GTA

All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => UK Airgun Gate => Topic started by: Nitrocrushr on February 17, 2018, 03:42:57 PM

Title: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 17, 2018, 03:42:57 PM
As promised, here is a quick overview of the 22mm Skirtless Conversion from Tony Leach.  I received my kit this past week and installed it this morning in my TX200HC .177. 

Here are some pictures showing what is included in the kit, and some comparisons to the stock components.

First off, Tony does not yet sell compression tubes, but at some point is planning on it.  All he needs in order to manufacture his conversion kit for you is a stock MK3 compression tube.  Tony supplied the threaded piston rod and the spring.


Included in the kit is;

MK3 compression tube, sleeved to 22mm

Skirtless Piston - includes a 22mm non-parachute style main seal, similar to the Vortek Vac-Seal

Tony manufactures his own threaded piston rods and they are Nitrided, making them stronger than the factory AA rods

The spring is a TX200 MK3 sub-12fpe.  I measured this spring and it is .115" (2.94mm) diameter wire - thinner than my previous JM QX4600, which is .120", and much thinner than the factory .130" spring

Also included are several spacers of various thickness so you can fine tune to the energy you are looking for, and a small container of Moly 70% WS2.  This is Tony's own blend that he mixes himself.

Tony tests each kit in his own rifle before sending them off to customers, making sure that he is able to achieve a minimum of 11 fpe

Here is the completed kit as it arrived;

(http://i63.tinypic.com/bip7wi.jpg)


Here are some comparisons of the stock piston to the 22mm skirtless piston

(http://i65.tinypic.com/2ag6jo2.jpg)

(http://i66.tinypic.com/1xz3w2.jpg)



Comparison between the factory compression tube and the 22mm sleeved compression tube

(http://i63.tinypic.com/dyrhxv.jpg)


The 22mm sleeve is cross hatched like the factory compression tube

(http://i67.tinypic.com/2rze5u8.jpg)


Comparisons between the factory compression tube/piston assembly and the 22mm Conversion

(http://i65.tinypic.com/28w13rd.jpg)

(http://i65.tinypic.com/24bohh2.jpg)


The 22mm Conversion reduces the stroke to 90mm.  As a result, the rifle now only used the first 2 notches of the compression tube.  This is barely noticeable when cocking the rifle.  As you can see in the comparisons below, the difference in cocking handle position when the rifle is cocked is minimal;

Handle position with the full stroke from the factory

(http://i67.tinypic.com/20fp7ki.jpg)



Handle position on the 22mm Conversion


(http://i64.tinypic.com/24e80af.jpg)



I ran about 100 shots through it so far, and this kit is already giving single digit Extreme Spread, and it is perfectly balanced.  Both the JSB 7.87's and the 8.44's are coming out with the exact same fpe;

JSB Express 7.87
Weighed at 7.90 grains
799fps
11.20fpe

JSB Exact Diabolo 8.44
Weighed at 8.44 grains
773fps
11.20fpe


It was too windy to do any good outdoor testing, but here is a quick 5-shot group at 20 yards

(http://i67.tinypic.com/21ah2jm.jpg)


In summary I will say that this 22mm conversion makes a big difference in the overall smoothness of this rifle.  It is easier to cock, and much smoother on the shot with greatly reduced recoil. 

From the factory the rifle had a powerful jump to it.  When I tuned it down to 11.3fpe with the JM QX4600 spring it reduced recoil and smoothed it out quite a bit.  Switching to this 22mm Conversion kit took this even further.  It is now putting out the same energy with a thinner spring, MUCH lighter piston, and reduced stroke.  Cocking effort and recoil reduced even more ;)

Comparing this kit to the way the rifle came from the factory would be like night and day, just no comparison 8)

I will continue to put this kit through the paces outdoors.  For now I will leave it set for 11.2 fpe, but final decision on that will come after I can stretch it out a little more outdoors 8)

(http://i67.tinypic.com/2eakqbp.jpg)



If anyone is interested in learning more about the 22mm skirtless conversion, you can reach out to Tony Leach on his FB group "Airguntech", or in the group "Lost Volume"

https://www.facebook.com/airguntech/


https://www.facebook.com/groups/1447138175311176/


Also on his blog;

https://www.airguntech.com


Tony has been very helpful in answering all of my questions, and I am very pleased with his work 8)





Steve

Title: Re: 22mm Skirtless Conversion
Post by: broachoski on February 17, 2018, 04:18:15 PM
Thanks for such a great detailed presentation Steve.
Title: Re: 22mm Skirtless Conversion
Post by: AmBraCol on February 17, 2018, 04:38:57 PM
Thanks for posting this.  Fascinating.  His blog's not been posted to since 2013, however...

The Lost Volume group looks interesting, don't know if they'll OK my joining or not.  Look forward to learning more about the concept and execution.

https://www.facebook.com/groups/1447138175311176/ (https://www.facebook.com/groups/1447138175311176/)
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on February 17, 2018, 05:58:40 PM
Thank you for the detailed report and the great pictures!  I'm looking forward to hearing more.  BTW, how do you always get those amazing groups?  Are you using a bag, rest, bipod, etc.?
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 17, 2018, 06:49:18 PM
You're welcome guys ;D

Paul - Thank you for posting the link to "Lost Volume".  I was running out of time when I first posted this and forgot to include that link.  I revised my post and now have it included at the bottom.  Lots of great discussions in that group, much to learn 8)
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 17, 2018, 06:51:33 PM
Thank you for the detailed report and the great pictures!  I'm looking forward to hearing more.  BTW, how do you always get those amazing groups?  Are you using a bag, rest, bipod, etc.?

Hi Zack, Nothing special.....I use a single caldwell bag placed at the balance point.  Shifting the rifle back and forth about 1/4" at a time will eventually show you the sweet spot for a given rifle ;)

Steve
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on February 17, 2018, 09:28:12 PM
Thank you for the detailed report and the great pictures!  I'm looking forward to hearing more.  BTW, how do you always get those amazing groups?  Are you using a bag, rest, bipod, etc.?

Hi Zack, Nothing special.....I use a single caldwell bag placed at the balance point.  Shifting the rifle back and forth about 1/4" at a time will eventually show you the sweet spot for a given rifle ;)

Steve

Man, you must have your springers shooting ultra smooth.  None of mine shoot particularly well off a bag/rest.  If I put a folded towel over the bag, and support the butt of the rifle absolutely the same each shot, I can get nice groups.  It's hard to be consistent though.
Title: Re: 22mm Skirtless Conversion
Post by: Yogi on February 17, 2018, 10:07:50 PM
What a beauty and beautifully chronicled!  Thank you. :-*

Did you get a chance to weight the different pistons before you put them it.  I'm assuming that the weight the you took out of the piston is almost matched by the increased weight of the sleeved compression tube.  Of course one is moving and the other is not.

