Tuning Life Expectancy of a TX200 Piston Seal?

[Sqwirl57]

I have a TX200 with a 12ftlb PG3 Vortek kit installed. All was well and good for about 3500 shots before I noticed velocity dropping out slowly. I started at 780fps with 8.44s and I'm now down to the 720s with a significantly increased spread and SD. Breech seal passes the tissue test and the spring is not broken. The spring is set for power on the top hat AND has both spacers installed for preload. Any ideas?

Current Chrono Results

Shot count: 20
Low: 705
Hi: 733
Avg: 724
STD Dev: 5.8
Spread: 28.0

9/12/21 11:16:01 AM,721
9/12/21 11:16:17 AM,719
9/12/21 11:16:34 AM,724
9/12/21 11:16:49 AM,724
9/12/21 11:17:03 AM,717
9/12/21 11:17:25 AM,726
9/12/21 11:17:40 AM,728
9/12/21 11:17:54 AM,721
9/12/21 11:18:10 AM,724
9/12/21 11:18:38 AM,726
9/12/21 11:19:15 AM,724
9/12/21 11:19:34 AM,728
9/12/21 11:19:54 AM,705
9/12/21 11:20:07 AM,724
9/12/21 11:20:21 AM,728
9/12/21 11:20:36 AM,724
9/12/21 11:20:52 AM,733
9/12/21 11:21:05 AM,731
9/12/21 11:21:18 AM,728
9/12/21 11:21:30 AM,728

 

[thumper]

Most likely a change in lockup snugness from wear in the linkage, compressed breach seals, or whatever. I'd toss some new breech seals in it right off the bat. Both of them, not just the outer. 

If the piston seal fit well on install, and it's not dieseling terribly, they last a very long time. And will usually feel very slammy when they fail. From here, I doubt it's the piston seal. 

 

[Motorhead]

Seal has the potential to be nearly the usable life of the rifle in normal service ( if correctly fitted and proper maintenance )

Really a Q that can not be answered .... But modern Urethane pistons seal last a Very very very long time !!

 

[Sqwirl57]

Most likely a change in lockup snugness from wear in the linkage, compressed breach seals, or whatever. I'd toss some new breech seals in it right off the bat. Both of them, not just the outer. 

If the piston seal fit well on install, and it's not dieseling terribly, they last a very long time. And will usually feel very slammy when they fail. From here, I doubt it's the piston seal. 

I think you're probably right. The one breech seal that I can see right now definitely doesn't look great (still seems to pass a tissue test though?) and the lockup is very loose. If I push forward on the cocking shoe the lever rises some. I'll order some breech seals and look into shimming the shoe a bit.

Thank you!

 

[Sqwirl57]

Seal has the potential to be nearly the usable life of the rifle in normal service ( if correctly fitted and proper maintenance )

Really a Q that can not be answered .... But modern Urethane pistons seal last a Very very very long time !!

Im going to the thumpers advice and swap in some new breech seals and see if I can get the lockup a bit tighter as it seems very loose to me. Half of the gap in the next picture closes up by simply pushing the cocking shoe forward until it comes to a stop in its cutout on the comp tube

 

[Motorhead]

OP stated PISTON seal .... The BREECH seals take a beating and many fail inside a few 1000 or less shots.

 

[Sqwirl57]

OP stated PISTON seal .... The BREECH seals take a beating and many fail inside a few 1000 or less shots.

I know and you are correct. My thought process was incorrect with my original post and after thumpers comment I started looking into breech seal issues and realized how often they seem to fail with this gun. I'm at a few thousand now so this makes sense. My only concern here is that when I place a tissue over the comp tube and fire, the tissue stays pretty still. Regardless, I think I should have a few breech seals on hand for this gun ready to go.

Sorry for the confusion!

 

[Motorhead]

Ideally ... when cocking lever goes into battery, the link connecting arm to shoe has some tension on it !!!

If link goes slack and can wiggle when handle is locked up .... you have an issue !!

 

[Sqwirl57]

Ideally ... when cocking lever goes into battery, the link connecting arm to shoe has some tension on it !!!

