Tuning Short Stroke Piston Seal ?

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harrympope

harrympope

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Jun 28, 2015
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richland Washington
I see what just appears like a long piston seal on ebay as a " short stroke piston"
I've never looked Into short stroking an airgun. There has To be more involved than just adding this seal.
Educate me please.

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Short stroking a piston decreases the length of travel the piston has to move during the shot cycle. This results in a faster lock time and can help with accuracy. A downside is that it can reduce velocity.

I ordered a couple of short stroke delrin spacers from TBT for an HW95 and HW97. They snap onto the piston head and then the seal is added on. Depending on the action they recommend not using too long of a spacer.
 
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There's different ways of short stroking. This is the simplest. Imo it's not the best way but it will be as Vincent10 described. I will only add that the barrel will have some slack between the initial break and when it compresses the spring. Some people don't like that.
Also the 35 is already a pretty short stroke gun. The 80 isn't terribly long by most people's standards.
 
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harrympope said:
thanks all ,those were the things that I was assuming adding length to the piston would cause.
in my feeble mind I had thougt a custom piston (longer rod to catch the sear) with a shorter cocking arm was what "short stroking " was.
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This is the other method. You shouldn't need a shorter arm with a longer latch rod. The barrels swing will be shorter as the piston will stop it early but I don't think it necessitates a shorter cocking arm. I could be wrong.
 
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RicL said:
TX200 Short stroke extension that uses a 25mm weihrauch piston seal. Eventually I will replace the standard seal with the 25mm long seal just to see what happens. Don’t have a TX yet though

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did you not listen, if you put the piston reward to short stroke it,you will get a sloppy cocking break.
There are better ways to do it.
That being said, your already buying the rooster Without the hens and have a dedicated opinion, without a coup..


Want a 12 ft lb Tx ,contact Tony Leach, don’t half ass it and listen to internet experts.
 
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A.G.R said:
did you not listen, if you put the piston reward to short stroke it,you will get a sloppy cocking break.
There are better ways to do it.
That being said, your already buying the rooster Without the hens and have a dedicated opinion, without a coup..


Want a 12 ft lb Tx ,contact Tony Leach, don’t half ass it and listen to internet experts.
Click to expand...


A.G.R.-
are you the internet expert here to listen to or just a keyboard ninja with an attitude..??
Blocked you as I have no time for arrogance
 
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RicL said:
TX200 Short stroke extension that uses a 25mm weihrauch piston seal. Eventually I will replace the standard seal with the 25mm long seal just to see what happens. Don’t have a TX yet though

View attachment 428704
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I'm not sure I'd convert the TX to Weihrauch style seal. The full span Weihrauch style seals are subject to greater thermal expansion issues. It's my understanding the TX styles are less affected by thermal expansion and is part of the reason they typically do better in FT. I'm currently trying to figure out how to convert my Weihrauchs to an AA type seal.
 
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A.G.R said:
did you not listen, if you put the piston reward to short stroke it,you will get a sloppy cocking break.
There are better ways to do it.
That being said, your already buying the rooster Without the hens and have a dedicated opinion, without a coup..


Want a 12 ft lb Tx ,contact Tony Leach, don’t half ass it and listen to internet experts.
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Try to get hold of Tony Leach....I've had zero luck.
Ran a TBT kit on my TX200 and liked it. Nothing sloppy about the cocking at all.
Since sold the gun and wish I hadn't!
 
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The long piston seal is intended to reduce power, without the slow shot cycle that results from putting in a weaker spring.

The HW 80 shoots at nearly 20 FPE stock, in the full power version. Detuning such a potent springer to 11.8 FPE for the Brits (for example) by means of a weaker spring makes the shot cycle slow. This makes the airgun more difficult to shoot well. The long piston seal reduces the power by shortening the stroke, without making the gun harder to shoot well.
 
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Mycapt65 said:
I'm not sure I'd convert the TX to Weihrauch style seal. The full span Weihrauch style seals are subject to greater thermal expansion issues. It's my understanding the TX styles are less affected by thermal expansion and is part of the reason they typically do better in FT. I'm currently trying to figure out how to convert my Weihrauchs to an AA type seal.
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I was just watching the TBT channel on YouTube.He's making a short stroke extension and putting HW piston seals on Air Arms guns claiming they are a better seal. I have no dog in the fight as I have no problems with either type.
 
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harrympope said:
I was just watching the TBT channel on YouTube.He's making a short stroke extension and putting HW piston seals on Air Arms guns claiming they are a better seal. I have no dog in the fight as I have no problems with either type.
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No problem. Everyone has their opinions. They may be a better seal in some aspects. But the Weihrauch seals do have greater thermal expansion. I suspect on that side of the pond they don't get the extreme heat and blinding sunny days like I get in Arkansas. Also thermal expansion issues are going to be more prevalent in >12 fpe guns and or guns with large diameter tubes. Non competitive shooters that shoot slowly or short sessions in temperate climates may never notice thermal expansion issues. Unfortunately I shoot for hours and it's sometimes cool in the morning and sunny and hot as hades in the afternoon here a lot of the year.

Also remember there may be some marketing involved in his statements. Where as I ain't selling anything. And I'm a big Weihrauch fan as well.
 
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Mycapt65 said:
No problem. Everyone has their opinions. They may be a better seal in some aspects. But the Weihrauch seals do have greater thermal expansion. I suspect on that side of the pond they don't get the extreme heat and blinding sunny days like I get in Arkansas. Also thermal expansion issues are going to be more prevalent in >12 fpe guns and or guns with large diameter tubes. Non competitive shooters that shoot slowly or short sessions in temperate climates may never notice thermal expansion issues. Unfortunately I shoot for hours and it's sometimes cool in the morning and sunny and hot as hades in the afternoon here a lot of the year.

Also remember there may be some marketing involved in his statements. Where as I ain't selling anything. And I'm a big Weihrauch fan as well.
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I wasn't arguing at all, but it was kind of funny. I've never heard anybody replacing Air Arms seals with HW.

How are you testing and monitoring "thermal expansion"?
 
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Mycapt65 said:
I'm not sure I'd convert the TX to Weihrauch style seal. The full span Weihrauch style seals are subject to greater thermal expansion issues. It's my understanding the TX styles are less affected by thermal expansion and is part of the reason they typically do better in FT. I'm currently trying to figure out how to convert my Weihrauchs to an AA type seal.
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Try oring seals.
 
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