9mm Coaxial airgun

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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Juggernaut12121
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Thu Jul 03, 2014 7:49 am

I've wanted to build a smaller bore airgun for a while, I also wanted it to be more compact although that didn't work to well for me :P . I still like it though
The barrel is a length of aluminum round tube that's 3/8'' in ID (not exactly 9mm but close enough with wadding) and almost 1/2'' in OD by 3' long
Chamber is a 2' section of 1 1/4'' pvc pipe
The piston is a 3/4'' pvc cap filled with hot glue and topped off with a piece of sheet rubber (sorry I don't have a picture)\
I wanted to keep it somewhat small and simple so the pilot valve is a 1/4'' ball valve, and I need to attach a thingy onto the quick adapter on the other end of the ball valve
The backstop is a layer of weather sealing tape
I haven't gotten to really shoot it yet since the ammo is still in the mail, but it seems to work pretty well.
The stock is alright but in retrospect I probably should have used 3/4'' pipe and fittings instead of 1/2'', which I had lying around.
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Gun without stock
Gun without stock
The pilot valve and fill port, the male quick connect is placed at a 45 degree angle down so that air doesn't blast your hand while it's in the stock, and a metal bushing behind the foam backstop
The pilot valve and fill port, the male quick connect is placed at a 45 degree angle down so that air doesn't blast your hand while it's in the stock, and a metal bushing behind the foam backstop
The thingy I mentioned earlier, it's just a female quick connect and a Schrader valve attached together with a 1/4'' nipple
The thingy I mentioned earlier, it's just a female quick connect and a Schrader valve attached together with a 1/4'' nipple
The gun placed in the stock, the black thing near the back of the gun is a zip tie used to anchor the back end down, and the male adapter up front is to attach a barrel shroud or similar, and I want to place a red dot sight I have lying around on top of the gun
The gun placed in the stock, the black thing near the back of the gun is a zip tie used to anchor the back end down, and the male adapter up front is to attach a barrel shroud or similar, and I want to place a red dot sight I have lying around on top of the gun
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fractal
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Thu Jul 03, 2014 4:42 pm

Looks well constructed
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Juggernaut12121
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Thu Jul 03, 2014 5:03 pm

Thank you :D
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jackssmirkingrevenge
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Sun Jul 06, 2014 7:46 pm

Nice effort! For a small bore personally I would have gone for higher pressure and a smaller chamber volume, you would be amazed at the difference in performance.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Juggernaut12121
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Mon Jul 07, 2014 10:05 am

Thanks! I would've made something more high pressure (out of copper or something similar) but I didn't have any way to pressurize it past 100 PSI (I have a floor pump and a small air compressor). Unless I'm missing some sort of technique or something (highly possible for me to be missing important or obvious knowledge)
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fenrir
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Mon Jul 07, 2014 11:05 am

You can make a stirrup pump, or salvage a fridge compressor in order to reach higher pressures.
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Juggernaut12121
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Mon Jul 07, 2014 2:35 pm

Thanks! I've never heard of a stirrup pump before a few minutes ago, that'll probably be my next project


Edit: after looking a while I've figured out that I just called them something different, but I've never thought of building one
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jackssmirkingrevenge
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Mon Jul 07, 2014 8:33 pm

You can buy a floor pump that goes to 260 psi for not much $$$:

That will more than double your available power...
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Juggernaut12121
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Thu Jul 17, 2014 4:02 pm

I thought about getting a shock pump for getting higher pressures in future guns, I found one for decently cheap (boasts 400 PSI)

Although I don't have any experience with them, I don't think they should be too hard to use

Btw JSR your picture and your quote are awesome
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fenrir
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Thu Jul 17, 2014 5:14 pm

Just don't use very large volumes. If you live in the US, I can send you mine for 25 dollars shipped, just PM me.
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