If link goes slack and can wiggle when handle is locked up .... you have an issue !!

Oh I definitely have an issue it seems. I have definitely got some wiggle in there. I'll be going through the system to see what needs fixed tomorrow after work.

 

[Pea-shooter O.G.]

I don't have a TX200, but I did experience a degraded loss of power on a springer over the course of several months and 1500 rounds. I had installed new spring/piston seal/guides in a HW95 and lubed the internals with Krytox gpl205 as I heard all the cool kids were using it. The gun was smooth, consistent and running around 700 fps. I had noticed the accuracy really dropping off and low point of impact. Chrony revealed erratic and lower FPS around 640. Tore down and found the krytox thickened. I had cleaned really well when doing this. Well, went back to what works and lasts, moly. It may not apply in your case, but with similar symptoms, I thought it might be worth mentioning. 

 

[thumper]

Lockup issues are fairly common on the TX. The change in tension on the compression tube at lockup causes the tube to move at the shot, and this causes velocity inconsistencies and hammers the breech seal out. That's my theory from messing with them for a few years. And ultimately why I went back to HW77/97s for my uses. 

For whatever reason, I noticed it more on my guns with 12ft/lb tunes. 

Lockup issues may get worse over time from wear in the cocking link holes, or cracks/wear/deforming of the cocking shoe. Just something to keep an eye on if you change your breech seals and they don't seem to be as snug afterwards. 

ARH used to sell a machined steel (OEM was sintered metal) cocking shoe as a replacement that you had to custom fit to the gun to help fine tune the lockup. Haven't been available in a couple years at least. 

Anyway, just rambling out loud. Maybe some of it helps. Hope you get your gun fixed up on the cheap and easy. Have fun.

 

[glr59]

Replace the breech seal with an HW97 seal. That will solve the problem of the double oring seal wearing out. Secondly in my experience Vortek kits always lose power initially because the springs aren't preset. They stabilize shortly after their initial power reduction and you are good to go after that.

Jerry

 

[Sqwirl57]

Lockup issues are fairly common on the TX. The change in tension on the compression tube at lockup causes the tube to move at the shot, and this causes velocity inconsistencies and hammers the breech seal out. That's my theory from messing with them for a few years. And ultimately why I went back to HW77/97s for my uses. 

For whatever reason, I noticed it more on my guns with 12ft/lb tunes. 

Lockup issues may get worse over time from wear in the cocking link holes, or cracks/wear/deforming of the cocking shoe. Just something to keep an eye on if you change your breech seals and they don't seem to be as snug afterwards. 

ARH used to sell a machined steel (OEM was sintered metal) cocking shoe as a replacement that you had to custom fit to the gun to help fine tune the lockup. Haven't been available in a couple years at least. 

Anyway, just rambling out loud. Maybe some of it helps. Hope you get your gun fixed up on the cheap and easy. Have fun.

The more I read about the gun, the more I know you are correct. I actually do like my 97K more than the TX as far as it cocks and feels in my hand so I'll probably end up with a second one in .177 for FT. For the time being I'll just try to shim where I can to tighten the system up and hopefully it'll last. I ordered 3 sets of breech seals to get me by in the meantime.

 

[Sqwirl57]

Replace the breech seal with an HW97 seal. That will solve the problem of the double oring seal wearing out. Secondly in my experience Vortek kits always lose power initially because the springs aren't preset. They stabilize shortly after their initial power reduction and you are good to go after that.

Jerry

I have some 97K seals on my shelf and some TX ones on order. I'll try the 97k seal first. Thank you!