-Y
Title: Re: 22mm Skirtless Conversion
Post by: Paul E on February 18, 2018, 12:04:55 AM
Really looking forward to your outcome when you stretch that target out to 50 yards and let the lead fly. Talked to Tony on lost volume and he said the kit works well in .22 which is what I have.
Thanks, Butch
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 18, 2018, 11:43:36 AM
What a beauty and beautifully chronicled!  Thank you. :-*

Did you get a chance to weight the different pistons before you put them it.  I'm assuming that the weight the you took out of the piston is almost matched by the increased weight of the sleeved compression tube.  Of course one is moving and the other is not.

-Y

The only scale I have is a small one for weighing pellets, so I was unable to compare the two from a weight perspective.  I would say you are close when you mentioned the weight saved on the piston is cancelled out by the sleeved compression tube.  But having the weight off this piston totally transforms the rifles ;D

Steve
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 18, 2018, 12:01:24 PM
I was rushed for time yesterday when I posted my overview and forgot to mention the thickness of the included spacers.  They are as follows;

4.14mm
3.22mm
2.47mm
2.26mm

This gives you a nice range to fine tune to your desired sub 12 energy level. 

This morning I did some more experimenting and removed the 4.14mm spacer I had installed, replacing it with the thinnest 2.26mm spacer.  The result was as follows;

Before
4.14mm spacer
11.20 fpe

After
2.26mm spacer
10.84 fpe

This equates to about 0.19 fpe per mm of preload

Based on some previous tuning with the factory pistons, as you start to drop into the sub 11 fpe range, the weight of the factory piston becomes more apparent, slowing down the shot cycle.  The rifle feels smooth, but shot cycle is slow and can make the rifle finicky on target, actually tougher to maintain the tiny little groups consistently....so you speed the shot cycle back up, into the 11 fpe range to get your consistency back.

With this small diameter, lightweight 22mm set-up, you can drop into the sub 11fpe category and still have an extremely fast shot cycle.  This little piston is quick! 8)  What this means is that you can continue to soften the shot, while maintaining the quick shot cycle.  On target this means it is easier to hold those tiny little groups ;)

Here is a 10-shot group at 20 yards.  Yes you still have to do your part with good form, breathing, etc.....but this group was in no way difficult.  One shot after the other was dropping right into this tiny little hole 8) The more I shoot this rifle, the more impressed I am with this 22mm kit.  I am going to let it right where it is and just shoot ;D

(http://i65.tinypic.com/egqs1h.jpg)



Steve
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on February 18, 2018, 01:07:19 PM
As usual, very impressive shooting Steve.  And thank you for posting the energy level per mm of preload, that's helpful.
Title: Re: 22mm Skirtless Conversion
Post by: Sfttailrdr46 on February 18, 2018, 01:32:23 PM
Be very sure to post when you have become bored with the TX I will be very happy to give it a loving home especially with that beautiful walnut stock
Title: Re: 22mm Skirtless Conversion
Post by: Yogi on February 19, 2018, 01:14:43 AM
I was rushed for time yesterday when I posted my overview and forgot to mention the thickness of the included spacers.  They are as follows;

4.14mm
3.22mm
2.47mm
2.26mm

This gives you a nice range to fine tune to your desired sub 12 energy level. 

This morning I did some more experimenting and removed the 4.14mm spacer I had installed, replacing it with the thinnest 2.26mm spacer.  The result was as follows;

Before
4.14mm spacer
11.20 fpe

After
2.26mm spacer
10.84 fpe

This equates to about 0.19 fpe per mm of preload

Based on some previous tuning with the factory pistons, as you start to drop into the sub 11 fpe range, the weight of the factory piston becomes more apparent, slowing down the shot cycle.  The rifle feels smooth, but shot cycle is slow and can make the rifle finicky on target, actually tougher to maintain the tiny little groups consistently....so you speed the shot cycle back up, into the 11 fpe range to get your consistency back.

With this small diameter, lightweight 22mm set-up, you can drop into the sub 11fpe category and still have an extremely fast shot cycle.  This little piston is quick! 8)  What this means is that you can continue to soften the shot, while maintaining the quick shot cycle.  On target this means it is easier to hold those tiny little groups ;)

Here is a 10-shot group at 20 yards.  Yes you still have to do your part with good form, breathing, etc.....but this group was in no way difficult.  One shot after the other was dropping right into this tiny little hole 8) The more I shoot this rifle, the more impressed I am with this 22mm kit.  I am going to let it right where it is and just shoot ;D

(http://i65.tinypic.com/egqs1h.jpg)

Steve

Steve,

You have proven once again that "less is more"!  I would not want to have to face you in Hunter FT. :D

-Y
Title: Re: 22mm Skirtless Conversion
Post by: Pappy on February 19, 2018, 09:58:49 AM
Steve ....nice work .... and review .... and as always, proven with springers ..... "SPEED KILLS".
 ;D

Pappy / Allan
Title: Re: 22mm Skirtless Conversion
Post by: DanT on February 20, 2018, 11:38:19 PM
Steve,

Glad to see a one of these conversion's make it over! You stepped in it so all the pressure is on you! lol

What type, where and how much lube to did you end up using on the conversion? Any chance of a video showing the difference in shot cycle between your factory tune and short stroked skirt less? Also curious to see how a stronger spring or more pre-load effects shot cycle and performance. Maybe not much to gain due to the working volume?

Regards,

DT
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 21, 2018, 10:11:34 PM
Steve,

Glad to see a one of these conversion's make it over! You stepped in it so all the pressure is on you! lol

What type, where and how much lube to did you end up using on the conversion? Any chance of a video showing the difference in shot cycle between your factory tune and short stroked skirt less? Also curious to see how a stronger spring or more pre-load effects shot cycle and performance. Maybe not much to gain due to the working volume?

Regards,

DT


Hi Dan, Tony ships the kit fully lubed, along with a small container of his own blend of moly 70.  However, I scrubbed everything up for pictures and used the lube that I have found to work best in my rifles, which was the Vortek Moly 70+.  At some point I will test the lube that Tony shipped with the kit.  I burnished a small amount into the walls of the comp tube as far down as I could reach, then smeared a tiny bit around the edge of the main seal, making sure not to get any in front of the seal.  I also smeared a light film on the piston rod, and onto the spring guide.  Outside of spring was smeared with a very light film of moly as well.  Being that there is no skirt, it is important not to mix any lubes...if moly, then moly all the way ;)

I would like to do a video with a measurable demonstration of the recoil differences between a stock rifle and this kit.  I can tell you the difference is substantial.  The difference in cocking effort is also substantial.  Comparing it to the recoil after I had tuned it down to 11.3fpe with the JM QX4600 spring was also a very noticeable improvement.

Tony would have to answer questions regarding heavier springs and this kit.  How far could you push the energy levels with the skirtless?  I don't know.  I could easily push 12 fpe with this kit and the spacers provided.

