Air Venturi Odd size o-ring question

Hi all,
Sorry in advance if this is too long a read, but I'm hoping for some advice...

I've been trying to fix a slow air leak in my Avenge-x .22 and not having much luck so far. I've replaced o-rings on the axle (they were brittle and flattened out) and replaced the dowty seal behind the fill pressure gage (and gently tightened that down). Although not as bad, there is still air escaping somewhere that I can't seem to locate with soapy water or silcone. Even though they look okay, I'll probably try replacing fill probe and air cylinder o-rings next before venturing deep into the receiver to replace 0-rings. For those interested, there are a couple of videos on YouTube by Shooter's den in Pakistan that give a very detailed and closeup view of how to completely tear down the Avenge-X. They're very helpful, especially if you use english translation closed captions!

Anyway, as I've been doing this, it occurred to me that I should probably build up a supply of spare o-rings for future repairs. I could buy a complete reseal kit for around $30-$40, or I could put together an order from a place like O-rings and More and get a lifetime supply at a fraction of the cost. I've ordered from them in the past. It's hard to beat a pack of 25 o-rings for pennies plus nominal shipping. I can also wait for Captain O-ring to start selling an Avenge-X reseal kit - an attractive option because Jon puts together a color coded sheet to go along with the color coded o-rings, making it so much easier to identify o-rings. But Jon tells me that kit is weeks away and I'm sure it'll also be in the $30+ range.

My question has to do with odd or non-standard 0-ring sizes and what to use if I can't get them. For example, nearly all the 0-rings needed for the Avenge-X are standard metric sizes (20 i.d. x 2 c.s., 4 x 1.5, 2.5 x 1.5, etc.) However, there are a few that aren't so standard. I'm referring to both the shematic drawing of the rifle from Pyramyd Air along with a parts list (partially in Chinese) that I found from Nova Vista. On that list, there are 0-rings such as 12.4 x 2.6, 2.4 x 1.8, 20.2 x 3.5, and one that's simply denoted as 10 (#69 on the schematic - any ideas what that is?). I can't find any 0-rings with these dimensions and I'm wondering if I can use the nearest standard size instead. So, for example, instead of 12.4 mm, use 12.5 mm; instead of 20.2 mm, use 20 mm; instead of 1.8 mm, use 2mm. What do you think?

Also, a few of the 0-rings listed do not specify the hardness (Buna 70 or 90). In cases like that, which do you go with?

Thank you for any help you can offer with this!
Mike
 
Thanks!
I agree, and I actually did speak with Ted a few days ago for quite some time about the leak issue. He’s the one who told me to start with the axle o-rings. I’ll probably be calling him again soon. 😉
I put a list together a long while back on the avenger platform and found a good majority of the sizes needed were JIS o rings
Very helpful, thank you!
 
Mike
FWIW
Many metric O-Rings are actually equivalent to AS568 Standard American O-Rings
For example, the barrel O-Ring for may Ranchero is specified to be 5.28mm ID X 1.78mm CS, DURO 70 and is actually the same as a #009 O-ring
If you are shopping at the O-Ring Store this is easy to find out
Take a look at their attached #009 O-ring page

Hope this helps

Just my 2 rings
Edward

Screenshot 2025-01-07 090141.png
 
  • Like
Reactions: MikeyJ
Regarding durometer, a harder elastomer better resists the extrusion forces of higher pressure. Generally speaking, 70 durometer is good for most PCP duties except in places where the sustained pressure is over 250 bar (3600psi). It really just depends on part tolerances—the size of the gaps the O-rings must seal—but this guideline seems to work well across most brands and price brackets.

So for the Axenge-X, the reservoir and the high pressure side of the regulator are probably the only places where 90 durometer is needed.

With that said, you can often use them elsewhere. Just be aware there is an elevated risk of being damaged during installation since they don’t compress as readily. Deburring and silicone lubrication make a big difference.
 
  • Like
Reactions: MikeyJ
Hi all,
Sorry in advance if this is too long a read, but I'm hoping for some advice...

I've been trying to fix a slow air leak in my Avenge-x .22 and not having much luck so far. I've replaced o-rings on the axle (they were brittle and flattened out) and replaced the dowty seal behind the fill pressure gage (and gently tightened that down). Although not as bad, there is still air escaping somewhere that I can't seem to locate with soapy water or silcone. Even though they look okay, I'll probably try replacing fill probe and air cylinder o-rings next before venturing deep into the receiver to replace 0-rings. For those interested, there are a couple of videos on YouTube by Shooter's den in Pakistan that give a very detailed and closeup view of how to completely tear down the Avenge-X. They're very helpful, especially if you use english translation closed captions!

Anyway, as I've been doing this, it occurred to me that I should probably build up a supply of spare o-rings for future repairs. I could buy a complete reseal kit for around $30-$40, or I could put together an order from a place like O-rings and More and get a lifetime supply at a fraction of the cost. I've ordered from them in the past. It's hard to beat a pack of 25 o-rings for pennies plus nominal shipping. I can also wait for Captain O-ring to start selling an Avenge-X reseal kit - an attractive option because Jon puts together a color coded sheet to go along with the color coded o-rings, making it so much easier to identify o-rings. But Jon tells me that kit is weeks away and I'm sure it'll also be in the $30+ range.

My question has to do with odd or non-standard 0-ring sizes and what to use if I can't get them. For example, nearly all the 0-rings needed for the Avenge-X are standard metric sizes (20 i.d. x 2 c.s., 4 x 1.5, 2.5 x 1.5, etc.) However, there are a few that aren't so standard. I'm referring to both the shematic drawing of the rifle from Pyramyd Air along with a parts list (partially in Chinese) that I found from Nova Vista. On that list, there are 0-rings such as 12.4 x 2.6, 2.4 x 1.8, 20.2 x 3.5, and one that's simply denoted as 10 (#69 on the schematic - any ideas what that is?). I can't find any 0-rings with these dimensions and I'm wondering if I can use the nearest standard size instead. So, for example, instead of 12.4 mm, use 12.5 mm; instead of 20.2 mm, use 20 mm; instead of 1.8 mm, use 2mm. What do you think?

Also, a few of the 0-rings listed do not specify the hardness (Buna 70 or 90). In cases like that, which do you go with?

Thank you for any help you can offer with this!
Mike
Go to AliExpress and buy the various o'ring collections. 1.9, 1.5, 2.0, 3.1. You will end up with what you need 95% (or more) of the time. O'ring sets specific to a gun are way over priced and useful usually only for that gun. I also bought both rubber and silicon o'rings because you just can't have too many o'rings when dealing with air guns.

-- Matt
 
  • Like
Reactions: Firewalker