 

[AirShot]

In over 30 years of servicing TX200 rifles never saw a wornout cocking arm link. A small dab of moly grease at the contact points will stop any wear issues. Piston seals do last a long time if a drop or two of chamber lube is added every 500-600 shots. More than likely some worn breech seals, just simple O rings, easy to replace without taking the gun apart. To make them last longet just unlatch the cocking lever when rifle is not in use so no tention/ pressure is on that breech seal. Same for a break barrel, just break open the barrel to relieve pressure on it. My original TX200 MK1 had well over 50K shots thru it with no noticible wear anywhere other than blueing worn from cocking arm. Piston seals and spring replaced about every 8-10K shots. Breech seals every 5 K shots but left cocking arm open for longer breech seal life. Springs can be a crap shoot in how long they live, no matter how good or expensive they are one never knows for sure!! As a retired toolmaker with years of metalurgy experience what a springer puts a mainspring thru is unlike anything any other spring is designed to do. Even valve springs in an engine are not abused as much as a spring in an air rifle. Good luck and let us know what you find.......

 

[thumper]

In over 30 years of servicing TX200 rifles never saw a wornout cocking arm link. A small dab of moly grease at the contact points will stop any wear issues. Piston seals do last a long time if a drop or two of chamber lube is added every 500-600 shots. More than likely some worn breech seals, just simple O rings, easy to replace without taking the gun apart. To make them last longet just unlatch the cocking lever when rifle is not in use so no tention/ pressure is on that breech seal. Same for a break barrel, just break open the barrel to relieve pressure on it. My original TX200 MK1 had well over 50K shots thru it with no noticible wear anywhere other than blueing worn from cocking arm. Piston seals and spring replaced about every 8-10K shots. Breech seals every 5 K shots but left cocking arm open for longer breech seal life. Springs can be a crap shoot in how long they live, no matter how good or expensive they are one never knows for sure!! As a retired toolmaker with years of metalurgy experience what a springer puts a mainspring thru is unlike anything any other spring is designed to do. Even valve springs in an engine are not abused as much as a spring in an air rifle. Good luck and let us know what you find.......

Leaving the cocking lever unlatched won't keep tension off the breech seals. The force of the uncocked spring still keeps tension on the seals, as the piston pushes the compression tube forward.

I have a worn out cocking link at home, and I'd be glad to mail it to you, if I hadn't welded it onto a piece of pipe to make another tool out of. Doesn't take much elongation of the pin hole to cause a drastic change in lockup tension. 

What keeps the "chamber lube" from thinning the factory lube and causing it to run everywhere, including seeping ahead of the piston seal causing dieseling? Because that's exactly what happened on the last guns I've taken apart after someone got on the "chamber lube" regiment. 

Just something for us to ponder on. 

 

[bandg]

It might or might not make a major difference but it sure seems like there would be more pressure on the seal when latched.

 

[thumper]

It might or might not make a major difference but it sure seems like there would be more pressure on the seal when latched.

Reach your finger in the stock and push the cocking link side to side. I'll bet it has such little tension on it that you can move it with one finger.

 

[AirShot]

In over 30 years of servicing TX200 rifles never saw a wornout cocking arm link. A small dab of moly grease at the contact points will stop any wear issues. Piston seals do last a long time if a drop or two of chamber lube is added every 500-600 shots. More than likely some worn breech seals, just simple O rings, easy to replace without taking the gun apart. To make them last longet just unlatch the cocking lever when rifle is not in use so no tention/ pressure is on that breech seal. Same for a break barrel, just break open the barrel to relieve pressure on it. My original TX200 MK1 had well over 50K shots thru it with no noticible wear anywhere other than blueing worn from cocking arm. Piston seals and spring replaced about every 8-10K shots. Breech seals every 5 K shots but left cocking arm open for longer breech seal life. Springs can be a crap shoot in how long they live, no matter how good or expensive they are one never knows for sure!! As a retired toolmaker with years of metalurgy experience what a springer puts a mainspring thru is unlike anything any other spring is designed to do. Even valve springs in an engine are not abused as much as a spring in an air rifle. Good luck and let us know what you find.......

Leaving the cocking lever unlatched won't keep tension off the breech seals. The force of the uncocked spring still keeps tension on the seals, as the piston pushes the compression tube forward.

I have a worn out cocking link at home, and I'd be glad to mail it to you, if I hadn't welded it onto a piece of pipe to make another tool out of. Doesn't take much elongation of the pin hole to cause a drastic change in lockup tension. 