Steve
Title: Re: 22mm Skirtless Conversion
Post by: Pappy on February 22, 2018, 08:20:35 AM
We all know ..... the BEST lube is a 60/40 blend of Moly 70+ and KRYTOX!  Stir the two together until you get an oatmeal consistency, which won't take long.  Apply a liberal amount ..... shoot until the piston actually seizes!!!!!!!!!!

OF COURSE, I AM KIDDING!!!!

Not kidding ..... never use Krytox on an airgun, and never let it come in contact with another lube ..... it doesn't play nice with any kind of lube.

Pappy / Allan
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 22, 2018, 09:02:41 PM
We all know ..... the BEST lube is a 60/40 blend of Moly 70+ and KRYTOX!  Stir the two together until you get an oatmeal consistency, which won't take long.  Apply a liberal amount ..... shoot until the piston actually seizes!!!!!!!!!!

OF COURSE, I AM KIDDING!!!!

Not kidding ..... never use Krytox on an airgun, and never let it come in contact with another lube ..... it doesn't play nice with any kind of lube.

Pappy / Allan

Pay no attention to that man behind the curtain ;D
Title: Re: 22mm Skirtless Conversion
Post by: DanT on February 22, 2018, 10:23:58 PM
Steve,

Glad to see a one of these conversion's make it over! You stepped in it so all the pressure is on you! lol

What type, where and how much lube to did you end up using on the conversion? Any chance of a video showing the difference in shot cycle between your factory tune and short stroked skirt less? Also curious to see how a stronger spring or more pre-load effects shot cycle and performance. Maybe not much to gain due to the working volume?

Regards,

DT


Hi Dan, Tony ships the kit fully lubed, along with a small container of his own blend of moly 70.  However, I scrubbed everything up for pictures and used the lube that I have found to work best in my rifles, which was the Vortek Moly 70+.  At some point I will test the lube that Tony shipped with the kit.  I burnished a small amount into the walls of the comp tube as far down as I could reach, then smeared a tiny bit around the edge of the main seal, making sure not to get any in front of the seal.  I also smeared a light film on the piston rod, and onto the spring guide.  Outside of spring was smeared with a very light film of moly as well.  Being that there is no skirt, it is important not to mix any lubes...if moly, then moly all the way ;)

I would like to do a video with a measurable demonstration of the recoil differences between a stock rifle and this kit.  I can tell you the difference is substantial.  The difference in cocking effort is also substantial.  Comparing it to the recoil after I had tuned it down to 11.3fpe with the JM QX4600 spring was also a very noticeable improvement.

Tony would have to answer questions regarding heavier springs and this kit.  How far could you push the energy levels with the skirtless?  I don't know.  I could easily push 12 fpe with this kit and the spacers provided.

Steve

Thanks Steve. Sounds like a very nice set up. Keep us posted as you break it in.

By the way..was the TP changed at all with this conversion?

Regards,

Dan
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on February 23, 2018, 05:04:09 AM

Thanks Steve. Sounds like a very nice set up. Keep us posted as you break it in.

By the way..was the TP changed at all with this conversion?

Regards,

Dan

Yes, Tony reduces TP length on his conversions.  He machines them down by 3mm.  This increases velocity by 40fps with the same swept volume on JSB Express 7.9. 
Title: Re: 22mm Skirtless Conversion
Post by: TheBman on March 23, 2018, 07:41:13 PM
Yeah, I gotta do this Steve. Thanks for the write up and info.
Title: Re: 22mm Skirtless Conversion
Post by: DanT on October 06, 2018, 09:51:17 PM
Its been a long wait but I finally got my 22mm conversion parts in from Tony Leach. He was doing the mods on customer supplied comp tubes when Nitrocrusher got his but has come up with a DIY kit. This is going into my Walnut TX200 HC .177. Wanting to keep the factory components so I could go back to FAC as needed I ordered a spare comp tube from PA for this conversion. Tony supplied the threaded sleeve, rod, piston, delrin spring guide and spacers.  Note that his parts will only fit the 15mm ID AA 16J (12ft/lb) spring. I ordered mine from PA. They will not fit the FAC spring as supplied by AA and he does not recommend using a FAC spring for this conversion. Apparently this is a Mk2 type spring with a 14mm ID.

To install:

1. Remove the comp tube threaded on TP nut. Mine took some heat.
2. Clean up threads and install threaded sleeve with removable loctite.
3. Loctite (permanent) in the threaded rod on the piston head. With Tony's rod it will be flush with the piston top. If you re-use the factory rod it will be below the piston head by a few mm's. This is to reduce the stroke.
4. Lightly lube all the parts and install guide rod and spring. I used krytox 205. One 3mm spacer on back of rod.

Enjoy a crazy soft and quick shot cycle @ 800fps with 8.4 AA 4.52 pellets. I could probably pull the spacer and get it under 12ft/lbs but it's shooting really good at the moment. Significantly less mass and movement. This really takes the TX to the next level IMHO.


(https://i.imgur.com/b100Sbz.jpg) (https://i.imgur.com/Rct66o4.jpg)(https://i.imgur.com/ProuvjC.jpg)
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on October 06, 2018, 10:09:11 PM
Very nice write-up Dan 8) I see you have the new double seal as well.  Testing has shown that this minimizes velocity variation due to temperature change.

Nice work!  I couldn’t agree with you more.  The 22mm conversion makes a huge difference ;)

Steve
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on October 06, 2018, 11:02:31 PM
Is this available for an HW97?  Also, about how much does this conversion cost?
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on October 07, 2018, 10:53:59 AM
Is this available for an HW97?  Also, about how much does this conversion cost?

Not yet.  Tony is currently working on a 23mm conversion for the HW97K.

Steve
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on October 07, 2018, 11:37:37 AM
Is this available for an HW97?  Also, about how much does this conversion cost?

Not yet.  Tony is currently working on a 23mm conversion for the HW97K.

Steve

Thanks Steve.  Now that you've had this for awhile, how are you liking it?  Do you still find that there is less hold sensitivity?  I'm hoping that one of these kits in a heavy laminate stock should reduce the hold sensitivity a significant amount in an HW97.
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on October 07, 2018, 03:17:37 PM
Is this available for an HW97?  Also, about how much does this conversion cost?

Not yet.  Tony is currently working on a 23mm conversion for the HW97K.

Steve

Thanks Steve.  Now that you've had this for awhile, how are you liking it?  Do you still find that there is less hold sensitivity?  I'm hoping that one of these kits in a heavy laminate stock should reduce the hold sensitivity a significant amount in an HW97.

I was really impressed with it Zack.  It does a few things;

Reduces mass due to the lightened piston - less recoil
Reduces stroke - shorter shot cycle; but not so short as to make the rifle jumpy
Speeds up shot cycle (very quick) - lower lock time equals less hold sensitivity
Tony works the transfer port also.  It is extremely efficient, with almost no wasted energy.

