Gamo Piston seal question

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Rawroots

Rawroots

Member
Nov 13, 2017
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West Olive, Michigan, United States
My gamo break barrel is only shooting 450 fps, so i took apart my first break barrel, thinking I'd find a scored up piston seal but it is smooth but seems very hard plastic, normal ? I don't know . Years ago we softened r/c car part by boiling them in water, has anybody had success doing this. Looked online for replacements and average cost is over 20 $ w/shipping, is there also a way of knowing spring is weak.
20231214_155215.jpg
 
Spring and seal +/-$20 -- you got it apart -- just go with that new stuff and see ..

You never pictured the seal or said what model gamo .. so ?

I guess that spring not broke and pretty straight hard to say that's the issue .

The seal on the piston of you gravity drop it in the tube it should not free fall on its own weight without a slight push with your finger . Slight... Also plug the transfer port hole with your finger and try to push the piston down . It should get hard and hold back pressure try to hold the best you can and if it drops any it maybe leaking past the seal.

Thing is not a real answer. From here I can only guesstamate .. Your parts are cheap so go with that and maybe have confidence in fresh new and be back in business..


P.s....

Before ording parts clean up old lube and all then use fresh lube in the proper plac s as you would going back new and test. May get lucky and and that maybe all it needs as well like poor factory lubing and seal just running dry ..

You just never know .. if it still real weak then grab the spring and seal ...
 
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Hateful McNasty said:
Spring and seal +/-$20 -- you got it apart -- just go with that new stuff and see ..

You never pictured the seal or said what model gamo .. so ?

I guess that spring not broke and pretty straight hard to say that's the issue .

The seal on the piston of you gravity drop it in the tube it should not free fall on its own weight without a slight push with your finger . Slight... Also plug the transfer port hole with your finger and try to push the piston down . It should get hard and hold back pressure try to hold the best you can and if it drops any it maybe leaking past the seal.

Thing is not a real answer. From here I can only guesstamate .. Your parts are cheap so go with that and maybe have confidence in fresh new and be back in business..


P.s....

Before ording parts clean up old lube and all then use fresh lube in the proper plac s as you would going back new and test. May get lucky and and that maybe all it needs as well like poor factory lubing and seal just running dry ..

You just never know .. if it still real weak then grab the spring and seal ...
Click to expand...
All good advice. Thank you
 
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Compressorguy said:
Dont forget to check the breach (o-ring?) seal where you load the pellet. It can also cause considerable velocity loss. You can lay a piece of toilet paper over the breach area and fire it. The paper should not move if the o-ring seal is good and doing its job.
Click to expand...

Good point , gamos ain't like best quality , but you can get some milage from them. .. sometimes you can shim under them to raise it up a tiny bit to check sealing .. gamos kinda proud of the ones mine uses ( receiver side ).
Still l only replaced on in it over 5 years just because .... Lol
 
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rule number one if you take it apart replace the guts, why, that is easy, you went to all the trouble to take it apart and clean give it new parts
is it always cost effective to do that well maybe not but you have a spring compressor, so you know that is part of the hobby
never open up a gun without replacing the breech seal first, it is easy for the most part and could save you time and money

when posting a thread give us some info make you did but model maybe it is a low power rifle and if we as readers know what your have we can look for parts to help you in your rebuild
 
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Small update ,i ordered new seal on amazon and may take 1-3 weeks, knowing I'm impatient i boiled old piston seal to soften it and it also expanded in size. Cleaned and reassembled, after 10 shots the gun settled in at 470 fps. Tried the toilet paper across breech and didn't show leakage, i even double checked chronograph with another rifle, it works fine, i checked the feed hole to barrel and it's the same size as my 22cal and 177cal, that doesn't seem right, this is a 25 cal and guessing it should be shooting closer to 700 fps not giving up
20231214_214830.jpg
 
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Mycapt65 said:
The spring in the picture has a bend it and the coils are somewhat collapsed where the bend is. Meaning the spacing between the last ten or so coils is tighter than the other end. The combination of those two things usually indicates the springs gone soft and needs replacing.
Click to expand...
Thank you, stll learning
 
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Hateful McNasty said:
One guy here review look like in your boat at 450+/- another guy using heavy 27g just under 600

https://www.pyramydair.com/product/gamo-big-cat-air-rifle-combo-synthetic-stock?m=3528

Now maybe I'm wrong but boiling the seal would cause it to expand some , bit once it cools back to ambient temperature ot shrinks back to size .. in my thinking anyway.


Don't know if this could do something

NEW-Gamo Etc. Express Package Deal- Seals, Lubes, Spring

<p />
www.airrifleheadquarters.com
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The boiling the OP is talking about was a thing we did with nylon R/C car parts, mostly suspension arms, back in the early days of the hobby. Boiling the nylon parts permanently "annealed" them making them more pliable and less likely to break upon a hard impact. Worked well with the materials of the time.

I'm thinking he wants to soften the piston seal for a better seal rather than physically expanding it. As you mentioned, when it cools it will shrink back to the original size. Without knowing the type of plastic, there's no way to know if boiling would work other than trying it.

Some of the old timers I fly R/C planes with still boil their nylon propellors to make them more chip resistant and less likely to develop a crack and throw a blade. It's not supposed to be necessary anymore, but old habits die hard.
 
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Compressorguy said:
Dont forget to check the breach (o-ring?) seal where you load the pellet. It can also cause considerable velocity loss. You can lay a piece of toilet paper over the breach area and fire it. The paper should not move if the o-ring seal is good and doing its job.
Click to expand...
Or...sprinkle a little powder over the joint, that will really show the smallest leak, easy to cleanoff after testing..
 
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Ain't much on that .25 big cat to gleen over.

A thread here maybe worth looking over for fun

$ 99 - .25 gamo big cat - clearance

....... https://northwoodsoutlet.com/product/gamo-big-cat-25-caliber-air-rifle-w-4x32-scope/ ....... ............. the (big) cat is now out of the bag ....... these are very accurate. i suspect bsa barrels...
www.airgunnation.com www.airgunnation.com
 
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Hateful McNasty said:
Ain't much on that .25 big cat to gleen over.

A thread here maybe worth looking over for fun

$ 99 - .25 gamo big cat - clearance

....... https://northwoodsoutlet.com/product/gamo-big-cat-25-caliber-air-rifle-w-4x32-scope/ ....... ............. the (big) cat is now out of the bag ....... these are very accurate. i suspect bsa barrels...
www.airgunnation.com www.airgunnation.com
Click to expand...
McNasty thank you for this thread, now i don't think there is anything wrong with this piece of s### except the deception printed on it say 800 fps with alloy pellets, shame on gamo. 12 ftlb 25cal what is this world coming to ?
 
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Rawroots said:
McNasty thank you for this thread, now i don't think there is anything wrong with this piece of s### except the deception printed on it say 800 fps with alloy pellets, shame on gamo. 12 ftlb 25cal what is this world coming to ?
Click to expand...
Well it's gamo ...lol

Matter of fact I just came in from shooting my old gamo whisper fusion mach 1 .22 .

I ain't shot it in a few months + so I got her put late today and knocked the cob webs off and out . Poor ol' girl still does ok . Needs a new piston seal bit o guess the only place to get one is Australia. ( 33mm tube ).

Some reason no body in the USA can have one to sell . Never have , never will I guess .. gamo mist sue anybody in the USA that tries to .. just funny only cas Australia can directly from them not ever listed in there Amazon or eBay usa stores ether.... Amazing..

Anyway she still truggs along on a tore seal but hits well enough ..
 
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