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cartridge fed pneumatic prototype

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: judgment_arms » Tue Apr 10, 2007 8:18 pm

If I’m understanding your designs right, what you have here is a blow-back airarm, pure blow-back to be exact, forgive me if this has already been said, you need to delay it, gas delay would be simple, not to mention a drastic improvement.

But still, I love seein’ revolutionary arms such as this, it gets me thinking.

Ingenuity is a dieing trait, 100 years ago if you needed a part, you made it, now days if you need a part and the hardware ain’t got it you think your screwed.

Now I need to thank you, you showed me that a pneumatic gun can have enough pressure and/or recoil to cycle an automatic arm.

Oh, and, putting a small spring in the magazine might solve your feeding problem.
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Unread postAuthor: Hawkeye » Tue Apr 10, 2007 8:31 pm

I don't see why it's unreasonable to think a pneumatic system wouldn't provide enough power to shoot two projectiles(bolt and ammo) in opposite directions(as an aside would this make the gun less likely to kick?)
By delaying the blowback I assume you mean holding the bolt tight against the cartridge until the projectile is definitely out the barrel. Jack has posted as to why the projectile will be gone anyway. The bolt system must be delayed a bit anyway by its heavier weight and increased friction.
I guess it would be fairly simple to have a cylinder behind the bolt that the blowgun could vent into and hold it forward a fraction longer.
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Unread postAuthor: joannaardway » Thu Apr 12, 2007 12:56 pm

jackssmirkingrevenge wrote:That makes sense, but it sounds very wasteful of air.

The design actually uses air that would be wasted anyway (all the excess air that's left after the projectile has gone), so the air it runs on is basically "free", and has no effect on air usage. (Other than the fact that the cylinder increases the chamber's volume a touch)

@Hawkeye: The kick would be delayed, but you'd still get the full brunt of it at some point. Momentum is always converved.
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Unread postAuthor: iknowmy3tables » Thu Apr 12, 2007 2:16 pm

him looks like Ive got some competion for cartridge you found a way to to have a blowback system. I want to compare this to my cartridge gun, what ejection method did you use jack?
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 12, 2007 2:28 pm

iknowmy3tables wrote:him looks like Ive got some competion for cartridge you found a way to to have a blowback system. I want to compare this to my cartridge gun, what ejection method did you use jack?


Very simple, as the cartridge is blown clear of the breech it strikes the bolt housing which is cut at a 45 degree angle towards the ejection port. This tips the cartridge out sideways, it's pretty much the same system used in any blowback firearm.
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Unread postAuthor: iknowmy3tables » Thu Apr 12, 2007 3:48 pm

intresting in case you haven't seen mine its a bolt action and the ejection is a screw that strikes rim of the coupling making it flick off
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 12, 2007 4:02 pm

Yep I've seen yours (I even commented on the thread ;p), very impressive :wink:
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Unread postAuthor: iknowmy3tables » Thu Apr 12, 2007 4:33 pm

whoops sorry
I geuss you didn't have to bolt lock to the cartridge, maybe ifI applied that 45degree ramp ejector to a rim locking bolt ought to be better
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 12, 2007 4:46 pm

my system doesn't require the bolt to hold the cartridge in any way, just like a simple blowback smg - the only reason i'd need a catch is to extract the cartridge manually in the even of a "misfire", but since firing doesn't actually depend on the cartridge, this is unnecessary.
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Unread postAuthor: iknowmy3tables » Fri Apr 13, 2007 11:25 am

ok anyways I don't fully understnd what joanna said about the air ram but then I came out with this after reading that
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edit whoops I forgot to conect the other side to the chammber
edit wait screw the diagram its faulty the pop valve should just be some neddle valve
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Last edited by iknowmy3tables on Fri Apr 13, 2007 3:07 pm, edited 4 times in total.

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Unread postAuthor: Solo » Fri Apr 13, 2007 1:34 pm

@joanna: dude, whoever thought your jack-hammer action up needs to be congradulated! That's slick. All the advantages of a bolt without the flow restriction of blow-forward or the woes of the blowback. Would you mind starting a thread on that thing?

@Jack: what exactly is causing the low power? Is it the air restriction through the cartridge, or the cartridge popping out the back, or does it have to do with the low pressure on the gun?
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Unread postAuthor: Hawkeye » Fri Apr 13, 2007 1:40 pm

I tend to think it's a combination of all three. It would be interesting to see it shot at a higher pressure with a longer barrel and appropriately shored up bolt system.
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Unread postAuthor: joannaardway » Fri Apr 13, 2007 2:29 pm

Solo wrote:@joanna: dude, whoever thought your jack-hammer action up needs to be congradulated! That's slick. All the advantages of a bolt without the flow restriction of blow-forward or the woes of the blowback. Would you mind starting a thread on that thing?

I'll tell my brother you liked it, and will start a thread - but I need diagrams first.
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Unread postAuthor: iknowmy3tables » Fri Apr 13, 2007 2:38 pm

wait a second that piston thing is more simple it sounds almost exactly like my idea only with a pneumatic return spring which i don't understand,
http://www.spudfiles.com/forums/gas-eff ... t6101.html ignore the needle and check valve it was for and old design idea (it was a double action thingy and was supose to refill by ball valve I later realized it wouldn't work) it was to slow down the reload speed while alowing it to dump the piston befor the next refill similar
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Unread postAuthor: joannaardway » Sat Apr 14, 2007 1:49 pm

Looks pretty similar, but as you said, your one uses a spring to return rather than the compressed gas reservoir of the Jackhammer system.
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