Seal damage found on my HW97k- Looks like dry fire.

[Charles Outdoors]

I installed the TbT Maxi Pro kit in my HW97k yesterday and found the seal looks like it was dry fired repeatably. I received it new and have pretty much only shot JSB and Air Arms 8.4 grain pellets. May have tested some cheap pellets but don't remember. Nothing lite weight.

Looks like it was dry fired over and over. Some JSB/AA pellets fit loose. I wonder if they could cause this? Also, What seal would be the best replacement, ARH or Vortek.

[limbshaker]

Yep. Loose pellets can cause a near dry fire situation. The dieseling form the lubes burning in a new gun will also cause the seal to get brittle near the transfer port location. Sometimes factory seals don't fit quite as snug as they should, and this can exaggerate the problem. Check your breech seals too. 

Personally I prefer ARH seals. They always seem to fit consistently and are made out of a time tested material, unlike the new material Vortek uses.

But whatever you get be sure to take the time to size it correctly. That's the big thing.

[DevilsLuck]

Could the spacer be causing the seal to be getting "hammered" between the piston, and the end of the compression tube?

[Charles Outdoors]

Could the spacer be causing the seal to be getting "hammered" between the piston, and the end of the compression tube?

This was damage done before the tune kit was installed. I just didn't have a seal to replace it with hoped this one would work until I get a replacement. 

Odd thing is I don't notice flyers even with the looser fitting pellets from the tin. At least not like I would expect. 

[stija]

Looks like there is evidence of melting, at least to me.

[Grover]

I opened up my HW95 a while back after about 1000 shots, and my seal looked identical to yours.  Never dry-fired the rifle and I owned it since new.  Just as you, I had noticed no discernible performance issues.  Perhaps there is a defect in the seals?

I replaced mine with a Vortek seal I had on hand.  Tack driver.  

[Charles Outdoors]

Thanks Ron, I'm not going to worry about it. Maybe it is something with the seals. It does kinda look like hot gases ate into it near the transfer port.

Think I'll order a Vortek seal and give that a try. 

Decided to order both the Vortek and the ARH's seal and see what works best.

[nced]

I opened up my HW95 a while back after about 1000 shots, and my seal looked identical to yours.  Never dry-fired the rifle and I owned it since new.  Just as you, I had noticed no discernible performance issues.  Perhaps there is a defect in the seals?

I replaced mine with a Vortek seal I had on hand.  Tack driver.  

Hummm....here is the factory piston seal from the HW95 I bought last year before replacing it with my normal home rolled oring sealed piston cap after 1200 shots lubed with Krytox GPL205.........

I do have to mention that the gun was detuned to my usual 850-860fps level with 7.9 drain CPLs from my factory velocity of 880fps. Perhaps this is why there wasn't any "destruction" going on.

[Grover]

I opened up my HW95 a while back after about 1000 shots, and my seal looked identical to yours.  Never dry-fired the rifle and I owned it since new.  Just as you, I had noticed no discernible performance issues.  Perhaps there is a defect in the seals?

I replaced mine with a Vortek seal I had on hand.  Tack driver.  

Hummm....here is the factory piston seal from the HW95 I bought last year before replacing it with my normal home rolled oring sealed piston cap after 1200 shots lubed with Krytox GPL205.........

I do have to mention that the gun was detuned to my usual 850-860fps level with 7.9 drain CPLs from my factory velocity of 880fps. Perhaps this is why there wasn't any "destruction" going on.

Ed, perhaps they're a tad overpowered?  How much did you take off?  1/2coil?

[nced]

I opened up my HW95 a while back after about 1000 shots, and my seal looked identical to yours.  Never dry-fired the rifle and I owned it since new.  Just as you, I had noticed no discernible performance issues.  Perhaps there is a defect in the seals?

I replaced mine with a Vortek seal I had on hand.  Tack driver.  

Hummm....here is the factory piston seal from the HW95 I bought last year before replacing it with my normal home rolled oring sealed piston cap after 1200 shots lubed with Krytox GPL205.........

I do have to mention that the gun was detuned to my usual 850-860fps level with 7.9 drain CPLs from my factory velocity of 880fps. Perhaps this is why there wasn't any "destruction" going on.

Ed, perhaps they're a tad overpowered?  How much did you take off?  1/2coil?

No, whenever I buy a new HW springer I immediately replace the factory spring with a ARH offering that's fitted with a home rolled guide and top hat. To keep the CPL velocity within the 850-860fps range I use a .120 wire spring with about 34 coils........
What I'm currently using in my R9 & HW95..........

This is the spring kit that's currently in my HW95 however I did reduce the top hat flange thickness a bit to get the velocity down to 865fps.........


I suppose that removing a coil from the factory HW spring would reduce the velocity but I've found that cutting off coils, heating and closing the end, plus grinding the end flush is more work than I'm willing to put into a factory HW spring considering the "life span" of most of the factory HW springs I used was less than two cases of CPLs (10,000 shots = about a year of shooting).

As a side note...when I used old design "thin parachute edge" factory HW piston seals in my R9 I would get seal erosion at the transfer port like this.......

At that time (decades ago) I was tuning my .177 R9 to shoot CPLs at 920fps and the seal face would get eroded at the transfer port but I never had one where the face of the seal was cracked. Perhaps the new design HW95 piston seals are made from a different compound than the old seals. Here is a bit of HW piston seal history over the years with my .177 R9s........


By the way, CPLs at 920fps even eroded the face of some after market piston seals I used years ago............


Piston seal erosion was one of the issues that started my oring sealed piston cap experimenting decades ago to eliminate piston seal erosion.......
First experimental oring sealed piston cap after 4000 shots.........


The oring sealed piston caps have evolved a bit since the early days and my latest twist was to clad the piston cap sides with a Delrin bearing like this........


Anywhoo....one of the issues I've had with the new design factory HW95 piston seals was that the diameters aren't very consistent and I've tested some seals that fir the receiver nicely and others that fit what I consider too loose. I never used a new design factory seal long enough to test durability but I suspect that if I were shooting a "loose fitting seal" for any length of time there may be some impact damage like what was posted............I really don't know.