AA Vigilante Output Port Threads?

[Toestr]

I just got one, and the port I was going to install a gauge in had a burst disk in it. The gauge won't thread into the port. The hollow set screw for the burst disk threads into the output port. Can someone confirm whether or not these are npt threads? I'm thinking not because they don't fit my thread gauge nicely, but it also kinda just looks stripped.

[FredMnkyDad10]

I had to double check mine to be sure. but there are no burst disk on the ones I have. I think you are right. Someone force a burst on there and stripped the threads. Unireg is the only one I have that has a burst disk.

[Toestr]

The screw for the burst disk looks to be 3/8-24. It's actually close enough that it starts to thread into 1/8 ports pretty deep before it gets hung up. I even had trouble telling the difference on my thread gauge.

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[The Inflicted]

Mine has a short plug that will not go in far enough to be flush with the reg.
That little plug is the only thing I have that will thread into that hole- I've got shorter plugs that I'd rather put in there, so that they could be flush, but none of them will go in correctly.

[Toestr]

Mine has a short plug that will not go in far enough to be flush with the reg.
That little plug is the only thing I have that will thread into that hole- I've got shorter plugs that I'd rather put in there, so that they could be flush, but none of them will go in correctly.

Are these 1/8 plugs or 3/8-24? I'm now fairly certain that 3/8-24 is the correct threading for that port. Tapered npt threads wouldn't work to tighten down on a burst disk.

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[The Inflicted]

Are these 1/8 plugs or 3/8-24? I'm now fairly certain that 3/8-24 is the correct threading for that port. Tapered npt threads wouldn't work to tighten down on a burst disk.

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Zombie thread but,

I ordered some 3/8-24 plugs off of eBay and they did not fit.

[Toestr]

Maybe it was 1/4"-28 considering that 1/8"-27 NPT was pretty close. I don't know. It's been a while.

[DocsMachine]

Virtually all Air America regs had two input ports, and a burst disc. I'm not sure I ever knew what the disc was rated for, probably CO2 pressures, or 1800 psi. (Keeping in mind that most of them were developed in the CO2 era.)

The two opposing ports are 1/8" NPT as usual, the burst disc port is 3/8" fine, straight. If you have a 3/8" fine- straight thread- plug that won't screw in, chances are somebody tried to jam a gauge in there and damaged the threads.

The old loose-disc burst discs are basically unobtainable these days (unless AA is making them again) so it is possible to lightly chase the threads for that port to accept a gauge. Problem there is the port is shallow, and most taps won't cut far enough to let a gauge or typical fitting seat. I have a tap I ground back years ago- almost a quarter inch- for things like that, but then it can be tricky to start in the threads. It's all too possible to damage them and render the reg unusable.

Doc.

[M98punk]

If you put a gauge in the only thing you will find out is what the output pressure of your tank is. To set a vigi you have to measure from the top.

[Shane-O]

The burst disc is after regulation, so it will read out put pressure. That burst disc is to prevent reg spike to the gun. Iirc it was a 1200psi burst disc.

[M98punk]

That’s what I get for reading quick at night while walking the dog.

Years ago someone sent me sketches of a nasty pnuemag shotgun build using a vigilante to power two separate triggers. He had to switch from a LPR mounted to the bust disc port to a Frankenstein LPR barb because there isn’t a-lot of meat there. That was when I learned about LP springs for Viggis

[FlightMedic938]

DocsMachine Toestr Sorry bout the necro but could this work in the burst disc port? Or am I missing something?

https://ebay.us/m/IzRCnA

[DocsMachine]

No. The male thread id 3/8" pipe- which is roughly 1/2" OD. (The "pipe" part has more to do with the bore diameter than the thread diameter.)

The only way to put a gauge or fitting in place of a burst disc like that is to either re-tap the hole to take 1/8" NPT (which is tricky to do without damaging the reg body) or to make from scratch a fitting that fits the hole, and seals with a washer or thin O-ring.

I've done both, and for various reasons, am glad I haven't had to do it in a while.

Doc.

[FlightMedic938]

DocsMachine Ah ok, I think I get it now. Regardless, I abandoned the idea and found another spot for the gauge. If it weren’t for this thread I would’ve probably ruined the reg trying to get the gauge in.

[The Inflicted]

If anyone has a lead on flush-fitting plugs that would work in this space I would be glad to hear of it.