the air cartridge we wanted

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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Anatine Duo
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Thu Mar 10, 2022 4:27 pm

Joerg's new toy.

I fooled around with this cartridge design decades ago but gave up because it was long before 4500 psi handpumps were available. This sparked interest in it again, maybe with a 40mm size cartridge 8-) ... maybe rimless for better feeding in JSR's brain.


iknowmy3tables
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Sun Mar 13, 2022 12:13 pm

any clue on how the cartridges on the defensive pistol work?
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ckman
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Fri Mar 18, 2022 9:17 pm

Thank you for sharing this video - I didn't know that these cartridges existed. Surprisingly, I was unable to find an internal diagram, so I ordered a couple of them and will post photos of the internals when they arrive.
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jackssmirkingrevenge
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Thu Jun 16, 2022 3:32 am

Interesting stuff! It seems to go around laws restricting barreled weapons by effectively being a spigot gun without a "barrel" per se.

I've found a picture of the cartridge internals:

Image

My impression is that it is the exhaust valve piston design we all know and love, with the pilot valve being a burst disk.

I'm guessing it's because of the difficult of actuating a resettable pilot valve at such high pressures.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Solar
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Sat Jul 02, 2022 8:25 pm

Interesting stuff but we all don't love exhaust valve piston designs. Relying on the launcher never to leak to prevent a misfire is not ideal.
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jackssmirkingrevenge
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Sun Jul 03, 2022 4:48 pm

That's true, although for most of the setups we see on spudfiles a slow leak would not be sufficient to pilot the valve, as it's rare that the the piston or diaphragm is a perfect seal, especially without the shock of a sudden pressure imbalance.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Solar
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Sun Jul 03, 2022 7:09 pm

True, but I quit using them after a misfire from merely degassing the launcher as apparently the pressure behind the diaphram leaked out faster than the ballast side and there was enough pressure left to lob a round into the neighbor's yard. Luckily no one was hurt and no damage to any property but it could have been a lot worse.
Dembouz921
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Sat Jul 16, 2022 6:11 am

I dont understand how the main valve works (i believe it is the white thing with the spring), it must be something like a 2 way QEV with the burst disk acting like a pilot valve, but how does the valve open after the burst disk is pierced?
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jackssmirkingrevenge
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Mon Jul 18, 2022 9:58 am

Take a look at this thread, plenty of examples on the same concept.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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