From what I understand, Tony is going to lengthen the stroke on the 97K kit a little bit.  This will soften it up a little.  The 97K is rather short on stroke (I think they are around 81mm with a heavy 26mm diameter piston).  While too long of a stroke makes for a sluggish shot cycle, too short can make a rifle buck a bit on the shot.  Getting the stroke just right for the piston diameter and total volume is what Tony goes after on his conversion kits.  The end result is a quick, smooth shot with minimal jump.

I just sold my 22mm TX200HC in preparation for another project ;)  Tony Leach is now offering a 200g lightened piston with a dual seal that shortens the TX/PS stroke by 5mm.  I am planning to either try that, or get another 22mm skirtless conversion with his new dual seal set-up that you see pictured in Dan's post above.

Steve
 
Title: Re: 22mm Skirtless Conversion
Post by: PiterM on October 07, 2018, 04:04:49 PM
Most impressive!
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on October 07, 2018, 06:54:17 PM
Thanks for the detailed information! I'm looking forward to your next project.
Title: Re: 22mm Skirtless Conversion
Post by: DanT on October 08, 2018, 06:45:50 PM
Is this available for an HW97?  Also, about how much does this conversion cost?

 Pretty cool to have something new in the airgun world that hasn't been done before and disrupts conventional thinking. I see this as being a factory option by some OEM down the road. PM me for pricing info. I know he is currently out of conversions but expecting more in soon.
Very nice write-up Dan 8) I see you have the new double seal as well.  Testing has shown that this minimizes velocity variation due to temperature change.

Nice work!  I couldn’t agree with you more.  The 22mm conversion makes a huge difference ;)

Steve

Thanks Steve. Really enjoying this conversion. Not often we can get something this cutting edge in the springer community. Looking forward to that HW97 kit too.  ;)

I am still tickling 12ft/lbs with 8.4gr using a 3mm spacer but you couldn't tell by the shot cycle. It also seems to really reduce hold sensitivity.

Regards,

Dan
Title: Re: 22mm Skirtless Conversion
Post by: DanT on October 08, 2018, 07:03:16 PM
Is this available for an HW97?  Also, about how much does this conversion cost?

Not yet.  Tony is currently working on a 23mm conversion for the HW97K.

Steve

Thanks Steve.  Now that you've had this for awhile, how are you liking it?  Do you still find that there is less hold sensitivity?  I'm hoping that one of these kits in a heavy laminate stock should reduce the hold sensitivity a significant amount in an HW97.

I was really impressed with it Zack.  It does a few things;

Reduces mass due to the lightened piston - less recoil
Reduces stroke - shorter shot cycle; but not so short as to make the rifle jumpy
Speeds up shot cycle (very quick) - lower lock time equals less hold sensitivity
Tony works the transfer port also.  It is extremely efficient, with almost no wasted energy.

From what I understand, Tony is going to lengthen the stroke on the 97K kit a little bit.  This will soften it up a little.  The 97K is rather short on stroke (I think they are around 81mm with a heavy 26mm diameter piston).  While too long of a stroke makes for a sluggish shot cycle, too short can make a rifle buck a bit on the shot.  Getting the stroke just right for the piston diameter and total volume is what Tony goes after on his conversion kits.  The end result is a quick, smooth shot with minimal jump.

I just sold my 22mm TX200HC in preparation for another project ;)  Tony Leach is now offering a 200g lightened piston with a dual seal that shortens the TX/PS stroke by 5mm.  I am planning to either try that, or get another 22mm skirtless conversion with his new dual seal set-up that you see pictured in Dan's post above.

Steve

Just went back and looked at your piston. I now see that it did not have the O ring. Good to see he is improving on the design. Tony also mention that the 97K piston rod sear catch can be a challenge to get oriented correctly.  TX has non directional engagement where the 97K is directional with the hook down I believe. It will have to have some form of quide/slot to keep the hook from rotating. Looking forward to that one.

I am also interested in something for my LGU but I recall Tony not liking the barrel lead in chamfer from the factory. He said it is not conducive to a lost volume conversion unless it is modified to act on the pellet skirt. This provides a better seal and contributes to velocity. Cool stuff.

Interesting times in springer land!

Regards,

Dan
Title: Re: 22mm Skirtless Conversion
Post by: Yogi on October 08, 2018, 09:27:24 PM


Good stuff!
Thanks for posting it. :D

-Y
Title: Re: 22mm Skirtless Conversion
Post by: Hielke on October 09, 2018, 05:20:35 AM
Am I reading this correctly regarding the 22mm TX200 conversion. Is the Tony Leach piston with the piston rod only 130 grams?
Title: Re: 22mm Skirtless Conversion
Post by: DanT on October 09, 2018, 11:10:06 AM
Am I reading this correctly regarding the 22mm TX200 conversion. Is the Tony Leach piston with the piston rod only 130 grams?

A little more...I weighed mine at 147g vs 219g for the factory TX piston. Add in the "hunky" factory AA top hat and the factory piston is 242g. Most remove it when tuning with a new delrin top hat so 219g is a good number.

My TX out of the box was shooting 8.4g @ 900fps. Pretty hot with the heavy AA set up.

Regards,

DT
Title: Re: 22mm Skirtless Conversion
Post by: Hielke on October 10, 2018, 11:24:13 AM
Thnx Dan, think I will be ordering a set as well.
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on October 11, 2018, 12:18:46 PM

You guys really have me reconsidering the HW97 and going for a TX200.  Really, the power level that you got with his kit is exactly where I would want to be.  I really liked my HW97 at about 11fpe.  Having this amount of energy with the shot cycle improvements from Tony's kit sounds like a dream.
Title: Re: 22mm Skirtless Conversion
Post by: TonyL on December 05, 2018, 09:23:12 PM
Gents

I see a few of you guys are getting interested in my 22mm conversion...if you can get your head around my accent i have produced a few short video's in the AVE and This old Tony stylee to help you ;)

have a look round my YT channel, you can search for Tony Leach on YT, there is a pic of me wearing a bobby hat and i have a white beard...click that and you will get links to video's about the 22mm conversion

I'm hoping the video's for now answer most questions...

Please remember, this kit was designed for sub12fpe use, it will deliver more BUT it has not been designed to, however running a .22 set up with a .177 kit/spring set up is probably very safe ;) Over springing the kits is VERY easy to do, the kit is designed to work with the OEM 16j /12fpe AirArms mk3 spring ONLY...stifffer springs will break the rear guide...don't push the kits to do what they are not designed to do ;) Running a full length Mk3 12fpe AA spring is to much... trust me i know!

I will do my best to drop by, or you can get me on my Lost Volume facebook group of message me on my Airguntech facebook page...