What keeps the "chamber lube" from thinning the factory lube and causing it to run everywhere, including seeping ahead of the piston seal causing dieseling? Because that's exactly what happened on the last guns I've taken apart after someone got on the "chamber lube" regiment. 

Just something for us to ponder on.

My guess is you found a faulty cocking link, they are supposed to be hardened steel should not wear, the pin is designed to wear and easily replaced. Most folks get carried away with chamber lube, if done properly, the two drops every 500 or more rounds and worked in properly to shoot out the excess will never keave enough left to thin the other lubes in the rifle. Factory lubes are designed to prevent rust and long term storage. It is and has been recomended by AA , Beeman, and Weirich to remove factory lube and replace with proper lubricants. If properly adjusted the cocking arm when closed adds additional pressure on the breech seal, so when the arm is broke open serious pressure is relieved, the pressure from the main spring is minimal. Unlatching the cocking arm and breaking open a break barrel slightly when rifle is stored has been recomended by AA, Beeman and most other quality air gun mfgrs for many, many years. 

 

[thumper]

In over 30 years of servicing TX200 rifles never saw a wornout cocking arm link. A small dab of moly grease at the contact points will stop any wear issues. Piston seals do last a long time if a drop or two of chamber lube is added every 500-600 shots. More than likely some worn breech seals, just simple O rings, easy to replace without taking the gun apart. To make them last longet just unlatch the cocking lever when rifle is not in use so no tention/ pressure is on that breech seal. Same for a break barrel, just break open the barrel to relieve pressure on it. My original TX200 MK1 had well over 50K shots thru it with no noticible wear anywhere other than blueing worn from cocking arm. Piston seals and spring replaced about every 8-10K shots. Breech seals every 5 K shots but left cocking arm open for longer breech seal life. Springs can be a crap shoot in how long they live, no matter how good or expensive they are one never knows for sure!! As a retired toolmaker with years of metalurgy experience what a springer puts a mainspring thru is unlike anything any other spring is designed to do. Even valve springs in an engine are not abused as much as a spring in an air rifle. Good luck and let us know what you find.......

Leaving the cocking lever unlatched won't keep tension off the breech seals. The force of the uncocked spring still keeps tension on the seals, as the piston pushes the compression tube forward.

I have a worn out cocking link at home, and I'd be glad to mail it to you, if I hadn't welded it onto a piece of pipe to make another tool out of. Doesn't take much elongation of the pin hole to cause a drastic change in lockup tension. 

What keeps the "chamber lube" from thinning the factory lube and causing it to run everywhere, including seeping ahead of the piston seal causing dieseling? Because that's exactly what happened on the last guns I've taken apart after someone got on the "chamber lube" regiment. 

Just something for us to ponder on.

My guess is you found a faulty cocking link, they are supposed to be hardened steel should not wear, the pin is designed to wear and easily replaced. Most folks get carried away with chamber lube, if done properly, the two drops every 500 or more rounds and worked in properly to shoot out the excess will never keave enough left to thin the other lubes in the rifle. Factory lubes are designed to prevent rust and long term storage. It is and has been recomended by AA , Beeman, and Weirich to remove factory lube and replace with proper lubricants. If properly adjusted the cocking arm when closed adds additional pressure on the breech seal, so when the arm is broke open serious pressure is relieved, the pressure from the main spring is minimal. Unlatching the cocking arm and breaking open a break barrel slightly when rifle is stored has been recomended by AA, Beeman and most other quality air gun mfgrs for many, many years.

First off, its "Weihrauch"

Secondly, the cocking arm is softer than the pins. A simple test of running a file across both will reveal that. 

Third, the cocking arm isn't adjustable. 

Fourth, do you honestly think that the force of the cocking arm held by a small spring loaded ball, is enough to overcome the mainspring in an uncocked gun?

Fifth, not a single well regarded spring gun tuner that I have ever heard of recommends using chamber lube. And aside from RWS at one time, I haven't seen a manufacturer that does either. Where does it "work in" too? What's in chamber lube? Any idea?