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Pneumatic dismantling: how to get inside

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popgun pete

popgun pete

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Jul 30, 2008
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The real pressure seal on the piston is the rear "O" ring, although the cup seal behind it can also hold pressure as I had a gun with the "O" ring damaged and the gun still held air. The front "O" ring on the piston is more of a guide and it is that which you can feel hitting the uneven surface where the rust has stuck which transferred from the piston's corroded rear metal section. Some pistons don't have two "O" rings, they just have the rear one along with the cup seal. If in doubt replace the piston as once you get rust on an item it is more susceptible to rusting there again due to the rough surface where rust once was. Also guns need to be thoroughly rinsed after use, especially vacuum barrel models due to the water trapping mentioned before and that includes pushing the piston back with the then exposed surface being flooded with freshwater and then being let out. A gadget can be made to replace the spear in pushing the spear back a short distance, something like this one from Nemrod, however it needs to be of the shaft diameter or slightly less where it penetrates the muzzle.
Nemrod plunger R
 
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popgun pete

popgun pete

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I am actually surprised that after all this time manufacturers of vacuum barrel guns or kits don’t offer such a piston pusher as a standard accessory. The advantage besides being short is they don’t jam in the piston nose when you push the piston back, so are easy to pull out of the gun when you finish pushing.

These pushers could be made of Delrin or one of the harder plastics similar to that used in piston bodies and shock absorber anvils.
 
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popgun pete

popgun pete

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A diagram showing how saltwater traps. Note even vacuum barrel guns have water enter the inner barrel as it was in the muzzle entrance when you loaded the gun underwater with the insertion of the spear tail.
MUZZLE WATER ENTRAPMENT R
 
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Stamatis

Stamatis

Active Member
Aug 29, 2017
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A diagram showing how saltwater traps. Note even vacuum barrel guns have water enter the inner barrel as it was in the muzzle entrance when you loaded the gun underwater with the insertion of the spear tail.
View attachment 58055
Thank you so much for all your invaluable info, much appreciated! I will order a piston ASAP!

Update: This is annoying. Still, no merchant in Greece imports Salvi spare parts. grrrr!
 
Last edited:
Stamatis

Stamatis

Active Member
Aug 29, 2017
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I decided to change the oil again because it seemed to me that it is very dark after using the gun for only a couple of shots. I used Salvi's green oil.
I also added some grease directly to the piston. After adding some pressure, I don't feel the bump anymore. I think this confirms that corrosion is causing the issue. I think I'll get the salvimar race kit since it looks like I am ordering from Italy again.

20220706 204249
 
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