Tony

Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on December 05, 2018, 09:30:17 PM
Hi Tony, Welcome to the GTA forum ;D

For those who are considering a 22mm conversion, Tony has some very helpful info on the following site;

https://www.youtube.com/user/ocztony (https://www.youtube.com/user/ocztony)


Steve
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on December 05, 2018, 10:26:32 PM
Gents

I see a few of you guys are getting interested in my 22mm conversion...if you can get your head around my accent i have produced a few short video's in the AVE and This old Tony stylee to help you ;)

have a look round my YT channel, you can search for Tony Leach on YT, there is a pic of me wearing a bobby hat and i have a white beard...click that and you will get links to video's about the 22mm conversion

I'm hoping the video's for now answer most questions...

Please remember, this kit was designed for sub12fpe use, it will deliver more BUT it has not been designed to, however running a .22 set up with a .177 kit/spring set up is probably very safe ;) Over springing the kits is VERY easy to do, the kit is designed to work with the OEM 16j /12fpe AirArms mk3 spring ONLY...stifffer springs will break the rear guide...don't push the kits to do what they are not designed to do ;) Running a full length Mk3 12fpe AA spring is to much... trust me i know!

I will do my best to drop by, or you can get me on my Lost Volume facebook group of message me on my Airguntech facebook page...

Tony

Thank you Tony - these videos should be super informative!  I look forward to getting my kit.  (I'm the guy who's been bugging you with all of the questions throughout the day.  ;D)

Edit:  I just got finished watching the videos and, YES, they are very helpful - THANK YOU!
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on December 06, 2018, 02:14:02 PM
I ordered the parts last night from Tony.  He was super helpful in answering all of my questions, and has already shipped the parts :o  I can't wait to give them a shot.  Of course, there is that small issue that I don't yet own a TX200.  I hope to get one soon.  In the meantime, another member has offered to let me shoot the holy grail of TX200/22mm conversions, and I hope to take him up on that!  That should let me know what perfection feels like, and will give me something to work towards as I tune my rifle.
Title: Re: 22mm Skirtless Conversion
Post by: TonyL on December 06, 2018, 02:43:03 PM
I ordered the parts last night from Tony.  He was super helpful in answering all of my questions, and has already shipped the parts :o  I can't wait to give them a shot.  Of course, there is that small issue that I don't yet own a TX200.  I hope to get one soon.  In the meantime, another member has offered to let me shoot the holy grail of TX200/22mm conversions, and I hope to take him up on that!  That should let me know what perfection feels like, and will give me something to work towards as I tune my rifle.

Now thats dedication, orders a conversion and does not even own the rifle ;)

get on to PA and get an order in, make sure they check the barrel for rust first though ;)
Title: Re: 22mm Skirtless Conversion
Post by: Yogi on December 07, 2018, 02:18:42 PM


Yes, Tony reduces TP length on his conversions.  He machines them down by 3mm.  This increases velocity by 40fps with the same swept volume on JSB Express 7.9.

By reducing the TP by 3mm does he not increase the stroke? :-\  Or does the new piston nose reduce the stroke by 6mm?

-Y
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on December 07, 2018, 08:05:09 PM


Yes, Tony reduces TP length on his conversions.  He machines them down by 3mm.  This increases velocity by 40fps with the same swept volume on JSB Express 7.9.

By reducing the TP by 3mm does he not increase the stroke? :-\  Or does the new piston nose reduce the stroke by 6mm?

-Y

The 3mm reduction in Transfer Port length does not affect the stroke, it just improves the efficiency with the 22mm set-up.  The reduction in stroke length comes from the total length from front of main seal to the end of the piston rod.  The shorter this length is, the longer the stroke, the longer this length...the shorter the stroke ;)

Steve

Steve
Title: Re: 22mm Skirtless Conversion
Post by: TonyL on December 11, 2018, 09:25:54 AM


Yes, Tony reduces TP length on his conversions.  He machines them down by 3mm.  This increases velocity by 40fps with the same swept volume on JSB Express 7.9.

By reducing the TP by 3mm does he not increase the stroke? :-\  Or does the new piston nose reduce the stroke by 6mm?

-Y


The piston nose sits on the rod 4mm further out, the seal then sits a further 3mm past this so effectively now the stroke is reduced by 7 to 8mm.
The TP length is reduced by 3mm so this adds 3mm stroke back on.

so lets call it 5mm off the stoke, which means the conversion runs 93mm stroke.

All depends on that piston nose to rod fit...most come out between 4 to 5mm.

Title: Re: 22mm Skirtless Conversion
Post by: DanT on December 20, 2018, 10:28:20 PM
This conversion is awesome and glad to see Tony on GTA. Once you get your TX you will not be disappointed.

Merry Christmas air gunners!

Cheers!

Dan
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on January 11, 2019, 12:27:50 PM
Have any of you tested this kit at different temperatures and elevations?  I'm just curious how much it is affected by these variables.  It will be another month before I have a chance to check these things out, so I thought I'd throw the question out there...

Thanks!
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on January 11, 2019, 07:25:31 PM
One more question...  Is anyone else noticing that their barrel is fouling quickly?  Attached is an image of some cleaning patches that I pulled through the barrel after only 25 shots with FTT's going at 770 fps.  I'd like to know if the barrel is fouling so quickly since a brushed it so heavily with a brass brush and J-B Bore paste (to remove the rust) or if this is just a result of the higher pressure that the 22mm piston kit creates.  No exaggeration - the barrel was aggressively brushed for probably 5 - 10 minutes a session 3 different times.  It does get clean after only 4 patches, but my other rifles would need to be shot at least 100 times in order to produce the first patch that is this dirty.

Thanks!
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on January 13, 2019, 04:48:27 PM
Have any of you tested this kit at different temperatures and elevations?  I'm just curious how much it is affected by these variables.  It will be another month before I have a chance to check these things out, so I thought I'd throw the question out there...

Thanks!

Zack, I ran a test on my 22mm dual seal conversion today.   Outdoor temperature was 27 degrees with a light breeze.  I ran about 5 shots over the chronograph straight off the rack at room temperature, which was about 70 degrees.  I then set the rifle outside on a sandbag in the fresh snow - 27 degrees for 1 hour.

(https://i.imgur.com/kWsBeAT.png)


After the rifle sat outside for an hour, I quickly ran 5-6 shots over the chronograph straight from the outside.

TX200 Rifle - .177 caliber - Tony Leach 22mm conversion kit (dual seal)
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.86 grains - 806 fps - 11.34 fpe

Outdoors - 27 degrees for 1 hour
JSB 7.87
Pellet weighed at 7.88 grains - 816 fps - 11.65 fpe

2.7% increase in energy

Next, I swapped power plants and ran the exact same test using my standard sub-12 fpe tune with the Maccari Tesla MK2 seal

TX200 Rifle - .177 caliber - with factory piston, JM Ultra XLD, Maccari Tesla MK2 main seal
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.90 grains - 810 fps - 11.51 fpe

Outdoors - 27 degrees for 1 hour
Pellet weighed at 7.86 grains - 835 fps - 12.17 fpe

5.5% increase in energy


While the dual seal design helps to reduce the variation due to temperature changes, as with any springer there is still some variation.  In a spring piston air rifle I think you will always see variation with temperature change.

