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Jspb Semiautomatic Barrel


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#1 3DBBQ

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Posted 13 July 2004 - 03:30 AM

http://www.nt3.idv.t...yw/sabarrel.htm
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#2 Doom

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Posted 13 July 2004 - 10:07 AM

I get that the check valve like thing will only let a certain amount of air through, good idea. That would help ration the air, but what I don't get is how this is semi-auto because you would have to put the dart down the barrel again, which doesn't even have a breech so you would have to jam it down the barrel. I also think it would be quite hard to modify a check valve to do that, in fact I think you'd be better off building that valve, which likely would turn out cheaper.

Do you have a working model?
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#3 ShortShit

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Posted 13 July 2004 - 12:35 PM

Ok I get it, it does the action in your video REALLY FAST, so a burst of air gets out of the tank, and seeps into the barrel having a dart shoot. reload, and then tap the trigger to get another burst. and you get several fast short bursts as you please making it kinda semi auto. It would be ideal to have one of your barrel clip designs so you wouldnt have to reload all the time but Im sure your taking that into consideration. It looks a little risky but worth a shot if you could get it to work for sure. Good luck!
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#4 Vintage

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Posted 13 July 2004 - 04:01 PM

3DBBQ, it won't work. According to your design, all the air will be lost in the first shot. The air will come out the hose nozzle, hit the rubber pad, and go right into the barrel and out. The air won't continue to push the rubber pad forward, because pressurized air tends to take the "easy route" (the barrel).

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#5 cxwq

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Posted 13 July 2004 - 04:21 PM

I think it could work quite well. The air doesn't need to continue acting on the mechanism because momentum would carry it forward after the initial shove. The speed of the action (and thus the airflow duration) could be adjusted by changing the relative diameter of the various pieces and the length of the mechanism. The volume of airflow would be adjusted by changing the size of the barrel air inlets.

The added advantage here is that you get the entire barrel physically cycling forward and backwards which leads to interesting magazine possibilities.
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#6 Ragornocks

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Posted 13 July 2004 - 04:47 PM

In other words, you don't release all the air out of the hose handle, right?

So long as you could regulate the air before it got to the check valve, it looks good.
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hug the fuck out of 'em, philippe!

#7 Vintage

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Posted 13 July 2004 - 05:19 PM

Yes, cxwq, but your view only works if there is no spring to return it to it's original position. Without a spring, you would have to manually pull the barrel back to its starting point.

This concept would be air-consuming, because once the rubber pad stops air-flow, you must return the barrel back which loses the extra pressure in that chamber. Also, the pressure would drop greatly with each shot, making a dual-valve system much better.

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#8 okto

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Posted 13 July 2004 - 06:31 PM

to use that with a magazine you'd have to get it to fire when the check valve is all the way closed, so the barrel would be as fare forward as possible, and have the barrel shown in the animation actually be the breech for another barrel and seal against it.
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#9 Ragornocks

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Posted 13 July 2004 - 07:27 PM

Simple solution to the whole "barrel" thing. Just don't use that as the barrel. Make it shorter, and make it lead into the barrel, which has a larger I/D. This means that the small piece that was the barrel will be moving, but the actual barrel will not, meaning you can incorperate that clip system without any problems.

Posted Image

The more I look at it, the more I like it. The air is regulated by the hose handle, the check valve keeps it moving one way, and it has room for lots of improvement.

Just find an effective way of making the barrel reloading via a clip system, and add a constant air source (IE, an HPA Tank), then you have something that is capable of some major foamy action. With the HPA tank, you are able to use the inline regulator to control pressure, and it is more stable than Co2, plus more effective than a simple PVC compressed air tank.
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hug the fuck out of 'em, philippe!

#10 ShortShit

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Posted 13 July 2004 - 09:44 PM

yeah I was thinking about that type of barrel adjustment myself. I really like this idea and Rags input. I think this could be a really cool thang for homemades if we can get some functional prototypes goin... which im sure 3dbbq is...
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#11 okto

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Posted 14 July 2004 - 01:07 AM

HPA? what and where obtainable and how big and how expensive?
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#12 Ragornocks

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Posted 14 July 2004 - 09:43 AM

HPA is High Pressure Air (or sometimes Low Pressure, depending on the variant). They are specially made tanks, usually used in paintball, made to store compressed air or nitrogen up to 4500psi. Because there is no liquid, and the tank has a regulator on it, it is very stable.

They run from about $80 for a steel 40ci to around $400 for a Smart Parts Air w/ Max Flo. You can snag a decent one for about $150-160.

You could skimp out and use a $20 Co2 tank, but they are very unpredictable when it comes to pressure ratings. Fluxates way too much.

EDIT: Gah, changing it to the way I did it makes it so you can't use most kinds of clips. You'd have to use either a gravity fed or a spring right on the barrel. Hmm...

Edited by Ragornocks, 14 July 2004 - 10:14 AM.

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hug the fuck out of 'em, philippe!

#13 somebody

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Posted 17 July 2004 - 09:58 PM

this look similar to the design i'm currently working on, which is based on the blastfire, except the my design would use multiple barrels, each with a valve, like the blastfire.

and i agree that the two valve sytem would work better, and take less tinkering than this system. the fact that there is a stage where the valve is completely open is the problem, because you rely on the speed of the hose trigger to keep all you pressure from rushing out. if you want a valve without this problem, why not just use the semi-auto valve by zero, in the mods section of this very site :
http://www.nerfhaven..._semiautovalve/

ok, i know that you just wanted a critique of a new idea, but if you're trying to build a gun there you go.

and it would be awesome if you actually got a valve like that to work, despite all the doubters have said.
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