Recommended Piston Seal for a HW 50.

[Yogi]

I have an Aussie Seal, a Vortek Moly seal, and an OEM seal.
FWIW-In another HW 50 the Aussie seal worked great for 100-200 pellets.  Then velocity dropped.  Upon disassembly a nick in the side of the seal was noted. I have a spare.
In the same gun, the Vortek seal, even after 100-200 pellets, had a very inconsistent POI. I have a spare.
The OEM seal is lightly used.

The best that I can measure, my compression chamber's ID is 1.0055".

Any suggestions?

-Yogi

[two4spooky]

I have or have used: Vortek, Custom Air Seals(Aussie)both color/materials, ARH and of course factory. I like the Vortek best by a good margin. A little slow to settle/fit but very good and durable. The maroon/purple colored Aussie seal is good but not Vortek good IMO. Love ARH springs and kits, seals not so much. The factory Weirauch seal is good if no excess oil/grease or nicks/cuts upon assembly. There always seems to be too much lube or haste at the factory building the rifle though. Rebuild with factory seal you are golden if not as durable or long lasting as Vortek. There is a brand of seal(red) being made in the UK recently that is supposed to be good, no experience with it though.  In short, go with Vortek.

[Yogi]

Thanks Stuart,

This all started because I am swiching from moly to Ultimox.  The OEM seal has some moly seemingly embedded in it.  If I could remove that moly I might try reinstalling the OEM seal.  Any suggestions on best way to do it without deteriorating the seal?
The Vortek seal seems to seal well.  When I put my finger over the transfer port and push the piston in, light resistance at first building to I can not push the piston in all the way.  My only issue with it is that when it was in, I would get 3 good shoots and then one two inches high and 2 pellets 4 inches low, then back to good shots....go figure.
Also, the Vortek seals are not to hard to put on.  They are difficult to take off!    When on, I can spin them around pretty easily.

-Y

[two4spooky]

Yes. FWIW, all I use is Krytox 205 or 215(?) when rebuilding springers, triggers and barrel pivots excepted. Still using moly lubes on barrel pivots and triggers though. I think Ultimox will fall in the same lube category with Krytox. So no difference as far as seals are concerned. I would not be concerned with a small/minuscule amount of moly on the piston seal or compression chamber. Cross contamination should be little and far down the road if rebuild is done correctly. Just my opinion/experience. No issues. **Full discloser-Much/most of what little I know I have learned here from Ed, Ron and Hector here on GTA. I have only rebuilt/redone my personal collection, ~15 or so mostly Weirauch springers. Likely/hopefully one of these mentioned experts will chime in with true expertise.**   

[two4spooky]

To clarify, I use Krytox on both Vortek seals and the Aussie seals. Both are said to be made with or impregnated with "moly". No seal issues, degradation or dieseling yet in my three or four'ish years using this combination. Longer term I do not know but possible/likely issues should have shown up by now I would think.

[Bayman]

The nick in the seal is installer error.  There's a lot of windows in the 50 that can nick a seal. I've done it myself several times. I prefer the Vortek seals over the others and I have tried all of them.

That said I will say that I'm experiencing power losses and POI issues after a couple of hundred shots when shooting extended sessions during this heat wave. This seems to be caused by the guns inability to disperse compression heat that creates greater than normal seal expansion. That has been causing extra drag which turns to power loss. If I set the guns in the shade to cool off for a half hour the power and accuracy returns.

This heat has affected all of my guns. I have tried a JM seal and the results were the same.

Also I use different lubes on different guns. I used Krytox in my HW50 since it came to me new with a lightly scored comp tube. My 50 was loosing a lot of power during sessions and when I took it apart it had a broken spring and the Krytox was sticky. I believe the Krytox was contaminated with water from internal condensation being pushed into it under compression. Now the gun would sweat profusely coming from the 72 degree AC house to 98 degree humid outside. So maybe this is avoidable. I any event I cleaned all the parts and switched it to the tan Vortek grease. Now it's shooting great for a couple hundred shots like the others.

The Weihrauchs alway seem to loose some power and accuracy when shot extensively but high ambient temperatures will exacerbate the issues.

Also make sure your gun isn't dieseling that's the most common cause for POI issue. Cut seals almost always induce extra dieseling.

[Yogi]

Tomorrow, I will break it down again, clean everything as well as possible, re-lube, install a new Vortek seal and hope for the best.

Thanks for the comments,

-Yogi

[Jason_Garvin]

The nick in the seal is installer error.  There's a lot of windows in the 50 that can nick a seal. I've done it myself several times. I prefer the Vortek seals over the others and I have tried all of them.

That said I will say that I'm experiencing power losses and POI issues after a couple of hundred shots when shooting extended sessions during this heat wave. This seems to be caused by the guns inability to disperse compression heat that creates greater than normal seal expansion. That has been causing extra drag which turns to power loss. If I set the guns in the shade to cool off for a half hour the power and accuracy returns.

This heat has affected all of my guns. I have tried a JM seal and the results were the same.