On the positive side, the amount of variation was 51% less than the hand fitted JM Tesla MK2 seal 8)

This summer I can do some comparisons in the summer heat.

Steve
Title: Re: 22mm Skirtless Conversion
Post by: nced on January 13, 2019, 05:03:53 PM
Have any of you tested this kit at different temperatures and elevations?  I'm just curious how much it is affected by these variables.  It will be another month before I have a chance to check these things out, so I thought I'd throw the question out there...

Thanks!

Zack, I ran a test on my 22mm dual seal conversion today.   Outdoor temperature was 27 degrees with a light breeze.  I ran about 5 shots over the chronograph straight off the rack at room temperature, which was about 70 degrees.  I then set the rifle outside on a sandbag in the fresh snow - 27 degrees for 1 hour.

(https://i.imgur.com/kWsBeAT.png)


After sitting outside for an hour, I grabbed the rifle and quickly ran 5-6 shots over the chronograph straight from the outside.

TX200 Rifle - .177 caliber - Tony Leach 22mm conversion kit (dual seal)
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.86 grains - 806 fps - 11.34 fpe

Outdoors - 27 degrees for 1 hour
JSB 7.87
Pellet weighed at 7.88 grains - 816 fps - 11.65 fpe

2.7% increase in energy

Next, I swapped power plants and ran the exact same test using my standard sub-12 fpe tune with the Maccari Tesla MK2 seal

TX200 Rifle - .177 caliber - with factory piston, JM Ultra XLD, Maccari Tesla MK2 main seal
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.90 grains - 810 fps - 11.51 fpe

Outdoors - 27 degrees for 1 hour
Pellet weighed at 7.86 grains - 835 fps - 12.17 fpe

5.5% increase in energy


While the dual seal design helps to reduce the variation due to temperature changes, as with any springer there is still some variation.  In a spring piston air rifle I think you will always see variation with temperature change.

On the positive side, the amount of variation was 50% less than the hand fitted JM Tesla MK2 seal 8)

This summer I can do some comparisons in the summer heat.

Steve

When I moved to North Carolina a decade ago I did a similar test using my .177 R9, oring sealed piston cap, and Krytox GPL205 lube. I left the R9 in my sunroom over night when the temp dropped to the 20s and shot a few CPLs over the chrony. A couple days later I left the gun indoors and chronied the gun in temps of mid 60s. I don't remember the exact velocity (I wasn't shooting sup 12fpe) but the velocity only varied 10fps between the two temps. I was surprised to find that the higher velocity was shot in the lower temp rather than the higher temp. While 10fps is such a minor variation that it could have simply been due to "atmospheric conditions" like humidity, or maybe even pellet weight variations. Anywhoo......I do think that perhaps denser cooler air being compressed affects the velocity.
Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on January 13, 2019, 05:12:15 PM
Have any of you tested this kit at different temperatures and elevations?  I'm just curious how much it is affected by these variables.  It will be another month before I have a chance to check these things out, so I thought I'd throw the question out there...

Thanks!

Zack, I ran a test on my 22mm dual seal conversion today.   Outdoor temperature was 27 degrees with a light breeze.  I ran about 5 shots over the chronograph straight off the rack at room temperature, which was about 70 degrees.  I then set the rifle outside on a sandbag in the fresh snow - 27 degrees for 1 hour.

(https://i.imgur.com/kWsBeAT.png)


After the rifle sat outside for an hour, I quickly ran 5-6 shots over the chronograph straight from the outside.

TX200 Rifle - .177 caliber - Tony Leach 22mm conversion kit (dual seal)
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.86 grains - 806 fps - 11.34 fpe

Outdoors - 27 degrees for 1 hour
JSB 7.87
Pellet weighed at 7.88 grains - 816 fps - 11.65 fpe

2.7% increase in energy

Next, I swapped power plants and ran the exact same test using my standard sub-12 fpe tune with the Maccari Tesla MK2 seal

TX200 Rifle - .177 caliber - with factory piston, JM Ultra XLD, Maccari Tesla MK2 main seal
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.90 grains - 810 fps - 11.51 fpe

Outdoors - 27 degrees for 1 hour
Pellet weighed at 7.86 grains - 835 fps - 12.17 fpe

5.5% increase in energy


While the dual seal design helps to reduce the variation due to temperature changes, as with any springer there is still some variation.  In a spring piston air rifle I think you will always see variation with temperature change.

On the positive side, the amount of variation was 51% less than the hand fitted JM Tesla MK2 seal 8)

This summer I can do some comparisons in the summer heat.

Steve

Great info, thanks for doing this test Steve!!!  That's quite impressive that there is such a small difference in energy for such a large temp difference.  Even with the Maccari kit, that's not as bad as what I thought it would be.

Nice job Steve!
Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on January 13, 2019, 05:20:20 PM
Have any of you tested this kit at different temperatures and elevations?  I'm just curious how much it is affected by these variables.  It will be another month before I have a chance to check these things out, so I thought I'd throw the question out there...

Thanks!

Zack, I ran a test on my 22mm dual seal conversion today.   Outdoor temperature was 27 degrees with a light breeze.  I ran about 5 shots over the chronograph straight off the rack at room temperature, which was about 70 degrees.  I then set the rifle outside on a sandbag in the fresh snow - 27 degrees for 1 hour.

(https://i.imgur.com/kWsBeAT.png)


After sitting outside for an hour, I grabbed the rifle and quickly ran 5-6 shots over the chronograph straight from the outside.

TX200 Rifle - .177 caliber - Tony Leach 22mm conversion kit (dual seal)
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.86 grains - 806 fps - 11.34 fpe

Outdoors - 27 degrees for 1 hour
JSB 7.87
Pellet weighed at 7.88 grains - 816 fps - 11.65 fpe

2.7% increase in energy

Next, I swapped power plants and ran the exact same test using my standard sub-12 fpe tune with the Maccari Tesla MK2 seal

TX200 Rifle - .177 caliber - with factory piston, JM Ultra XLD, Maccari Tesla MK2 main seal
Indoors - 70 degrees
JSB 7.87
Pellet weighed at 7.90 grains - 810 fps - 11.51 fpe

Outdoors - 27 degrees for 1 hour
Pellet weighed at 7.86 grains - 835 fps - 12.17 fpe

5.5% increase in energy


While the dual seal design helps to reduce the variation due to temperature changes, as with any springer there is still some variation.  In a spring piston air rifle I think you will always see variation with temperature change.

On the positive side, the amount of variation was 50% less than the hand fitted JM Tesla MK2 seal 8)

This summer I can do some comparisons in the summer heat.

