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 Post subject: Grizzly Predator Seal
PostPosted: Sun Nov 21, 2021 8:58 pm 
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Joined: Thu Oct 04, 2012 10:27 am
Posts: 1329
Location: Thunder Bay,On.
Does anyone recognize this kind of piston seal that the Grizzly Predator uses...Any other guns use this type of seal?


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PostPosted: Sun Nov 21, 2021 9:41 pm 
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Joined: Sat Sep 03, 2005 9:25 am
Posts: 3903
Location: Ontario, Canada
Same seal as Snow Peak LB-600, WF-600 and the common Chinese B3 underlever rifles. The Grizzly Predator is the LB-600.

http://calibr-spring.com/en/zapchasti-k ... komp1.html

https://www.archerairguns.com/Piston-Se ... nseals.htm

Rick knows how to make an adapter so you can use the common Crosman piston seal.

https://target-tune.in/international/pr ... nd-B3.html


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PostPosted: Sun Nov 21, 2021 10:53 pm 
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Location: Thunder Bay,On.
TCooper wrote:
Same seal as Snow Peak LB-600, WF-600 and the common Chinese B3 underlever rifles. The Grizzly Predator is the LB-600.

http://calibr-spring.com/en/zapchasti-k ... komp1.html

https://www.archerairguns.com/Piston-Se ... nseals.htm

Rick knows how to make an adapter so you can use the common Crosman piston seal.

https://target-tune.in/international/pr ... nd-B3.html

Ok thats perfect I'd rather convert to Crosman seals as I have a few of those anyway and there easy to obtain...

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PostPosted: Mon Nov 22, 2021 7:20 am 
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Joined: Mon May 26, 2014 1:08 am
Posts: 696
Location: Thunder Bay
The piston seal looks like the "trampoline" seal that comes with B3s. It's a poor seal design that wears in the centre, decreases velocity over time, then it fails altogether in the centre of the seal.
The first adapter I made, I used the same dimensions as a Crosman piston taper. No good. The seal was too small when installed and the piston just fell down the compression tube. So I used SWAG (scientific wild asss guess) and increased the top and bottom diameter of the taper by 0.050". It was a good guess. It worked perfectly. An added benefit to the adapter, is it is thinner than the OEM trampoline seal, which gives a small increase in swept volume, with the concomitant increase in velocity. Note that your gun may require some fitting due to the increased stroke length.
The threaded part is 5x0.8mm. The adapter I make is one piece made from 6061 aluminum. Unscrew the OEM seal assembly and just screw the adapter in with your fingers. A drop of loctite won't hurt. I'll make an installation tool for the Crosman seal for you too. It's self explanatory when you see it.
I installed this adapter on my 3 B3s. My B3-1 (177) OEM seal was fatiguing as mentioned above. When new, the OEM seal clocked 610-620 fps. (8.18gr) After a few thousand shots, velocity dropped to around 570 fps. After installing the Crosman seal, the velocity jumped up to 720 fps. The only thing I changed was the seal! The Crosman seal is much more consistent than the OEM seal too. Extreme spread is about 5 fps.
Rather than ship it, I'll deliver it to you when I'm in town. I'll pm you when I get it built. BTW -it's free. Please pay it forward.

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PostPosted: Mon Nov 22, 2021 8:36 am 
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Joined: Thu Oct 04, 2012 10:27 am
Posts: 1329
Location: Thunder Bay,On.
ricksplace wrote:
The piston seal looks like the "trampoline" seal that comes with B3s. It's a poor seal design that wears in the centre, decreases velocity over time, then it fails altogether in the centre of the seal.
The first adapter I made, I used the same dimensions as a Crosman piston taper. No good. The seal was too small when installed and the piston just fell down the compression tube. So I used SWAG (scientific wild asss guess) and increased the top and bottom diameter of the taper by 0.050". It was a good guess. It worked perfectly. An added benefit to the adapter, is it is thinner than the OEM trampoline seal, which gives a small increase in swept volume, with the concomitant increase in velocity. Note that your gun may require some fitting due to the increased stroke length.
The threaded part is 5x0.8mm. The adapter I make is one piece made from 6061 aluminum. Unscrew the OEM seal assembly and just screw the adapter in with your fingers. A drop of loctite won't hurt. I'll make an installation tool for the Crosman seal for you too. It's self explanatory when you see it.
I installed this adapter on my 3 B3s. My B3-1 (177) OEM seal was fatiguing as mentioned above. When new, the OEM seal clocked 610-620 fps. (8.18gr) After a few thousand shots, velocity dropped to around 570 fps. After installing the Crosman seal, the velocity jumped up to 720 fps. The only thing I changed was the seal! The Crosman seal is much more consistent than the OEM seal too. Extreme spread is about 5 fps.
Rather than ship it, I'll deliver it to you when I'm in town. I'll pm you when I get it built. BTW -it's free. Please pay it forward.

Hello...that would be great..the picture you see is the before picture...I have since cleaned and dressed the seal and polished the piston to a mirror finish...However I know this present seal is STILL lacking and I would welcome your adapter kit...Plus a little extra swept volume is a bonus. :D Thank You

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