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PostPosted: Sun Sep 24, 2017 5:36 pm 
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Location: Okanagan,BC
Got this NP Pistol used; worked perfectly for the 1st 50 or so shots - at a consistent 490ish FPS with CPHPs (7.9gn)...then all of a sudden the POI changed and I chronyed it again and it had dropped to a consistent 420ish FPS... :?

It has now been at around 420 fps for awhile now - anyone have any idea what it going on?


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PostPosted: Sun Sep 24, 2017 7:15 pm 
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Location: Thunder Bay,On.
My gas ram was fine for a year and one day I lost 150 fps with the Nitro Venom.Turned out the gas ram seal had failed....at least partially.....I shot the gun for a year afterwards and it STILL shot 150 fps under normal....no more and no less...so I kept it. Could be your ram is failing too.....

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PostPosted: Sun Sep 24, 2017 7:17 pm 
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MyCrosman wrote:
My gas ram was fine for a year and one day I lost 150 fps with the Nitro Venom.Turned out the gas ram seal had failed....at least partially.....I shot the gun for a year afterwards and it STILL shot 150 fps under normal....no more and no less...so I kept it. Could be your ram is failing too.....


Any way to install a new seal?

:?


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PostPosted: Sun Sep 24, 2017 7:41 pm 
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Well......you don't know for sure if it IS the seal on the ram...but it sure sounds like it...I'm pretty sure those gas rams are not repairable...some types of air rifle rams you can fix...but not those...you may be stuck with 420 fps.....unless you want to attempt a tear down…..but its a bit of a bugger....

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PostPosted: Sun Sep 24, 2017 7:45 pm 
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MyCrosman wrote:
Well......you don't know for sure if it IS the seal on the ram...but it sure sounds like it...I'm pretty sure those gas rams are not repairable...some types of air rifle rams you can fix...but not those...you may be stuck with 420 fps.....unless you want to attempt a tear down…..but its a bit of a bugger....


OK - I guess there are worst things than a consistent 420 fps air pistol... :wink:


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PostPosted: Sun Sep 24, 2017 8:30 pm 
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Location: Edmonton
Was it dieseling at all during the first 50 shots? I bow to those above who have experienced it, but suddenly dropping down to a stable 70 fps lower bears no logic, unless I am missing something.


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PostPosted: Sun Sep 24, 2017 8:33 pm 
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Edmonton<500 wrote:
Was it dieseling at all during the first 50 shots? I bow to those above who have experienced it, but suddenly dropping down to a stable 70 fps lower bears no logic, unless I am missing something.


No - I was not aware of any dieseling - and again this was a used pistol that I bought.

And actually - it was again shooting a 490 fps again tonight - so now I am totally confused... :? :?


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PostPosted: Sun Sep 24, 2017 10:07 pm 
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Location: P.G. B.C.
Had a thought - was dieseling at one time, picked up some carbon fouling that got between the seal and the bore which reduced the speed. Over a number of shots, spit out that bit of carbon from between the seal and sleeve - now it's back to a good seal now and full power?

Like I said, speculation on possibilities. It is likely to do this again if I am right.

I would look up how to tear it down for a needed cleaning.

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PostPosted: Sun Sep 24, 2017 10:12 pm 
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I usually end up destroying these air guns if I attempt too much - but I guess I can try:

https://www.youtube.com/watch?v=2lqced2a5c0

Any chance I can just spray something somewhere to help to clean it up without doing a total teardown?


:?:


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PostPosted: Mon Sep 25, 2017 3:41 am 
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Location: Eastern Townships
I wouldn't chance it Doug. A cleaner's solvent may be harmful to the seal (if you're thinking about something that would dissolve the possible carbon build-up). I'm afraid a teardown is your better option. JMHO


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PostPosted: Mon Sep 25, 2017 2:09 pm 
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That was a difficult video to understand - perhaps I would need to watch it several times, with that gun in my hands.

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PostPosted: Mon Sep 25, 2017 2:49 pm 
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Daryl wrote:
That was a difficult video to understand - perhaps I would need to watch it several times, with that gun in my hands.


Happy to send it your way...


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PostPosted: Tue Sep 26, 2017 2:48 pm 
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Location: Northern Ontario
They are pretty straight forward to tear down. Some people claim reversing the direction of the strut increases fps, I did not find any difference.

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