

LGU pistons I doubt will go down to 23mm, TX piston will BUT you need to take quite a bit out of the rear sear to get the trigger to work...again you can get over this if needed.

[slugger]

question lads.. im quite happy with my tx, so i want to turn my attention to my 97k [new style, bone stock]
i was wondering if i can sleeve the comp tube with something suitable and then make a basic piston to suit.......i was wondering if i could use the stock piston and turn it down to 20/22mm kinda thing [lose the piston walls altogether] so i would really just be reducing the end piece...... and then i could find a o ring head/extention to fit on the end of the piston in place of the current seal
sound do-able ?
the only issue is how to stop the piston rotating [latch rod alignment] ?
also.......
i had an idea about the sleeve that might solve the sealing issues some of you have experienced in the past.......namely to machine an o-ring section in the very end of the sleeve.....i mean the very end [so half an o-ring groove if you like] that way there would be no "lost volume" and removal would be easy if required...... perhaps locked in place with a grubscrew or 3 at the back-end of the comp tube ?

[bigtoe01]

question lads.. im quite happy with my tx, so i want to turn my attention to my 97k [new style, bone stock]
i was wondering if i can sleeve the comp tube with something suitable and then make a basic piston to suit.......i was wondering if i could use the stock piston and turn it down to 20/22mm kinda thing [lose the piston walls altogether] so i would really just be reducing the end piece...... and then i could find a o ring head/extention to fit on the end of the piston in place of the current seal
sound do-able ?
also.......
i had an idea about the sleeve that might solve the sealing issues some of you have experienced in the past.......namely to machine an o-ring section in the very end of the sleeve.....i mean the very end [so half an o-ring groove if you like] that way there would be no "lost volume" and removal would be easy if required...... perhaps locked in place with a grubscrew or 3 at the back-end of the comp tube ?

You mean like I did on my 80"s? Yes that will work, but i would just glue it in. Convert to rotating piston...83mm stroke, 22mm is more efficient than 23 BUT you may struggle to get the tube to do it, i went 25mm comp tube to go down to 22 and 21 and will do 20 as you can get 1.5mm, 2mm and 2.5mm wall tube.

The name of the game here is efficiency, also making sure the piston cocks held true and flies held true.

26mm comp tubes go down to 23mm
25mm comp tubes go down to 22,21 and 20mm
28mm (Diana) may only go down to 24mm, still searching for 2.5mm wall tube to get 23mm.

I will be converting my 440's, 52's and 54's to much smaller pistons, the already sleeved to 25mm will go down to 22mm asap, the 28's maybe down to 23 if i can get the tube. I may also do a 280 as I can use a Diana piston as they have enough meat to go down that small and still give me the shoulder to push against for cocking the gun.

Also now looking at a 23mm 95 (I have an action I can do here)

[Lanky94]

if you need a piece of tube cut to length...i have it, PM for details. I have a long length here.

LGU pistons I doubt will go down to 23mm, TX piston will BUT you need to take quite a bit out of the rear sear to get the trigger to work...again you can get over this if needed.

Thanks Tony.

I will PM you when back in the UK next week about the tube.

[slugger]

keep me updated about the 95 tony. my 98 needs [at the very least] shortstroking, but preferably sleeving too.. come up with a nice plug and play kit for us 95/98 owners

[bigtoe01]

keep me updated about the 95 tony. my 98 needs [at the very least] shortstroking, but preferably sleeving too.. come up with a nice plug and play kit for us 95/98 owners

The issue for break barrels is you still need a piston tube, the ideal set up is rotating so the OD has to be small, like 21mm dia, this means going smaller on spring and the reduced OD means they are stiffer, so you then go thinner wire...and right now i have no data on what is best.
None rotating will still be nice and would allow for 22.8mm piston body, new style shoe to push it all back to cock etc.

Im actually thinking of converting a 95 or Diana 34 action to fixed barrel underlever...smaller, lighter, more efficient, now i know what I need from the piston I know I have the room i need from those actions.

[slugger]

well due to lack of workshop/lathe [theres only so much i can do with a cordless-spinning-a-piston and hand tools] i am still hoping one of you guys comes up with a drop-in kit for the 97 and 95/98 .
for the 95/98 i think a piston extention to short stroke and tophat/guide would be a good starter kit [put my name down for one please] . and for the 97 a pre-made sleeve [ready to self install] a smaller diameter piston [new latch rod for rotating purposes] and maybe a new trigger sear if needed, again with guides as an option. put me down for one of those too

[RichardH]

Awesome! What sort of lube should it have, and how much?

She said that too!

[snock]

She said that too!

Mmmmm... slippery...

[Shed tuner]

The idea of a "drop in kit" for sleaved down comp tubes is not good IMHO - far too much to go wrong.

Best thing with comp tube guns is an exchange basis, i.e. send in entire powerplant, and get a sleaved down one back, exactly as venom/vmac did for the ultraglide conversion.

[slugger]

The idea of a "drop in kit" for sleaved down comp tubes is not good IMHO - far too much to go wrong.

Best thing with comp tube guns is an exchange basis, i.e. send in entire powerplant, and get a sleaved down one back, exactly as venom/vmac did for the ultraglide conversion.

works for me

[Black Beard]

A HW 25 spring mght be just about right with those little pistons if the data on the spring thread is right.