Steve

I was surprised to find that the higher velocity was shot in the lower temp rather than the higher temp. While 10fps is such a minor variation that it could have simply been due to "atmospheric conditions" like humidity, or maybe even pellet weight variations. Anywhoo......I do think that perhaps denser cooler air being compressed affects the velocity.

Hi Ed, No doubt that the cooler, denser air has an affect ;) In fact, I stepped outside when cocking the rifle during the cold temp testing to make sure it was pulling in the cool outside air.  So many things can affect our springers over the course of a day’s shooting.  Temp, humidity, clouds, direct sunlight. 

While there are things that can help to minimize the effects, it will never eliminate them.

Steve

Title: Re: 22mm Skirtless Conversion
Post by: Nitrocrushr on January 13, 2019, 05:36:59 PM

Great info, thanks for doing this test Steve!!!  That's quite impressive that there is such a small difference in energy for such a large temp difference.  Even with the Maccari kit, that's not as bad as what I thought it would be.

Nice job Steve!

No problem Zack, It was info I wanted to know as well ;)  There are so many things that could come into play that might have an effect on the temperature/condition related variation you would see;

Seal type
Seal material
Seal fit
Lube being used
Tar on the main spring - how much tar is on the spring

I'm sure that is just scratching the surface.  Some of the folks who have far more knowledge than I do could probably elaborate even more on this subject ;)

Steve
Title: Re: 22mm Skirtless Conversion
Post by: TonyL on January 13, 2019, 06:13:43 PM

When I moved to North Carolina a decade ago I did a similar test using my .177 R9, oring sealed piston cap, and Krytox GPL205 lube. I left the R9 in my sunroom over night when the temp dropped to the 20s and shot a few CPLs over the chrony. A couple days later I left the gun indoors and chronied the gun in temps of mid 60s. I don't remember the exact velocity (I wasn't shooting sup 12fpe) but the velocity only varied 10fps between the two temps. I was surprised to find that the higher velocity was shot in the lower temp rather than the higher temp. While 10fps is such a minor variation that it could have simply been due to "atmospheric conditions" like humidity, or maybe even pellet weight variations. Anywhoo......I do think that perhaps denser cooler air being compressed affects the velocity.

Its nothing to do with the lube, its to do with the expansion and contraction of the material used for the seal and the effect on friction it has, get your seal, measure it at 68f accurately for OD, then freeze it at 25f or so and measure it again, then heat it in an oven to 110f or more and measure it again...you will then see why the velocity goes up and down.

lets talk in mm as thats what im used too.

A seal at 25.4mm on the lip will shrink when cold, effectively sizing in better, it may shrink to 25.1mm, in an AA comp tube this is perfect sizing, the power will shoot up, smaller the seal will fail and the set up will go slammy.
The same seal when hot will grow in size, friction will increase, efficiency will decrease and power will go down, this was seen by all competitors in Poland for the FT worlds this last year, it was well over 30C so guns were running 40C+ so well over 110f
At 68f or 20C the seal is within the normal working temperature and power will be what you have set when you built the gun, no one sets the gun up seriously cold or seriously hot ;)

i run a front seal on the 22mm set up with a lip around 22.1mm or just under, when cold it will fail, BUT the O ring takes over and the shot feel remains soft as the poly seal cushions the piston, when hot the lip diameter will grow to around 22.25mm and the seal will do all the work. The O ring runs zero crush, the groove is 18mm OD it sits in and the O ring is 2mm cross section so 22mm OD,it takes pressure to blow the O ring out to form a seal.

We will never cure temperature shift, its akin so chasing your tail....you will only reduce the effects.

Title: Re: 22mm Skirtless Conversion
Post by: Gear_Junkie on January 13, 2019, 06:32:02 PM

When I moved to North Carolina a decade ago I did a similar test using my .177 R9, oring sealed piston cap, and Krytox GPL205 lube. I left the R9 in my sunroom over night when the temp dropped to the 20s and shot a few CPLs over the chrony. A couple days later I left the gun indoors and chronied the gun in temps of mid 60s. I don't remember the exact velocity (I wasn't shooting sup 12fpe) but the velocity only varied 10fps between the two temps. I was surprised to find that the higher velocity was shot in the lower temp rather than the higher temp. While 10fps is such a minor variation that it could have simply been due to "atmospheric conditions" like humidity, or maybe even pellet weight variations. Anywhoo......I do think that perhaps denser cooler air being compressed affects the velocity.

Its nothing to do with the lube, its to do with the expansion and contraction of the material used for the seal and the effect on friction it has, get your seal, measure it at 68f accurately for OD, then freeze it at 25f or so and measure it again, then heat it in an oven to 110f or more and measure it again...you will then see why the velocity goes up and down.

lets talk in mm as thats what im used too.

A seal at 25.4mm on the lip will shrink when cold, effectively sizing in better, it may shrink to 25.1mm, in an AA comp tube this is perfect sizing, the power will shoot up, smaller the seal will fail and the set up will go slammy.
The same seal when hot will grow in size, friction will increase, efficiency will decrease and power will go down, this was seen by all competitors in Poland for the FT worlds this last year, it was well over 30C so guns were running 40C+ so well over 110f
At 68f or 20C the seal is within the normal working temperature and power will be what you have set when you built the gun, no one sets the gun up seriously cold or seriously hot ;)

i run a front seal on the 22mm set up with a lip around 22.1mm or just under, when cold it will fail, BUT the O ring takes over and the shot feel remains soft as the poly seal cushions the piston, when hot the lip diameter will grow to around 22.25mm and the seal will do all the work. The O ring runs zero crush, the groove is 18mm OD it sits in and the O ring is 2mm cross section so 22mm OD,it takes pressure to blow the O ring out to form a seal.

We will never cure temperature shift, its akin so chasing your tail....you will only reduce the effects.

Well, you did a darn good job at minimizing the effects as much as possible - WELL DONE!!!
Title: Re: 22mm Skirtless Conversion
Post by: nced on January 13, 2019, 09:48:02 PM

When I moved to North Carolina a decade ago I did a similar test using my .177 R9, oring sealed piston cap, and Krytox GPL205 lube. I left the R9 in my sunroom over night when the temp dropped to the 20s and shot a few CPLs over the chrony. A couple days later I left the gun indoors and chronied the gun in temps of mid 60s. I don't remember the exact velocity (I wasn't shooting sup 12fpe) but the velocity only varied 10fps between the two temps. I was surprised to find that the higher velocity was shot in the lower temp rather than the higher temp. While 10fps is such a minor variation that it could have simply been due to "atmospheric conditions" like humidity, or maybe even pellet weight variations. Anywhoo......I do think that perhaps denser cooler air being compressed affects the velocity.

