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Automatic Grenade Launcher (Airsoft/Paintball/Nerf)

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Automatic Grenade Launcher (Airsoft/Paintball/Nerf)

Unread postAuthor: Davidvaini » Fri Apr 24, 2009 5:17 pm

Hey I am still working on the model and design, but It is a basic QEV with popoff design for the automatic firing. I still have to add the pop-off between the trigger and the qev.
Image

It would feature a 3/4" QEV but fire 1.75 inch Nerf Ballistic balls shown below:

http://images.entertainmentearth.com/%5 ... 1348lg.jpg

The balls are really light and don't really require much flow to shoot them. So I decided to opt for a 3/4" QEV or even a 1/2" QEV.

The cycle chamber would be on the top because I plan on encasing all of this into a body to make it look like the MK19 Grenade Launcher:
http://www.globalsecurity.org/military/ ... s/mk19.jpg

The magazines would load into a basic T and will be spring fed. There will be an adjustable barrel stop/hopup right After the T.

What do you guys think? Think I should go ahead with the build?
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Unread postAuthor: Brian the brain » Fri Apr 24, 2009 5:22 pm

Yes you should!

We need to explore the possibilities of QEV-pop-off designs!

And wait till your airsoft buddies see it!
The look on their face! :D

Build it!!!!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Davidvaini » Fri Apr 24, 2009 5:30 pm

Do you think the cycle chamber size is big enough or too big?
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Unread postAuthor: jackssmirkingrevenge » Fri Apr 24, 2009 5:32 pm

Davidvaini wrote:Do you think the cycle chamber size is big enough or too big?


It depends what pressure you're operating at and what sort of power you're after, but it should work nicely. If you're going to use it for airsoft some sort of quick change mag would be a good idea.
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Unread postAuthor: Davidvaini » Fri Apr 24, 2009 5:35 pm

I would be using it relatively lower pressures. I think around 120 psi if not a little less.

Right now the thing sticking out the side is the magazine. It would be a simple tube with a cap on the end and something to hold the balls inside.

The challenge is finding the right size PVC for the barrel and magazines.
1.75" ID Pipe would be ideal.

EDIT: I'm on chat right now if anyone wants to help me or make suggestions.
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Unread postAuthor: dewey-1 » Fri Apr 24, 2009 5:41 pm

That QEV and trigger drawing sure looks familiar!

I sure wish I had a pop off valve so I could update the library.

Looking forward to seeing your final configuration.

If you could find some SDR 32.5 or maybe SDR 26
in 1.5 inch diameter, you could use it as a sleeve in sch80 2 inch.
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Unread postAuthor: Davidvaini » Fri Apr 24, 2009 6:18 pm

what is the actual ID of SDR 32.5 or sdr 26?
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Unread postAuthor: sputnick » Fri Apr 24, 2009 6:23 pm

I think it looks good, I can't see any problem with it,

The only thing, (as always,) is preventing double feeds, but I suppose that could be easily remedied with a ball detent.

But I would say, since you're using pretty light ammo, why not just use a flap that closes off the mag when air is flowing, that could work no? I'm pretty sure that was used on a full auto marble QEV gun posted a while ago, but I'm not sure as to whether it would work with a spring fed mag.

I say go for it, and dress it up to look more like this... Image


With a tripod and everything, then you could REALLY show it off.
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Unread postAuthor: dewey-1 » Fri Apr 24, 2009 7:00 pm

1.5 inch SDR 32.5 is 1.760 inch nominal ID. {1.740 to 1.780}

1.5 inch SDR 26 is 1.734 inch nominal ID. {1.714 to 1.754}

The range shows the tolerances.

By the way, I think you are the first to use my parts library.
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Unread postAuthor: jonnyboy » Fri Apr 24, 2009 7:09 pm

Nice idea, although in my mind a semi auto would be more efficient. As far as feeding goes something like a blow forward bolt but with some modification could allow both semi and automatic modes.

@sputnick

David posted that same picture in his op.

@david

Did you ever end up making the laser tripwire from the plans I sent you?
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mobile chernobyl wrote:I can shoot a Canuter Valve off my '82 Chevy Ram F150 AT LEAST 3/4 Mile with 'ma cannon made of soup cans duct taped together, then I just squirt some bacardi 151 in the chamber and hold up my cigarrete lighta and WHOOSH! That thing flies at least 3/4 mile
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Unread postAuthor: sputnick » Fri Apr 24, 2009 7:12 pm

jonnyboy wrote:@sputnick

David posted that same picture in his op.



I am aware, that is why I used that picture :roll:

It was supposed to be telling him that if he really did make it up like that, it would be the best.

And BTW, I think you should make it paintball, just my 0.02$
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Unread postAuthor: Technician1002 » Fri Apr 24, 2009 7:23 pm

Davidvaini wrote:I would be using it relatively lower pressures. I think around 120 psi if not a little less.



Those plastic balls may collapse at 120 PSI with a fast valve. May want to go larger orifice valve at lower pressure and size the chamber for a positive pressure on projectile exit. To pull it off may require designing and building your own low pressure pop off valve.
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Unread postAuthor: Dgealy » Fri Apr 24, 2009 8:01 pm

When I have shot light balls like the ones you show there, always one side has caught the barrel more than another, so it generated random spin in one direction or another, making it absolutely useless.

I'm not sure if these would do it, but that's just my experience.
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Unread postAuthor: jonnyboy » Fri Apr 24, 2009 8:39 pm

sputnick wrote:
jonnyboy wrote:@sputnick

David posted that same picture in his op.



I am aware, that is why I used that picture :roll:

It was supposed to be telling him that if he really did make it up like that, it would be the best.

And BTW, I think you should make it paintball, just my 0.02$

Well the text you posted before the picture gave the impression that you should make it look like the picture, except you didn't point out anything to add.

I don't think he plays paintball so it wouldn't be very practical.. but you could use it for both.

When I have shot light balls like the ones you show there, always one side has caught the barrel more than another, so it generated random spin in one direction or another, making it absolutely useless.


Could this be from a seam in the middle?
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mobile chernobyl wrote:I can shoot a Canuter Valve off my '82 Chevy Ram F150 AT LEAST 3/4 Mile with 'ma cannon made of soup cans duct taped together, then I just squirt some bacardi 151 in the chamber and hold up my cigarrete lighta and WHOOSH! That thing flies at least 3/4 mile
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Unread postAuthor: Strigol » Fri Apr 24, 2009 9:19 pm

When I have shot light balls like the ones you show there, always one side has caught the barrel more than another, so it generated random spin in one direction or another, making it absolutely useless.


Easy fix to that is making a hopup for the balls to control spin, which I'm sure david knows about
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