New and the last gun design.

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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Mitchza89
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Sun Jan 20, 2008 1:59 am

Well this is my latest design for this will be one of my last guns. It's based off the S400 and the SSS that Chaos previously built. I hate copying designs at all but his design is the most practical and clean for me. I take my hat off to Choas for first making what he did.

This is the idea I had planned:
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Zen///
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Sun Jan 20, 2008 2:10 am

Dident you call your last gun "the last gun"?

Just check GGDT to optimize it before you start building.
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Mitchza89
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Sun Jan 20, 2008 2:13 am

Yeah "the last gun" was my last small bore, this will be my last larger bore gun ;)
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Sun Jan 20, 2008 2:46 am

Looks good, Chaos will be proud!
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Mitchza89
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Sun Jan 20, 2008 3:02 am

Cheers mate, thanks alot. Can anyone see anything that I could do to improve the design? I'm thinking of getting some 1/4'' copper tube and running that along the gun from the blowgun to the piston valve. it should give it a really nice look and feel. :D

Edit: Velocity told by GGDT:

100psi: 560fps
200psi: 747fps
300psi: 866fps

Not too great :(....
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ALIHISGREAT
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Sun Jan 20, 2008 5:16 am

to imporve the design... hmmm well a QEV pilot would be a start if you are running at suitable pressures and the barrel obviously could be longer... and if you ditch the stock you could make the barrel longer, but the one thing i would reccomend to up the power is to up the pressure.

p.s. whats the ammo you will be using?
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Mitchza89
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Sun Jan 20, 2008 5:18 am

Well 300psi is about as high as I would go, maybe 350 if the pump I'm gonna make can take it. Qev's are very expensive to get in Aus :( I'm gonna make the barrel 120cm instead of 100cm and take the chamber from 50cm to 75cm.

Primarily, marbles will be what's used.
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ALIHISGREAT
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Sun Jan 20, 2008 5:28 am

Mitchza89 wrote:Well 300psi is about as high as I would go, maybe 350 if the pump I'm gonna make can take it. Qev's are very expensive to get in Aus :( I'm gonna make the barrel 120cm instead of 100cm and take the chamber from 50cm to 75cm.

Primarily, marbles will be what's used.
hmm marbles so they are about 7g.... well i have been planning something similar for a while and i'm using a 20mm copper barrel but 150cm long and i'm using a 28mm x 22mm x 28mm reducing tee (barrel side will be 22mm) with a 25mm piston and a 50cm x 28mm copper chamber at 400psi piloted by a 1/2" qev which won't be that much more powerful than your design because i think pneumatics reach a point where it is very hard to go over because normal air is reluctant to go over the spped of sound :roll:
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Mitchza89
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Sun Jan 20, 2008 5:32 am

:? 7grams?! I was told a standard glass marble was only 4... Hmm... Your gun at 400psi will be absolutely insane. When is the release date for this beast?
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ALIHISGREAT
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Sun Jan 20, 2008 5:57 am

Mitchza89 wrote::? 7grams?! I was told a standard glass marble was only 4... Hmm... Your gun at 400psi will be absolutely insane. When is the release date for this beast?
hmm i though it was paintballs that were in the 3-4g region :? maybe i'm wrong.... and i'm still thinking about whether the cannon will be worh the cost (which is alot :cry:) but i will hopefully order the parts soon... and yes it will be insane... more power than a .22 rifle :twisted:
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Mitchza89
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Sun Jan 20, 2008 6:01 am

Hmm with the gun I'm gonna build, what do you think the penetration will be like with a marble at 300psi?
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ALIHISGREAT
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Sun Jan 20, 2008 6:10 am

Mitchza89 wrote:Hmm with the gun I'm gonna build, what do you think the penetration will be like with a marble at 300psi?
well a marble at 300psi will be going at 866fps according yo your calculations but i really don't have a clue about penatration but i can work out muzzle energy and momentum?

muzzle energy= just over 100ft/lbs

momentum= 0.004kg*264m/s= 1.056kgm/s
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Mitchza89
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Sun Jan 20, 2008 6:11 am

Haha well is 1.056kgm/s good? :P
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ALIHISGREAT
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Sun Jan 20, 2008 6:15 am

well i will get 2.something kgm/s with a 7g projectile fired from my 400psi beast (hopefully) so no :P thats because you will be firing a lighter projectile slower (a 4g projectile at 264m/s) wheras i will be firing a heavier projectlie faster (7g at 304m/s)

i might go work out how much momentum DYI's sbtakkankvnfk has...

edit: although the marbles fired from your gun will have more momentum (just) than .22 rifle bullets

40grain= 0.858kgm/s
38grain high velocity= 0.95kgm/s
31grain high velocity= 0.88kgm/s
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Sun Jan 20, 2008 2:50 pm

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