Its nothing to do with the lube, its to do with the expansion and contraction of the material used for the seal and the effect on friction it has, get your seal, measure it at 68f accurately for OD, then freeze it at 25f or so and measure it again, then heat it in an oven to 110f or more and measure it again...you will then see why the velocity goes up and down.

lets talk in mm as thats what im used too.

A seal at 25.4mm on the lip will shrink when cold, effectively sizing in better, it may shrink to 25.1mm, in an AA comp tube this is perfect sizing, the power will shoot up, smaller the seal will fail and the set up will go slammy.
The same seal when hot will grow in size, friction will increase, efficiency will decrease and power will go down, this was seen by all competitors in Poland for the FT worlds this last year, it was well over 30C so guns were running 40C+ so well over 110f
At 68f or 20C the seal is within the normal working temperature and power will be what you have set when you built the gun, no one sets the gun up seriously cold or seriously hot ;)

i run a front seal on the 22mm set up with a lip around 22.1mm or just under, when cold it will fail, BUT the O ring takes over and the shot feel remains soft as the poly seal cushions the piston, when hot the lip diameter will grow to around 22.25mm and the seal will do all the work. The O ring runs zero crush, the groove is 18mm OD it sits in and the O ring is 2mm cross section so 22mm OD,it takes pressure to blow the O ring out to form a seal.

We will never cure temperature shift, its akin so chasing your tail....you will only reduce the effects.


"nothing to do with the lube, its to do with the expansion and contraction of the material used for the seal and the effect on friction it has, get your seal, measure it at 68f accurately for OD, then freeze it at 25f or so and measure it again, then heat it in an oven to 110f or more and measure it again...you will then see why the velocity goes up and down."

Hummmm.......My experience with "tar", molly paste & factory HW piston seals a couple decades ago suggest otherwise! After I stopped using "tar" on my R9 spring (replacing it with molly paste) and replacing the old design HW factory seal a home made oring sealed piston cap my "temperature related poi shifting" was greatly reduced! I personally believe that changes in lube viscosity and piston seal durometer was due to a 30+ degree temperature differential which affected the functioning of the piston, especially since my changes in lube and piston sealing worked well. Back then (a couple decades ago) I was content simply to solve my "poi shifting issues" and never chronied the R9 while cold and warm to see if there was any velocity changes. After moving to NC I was simply wondering if my oring sealed/Krytox lubed .177 R9 would have a marked velocity difference when shot cold or warm so I took th etime to do what I never did in WV (checked velocity wamm/cold). The velocities were so similar that if there is any "temperature induced poi shifting" it's due to atmospheric conditions the pellet is flying through....not variations in velocity.
Here is my piston seal that you're suggesting I measure..........
(https://i.imgur.com/GyTMWD7l.jpg)
A later version cut from molly filled 6/6 nylon (currently testing)...
(https://i.imgur.com/dgFfuqTl.jpg)
LOL....the oring used only has a .070nominal cross section so I don't think the diameter or amount of rubber rubbing against the receiver would be effected much by temp changes.....
(https://i.imgur.com/vsXBKgBl.jpg) 
Title: Re: 22mm Skirtless Conversion
Post by: Yogi on January 13, 2019, 11:00:42 PM
Love the idea of a double seal, one for hot weather and one for cold.  Like of like DoubleMint gum! ;D 8)

Could you achieve something similar with 2 o-rings?  Different cross sections and different grove depths, maybe even different rubber compositions. :-[

Either really stupid or real great idea? :-[ :-\ >:( :(

-Y
Title: Re: 22mm Skirtless Conversion
Post by: nced on January 14, 2019, 11:30:47 AM
Love the idea of a double seal, one for hot weather and one for cold.  Like of like DoubleMint gum! ;D 8)

Could you achieve something similar with 2 o-rings?  Different cross sections and different grove depths, maybe even different rubber compositions. :-[

Either really stupid or real great idea? :-[ :-\ >:( :(

-Y

"Love the idea of a double seal, one for hot weather and one for cold"
The pic is showing a "Quad seal" cross section oring as opposed to a round cross section design......
(https://i.imgur.com/zGMYKFel.png)
Funny that you should mention "hot & cold" because I oring sealed a couple springers for a west coast shooter. His issue was that he would get poi shifting when shooting in comfortable "morning temps" but before the "daytime temps" got to 90+ degrees the poi would shift when using factory seals. The oring sealed piston cap also reduced his "high temp" poi shifting which is why several of his springers were "oring sealed".


"Could you achieve something similar with 2 o-rings?"

As far as the quad seals vs "normal" round section orings I never saw enough difference to matter. LOL. a size 020 quad seal however does take some care to make sure the seal doesn't twist in the groove when installing. I've been using standard orings for a while and they work just fine lubed with Krytox.

There are a couple issues with a double oring setup on a HW95 piston. 1st, the oring groove would need to be so wide that the piston cap would need to be made a lot thicker to keep the oring groove from cutting into the c-bore that gets pressed over the piston seal retaining "button" and the thicker cap would reduce the "swept volume" of the compression area. 2nd, double orings would also double the amount of "rubber" compressed against the receiver wall. This would increase "piston drag" and the amount of lube as the durometer of the "rubber" and the viscosity of the lube changes with the temperature defeating the reason I went with an oring sealed piston cap in the first place.

"different grove depths"
I already use modified oring groove dimensions since the HW95 receiver isn't anything close to a pneumatic clyinder that would be actuated with "mist lubricated air" and expected to work for 100s of thousands of cycles at a few thousand psi. LOL, if a factory spring in a modern springer lasts just 10,000 shots it's exceptional (Beeman R10 springs would break with less than 5,000 shots) and the compression is perhaps 1,500-2000 psi (unless the gun diesels with petroleum lubes). For my size 020 oring grooves the width is about .080 (standard dynamic groove width is .093 to .098) and I use only 10% compression (standard oring compression is 15% to 25%).

"maybe even different rubber compositions"   
I currently use 75 durometer spec Viton orings because they have relatively high heat tolerance of 400 degrees F. (nitrile about 250 degrees F). While polyurethane is a very tough wear resistant rubber, it also has a low heat tolerance of about 180 degrees F......
(https://i.imgur.com/mO4Vq2th.png)

Anywhoo......I've tried several different oring compounds, durometer ratings and cross sections and quite frankly, all will work as long as they last. :o Decades ago I tried to use the really tough polyurethane orings and they didn't hold up to the "heat of compression" very long! There are other compounds that would seem to be perfect for use in an oring sealed piston cap like Kalrez, however $20-$40 EACH for an 020 size is too pricey!! LOL.....I can buy a 25 count bag of military spec size 020 75duro Viton orings for under $10. The 4 cent each Viton orings I use will last longer than a good aftermarket spring so there is no need to use the "more expensive than gold" stuff. LOL.....I generally break down my springers yearly during the winter months for a "dustin' & cleanin" so I roll in a new 4 cent oring at that time if needed or not.