Also I use different lubes on different guns. I used Krytox in my HW50 since it came to me new with a lightly scored comp tube. My 50 was loosing a lot of power during sessions and when I took it apart it had a broken spring and the Krytox was sticky. I believe the Krytox was contaminated with water from internal condensation being pushed into it under compression. Now the gun would sweat profusely coming from the 72 degree AC house to 98 degree humid outside. So maybe this is avoidable. I any event I cleaned all the parts and switched it to the tan Vortek grease. Now it's shooting great for a couple hundred shots like the others.

The Weihrauchs alway seem to loose some power and accuracy when shot extensively but high ambient temperatures will exacerbate the issues.

Also make sure your gun isn't dieseling that's the most common cause for POI issue. Cut seals almost always induce extra dieseling.

I have a single HW 30 deluxe I leave out in my shop (pole barn not climate controlled, concrete and osb walls).  This is my grab air rifle for unwanted critters and it stays acclimated.

I have giving up years ago allowing my guns or airguns sweat like that.  I either don’t drag them out this time of year, or if I do, take them out slowly, sometimes the night before and leave them in the case.

I have never bit on the whole space shuttle lubes and don’t have issues with what I use.  I have used Vortek lubes with his kits (pre pg4), and ARH cold weather tar and moly on ARH kits.  I don’t shoot completely other than against myself, and after a couple of sighters, I am good for the day and don’t chase poi. 

I also prefer the Vortek seal, time will tell but no issues in any of my rifles.  I have only used one cup face Ausie in a 97k, I found this to work well in the comp tube.  I don’t think I would use it in a break barrel.  I have their budgets seals on hand but have never used one.

Jason

[Bayman]

The nick in the seal is installer error.  There's a lot of windows in the 50 that can nick a seal. I've done it myself several times. I prefer the Vortek seals over the others and I have tried all of them.

That said I will say that I'm experiencing power losses and POI issues after a couple of hundred shots when shooting extended sessions during this heat wave. This seems to be caused by the guns inability to disperse compression heat that creates greater than normal seal expansion. That has been causing extra drag which turns to power loss. If I set the guns in the shade to cool off for a half hour the power and accuracy returns.

This heat has affected all of my guns. I have tried a JM seal and the results were the same.

Also I use different lubes on different guns. I used Krytox in my HW50 since it came to me new with a lightly scored comp tube. My 50 was loosing a lot of power during sessions and when I took it apart it had a broken spring and the Krytox was sticky. I believe the Krytox was contaminated with water from internal condensation being pushed into it under compression. Now the gun would sweat profusely coming from the 72 degree AC house to 98 degree humid outside. So maybe this is avoidable. I any event I cleaned all the parts and switched it to the tan Vortek grease. Now it's shooting great for a couple hundred shots like the others.

The Weihrauchs alway seem to loose some power and accuracy when shot extensively but high ambient temperatures will exacerbate the issues.

Also make sure your gun isn't dieseling that's the most common cause for POI issue. Cut seals almost always induce extra dieseling.

I have a single HW 30 deluxe I leave out in my shop (pole barn not climate controlled, concrete and osb walls).  This is my grab air rifle for unwanted critters and it stays acclimated.

I have giving up years ago allowing my guns or airguns sweat like that.  I either don’t drag them out this time of year, or if I do, take them out slowly, sometimes the night before and leave them in the case.

I have never bit on the whole space shuttle lubes and don’t have issues with what I use.  I have used Vortek lubes with his kits (pre pg4), and ARH cold weather tar and moly on ARH kits.  I don’t shoot completely other than against myself, and after a couple of sighters, I am good for the day and don’t chase poi. 

I also prefer the Vortek seal, time will tell but no issues in any of my rifles.  I have only used one cup face Ausie in a 97k, I found this to work well in the comp tube.  I don’t think I would use it in a break barrel.  I have their budgets seals on hand but have never used one.

Jason

Jason your information is very valid and informative. I've always held your opinion and experience in high regard. Thank you for adding a pragmatic approach.

[Yogi]

Jason,

I decided to move away from moly grease after last summer when I was up in Oregon for a shoot.  They always schedule it for the hottest day of the year, starting in the middle of the day.!  Last year it was 107.  My HW 50 started smoking, no detonation, but lots of smoke everytime I opened the barrel to load another pellets.  I vowed then to convert to space age lubes.  On the days that my POI was wandering after new piston seals, it was only 75-80 degrees.

-Y

[Jason_Garvin]

Jason,

I decided to move away from moly grease after last summer when I was up in Oregon for a shoot.  They always schedule it for the hottest day of the year, starting in the middle of the day.!  Last year it was 107.  My HW 50 started smoking, no detonation, but lots of smoke everytime I opened the barrel to load another pellets.  I vowed then to convert to space age lubes.  On the days that my POI was wandering after new piston seals, it was only 75-80 degrees.

-Y

That is plenty warm for sure, even worse if the rifle is in the sun!!  There are several options for lubes that are proven, we all just migrate to what works best in our environments,

Jason