Why does my new to me BT SA-17 suddenly vent CO2?

[Chandlercv]

New to BT SA-17s and 12g's in general.

I've just replaced all the o-rings on a pretty abused SA-17 (abuse not by me).

It seems to not leak immediately after putting in a fresh 12g, but for 2 of the 3 12gs I've tried so far, after what seems like about 5 or 6 shots, it decides to start venting CO2 down the barrel.

Is this a thing other's have experienced? If so, has anybody identified a root cause?

[XEMON]

Most likely it's the valve seat ...

[Carp]

Dang my slow typing, you Ninja'd me! 😆

[Carp]

Full disclosure: I have no experience with the BT SA-17 marker. But, it sounds like you may need a new valve spring or cup seal

[Chandlercv]

Thanks for the insight.

I had discounted the cup seal because it didn't immediately vent, only after a few shots.

Will report back after trying with a new cup seal.

[Alexndl]

Intermitent leak are usually not caused by an oring
potentially its due to the lost of pressure behind the valve when the 12g is more empty. So either a small imperfection on the cup seal or a weak valve spring would be my first guess too

[Brokeass_baller]

I had a weak valve spring in a WSP. Caused all kinds of headaches for me, until i figured it out.

[Chandlercv]

tl;dr: Are CO2 puncture seals for tiberiuses, or from Palmers or CCI likely to be the same size as the SA-17 puncture seals? The SA-17 seal is OD: 13/32, ID: 5/32 CS:1/8 with a square profile (and seem to be urethane)

The story behind the story:

So, when I disassembled the marker, the CO2 puncture seal was absolutely shredded. That was not too, too surprising since every o-ring I replaced had basically crumbled to dust when removing them.

The players parts kit I ordered to get the new cup seal and spring had a couple of replacements for the seal, which was fortunate, because everybody is claiming they are out of stock and the part is discontinued.

After replacing the cup seal, spring, and puncture seal, everything aired up and shot well for 20 balls.

After setting the marker down for a few minutes, though, there was a pop and a hiss. After verifying there was no longer any pressure present, I removed the 12g and discovered that the puncture seal was shredded again.

If the new, old stock for the SA-17 puncture seals are all too dried out to last more than a 12g, what are my options here?

[Carp]

If the Tib 8/9, PPS Sheridan or CCI 12g face seals don't work. Hmmmm.... 🤔
I can think of 4 options...
1. Buy a punch set along with some gasket material and create your own.
2. Contact XEMON and see if he's able to 3d print some for you.
3. Hang the marker on a wall somewhere in your home and fantasize about, what could of been, some fun times.
Finally... Last resort!
4. Just throw the marker in a smelter and put you mind at ease.

[Chandlercv]

Does anybody have any of those seals and a caliper and a willingness to post up about the dimensions of said seals? Just to save me the trouble of ordering some to measure them myself.

[XEMON]

if i remember to dig out my spare bodies, ill measure one, but it wont be before next week ...
Ill probably print a few too (i need to do a few batches of sheridan seal so the printer will be loaded)

Edit: if youre OK waiting, ill send you a pair to try out.

[Chandlercv]

Xemon,

I'd be most grateful to try a pair out, especially since I've just determined that the First Strike seals won't work.

Thanks!

[Chandlercv]

Update: I acquired some punches and some gasket material (https://www.amazon.com/Neoprene-12x1.../dp/B06ZZZ5W1L).

The puncture seal I created with these worked. For about 40 minutes. Which was about what I was seeing from the ancient urethane ones I acquired in the players parts kit.

Questions:
1. Is that generally what's expected out of puncture seals, that they only provide a seal for 30-60 continuous minutes?
2. Would I have better luck with https://www.mcmaster.com/gaskets/rub...thickness~1-8/ in an 80A hardness?

[XEMON]

I don't know about #2, but my SA-17 stays aired up all day ...

I'm a bit out for the seals, but I'll send you a few to try out when I print them.
There are a few orings on the assembly, maybe another one?
the one inside is a not static, make sure it's well oiled/greased.
Here is a pic of the entire assembly:

[Chandlercv]

Further update on things that do not work:

- First-strike puncture pin seals; way too small
- TIPx puncture pin seals; annoyingly too small (that is, they're almost the right size, but not close enough to matter.
- Abrasion-Resistant Polyurethane Rubber Sheets 80A + punch kit - does not make seal; insta-vent
- Abrasion-Resistant Polyurethane Rubber Sheets 60A + punch kit - makes a decent seal. Blows out after 1 or 2 cartridges. This is the same behavior as the seals that came with the player parts kit.

If anybody has any suggestions on what else I can try, I'd be much appreciative

[XEMON]

Did you try putting a shim on the back of the 12g?
Maybe the issue is not the seal at all ...

[mueller]

Wow this thread is relevant to my interests

I too have an SA17 that wants for a new 12 gram seal. "new" old stock one blew out after just a few shots.

[mueller]

anything more happen here? Have an SA17 in box waiting for 12g seals to exist

[XEMON]

I've been busy with other projects, but this is still on the list ... I got a few things I need to do to sa-17s ..