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 Post subject: Crosman piston seal wear
PostPosted: Tue Jan 02, 2018 9:51 pm 
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Joined: Sat Sep 03, 2005 9:25 am
Posts: 3432
Location: Ontario, Canada
Has anyone seen this sort of wear on a piston seal from a Crosman NP (Fury NP)? The seal was new and has only seen about 600 shots. Velocity dropped from 900s down to 800fps and then 600fps with CPHPs.

I pulled the rifle apart and the piston slid out into my hand when I tilted the tube. The seal was polished/ground on one side. The ground area was 180* of the perimeter and only on one side. The seal lip was ground straight on the bad side while the other side stayed fine (see picture). Have you ever seen this before? I’m guessing that maybe the chamber is rough? Soft seal? Any other ideas?


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PostPosted: Wed Jan 03, 2018 9:12 am 
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Joined: Sun Aug 19, 2007 11:44 am
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Location: Interior BC
Seal looks dry. Or did you just wipe it off? Wondering if it has anything to do with the scuff marks you see on the piston.
Can you see the same marks on the inside of the cylinder?


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PostPosted: Wed Jan 03, 2018 9:45 am 
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Location: Ontario, Canada
HuskyDude wrote:
Seal looks dry. Or did you just wipe it off? Wondering if it has anything to do with the scuff marks you see on the piston.
Can you see the same marks on the inside of the cylinder?


The piston was lubed with moly paste but everything was cleaned off for the picture details.
The scuff marks on the piston are from the manufacturer. Those areas have no contact with the receiver tube so they stay as dark scuffs. The contact area is on the top of the skirt where it gets lightly polished from contact and becomes shiny.


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PostPosted: Wed Jan 03, 2018 7:18 pm 
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Joined: Sun Jan 29, 2012 7:31 pm
Posts: 696
Location: Halifax, NS
Hacked up piston seals are common with Crosman. Check for galling inside the receiver tube, buttoning the piston will be a good solution.
Replacement Crosman seals are inexpensive from Gravel or you can pay a little more for the Red seals - can't remember what gun (German IIRC) they are for but they do fit some Crosman guns.
Before inserting piston with new seal, make a sleeve out of a cut - open pop can & insert this sleeve past the threading at the tube end; then slide seal/piston in the receiver tube.

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