Semi-Auto Shotgun

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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Lockednloaded
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Sun Mar 28, 2010 3:33 pm

This is the same basic design as my earlier semi-auto project witha small twist... Instead of having a large chamber volume, I have compacted this gun as much as possible by adding a kobalt 20 oz CO2 regulator.
For compactness sake, the barrel is only as long as the rest of the launcher, this way, when carrying it the barrel can be removed.
I use this gun at 120psi, and every tim i pull the trigger 40 psi is lost.

Now for some pictures:

The Whole Gun
Image

Valve Area
Image

Valve Area+CO2 reg
Image

Looking Down the Homemade sights
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clemsonguy1125
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Sun Mar 28, 2010 4:40 pm

Pretty cool, have you thought about adding a magazine so you shoot it truly semi-auto
That is all.
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STHORNE
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Sun Mar 28, 2010 5:15 pm

very nice. have you considered converting it to an over-under structure to conserve space or do you hold it like a fire arm?

otherwise, very nice build. and yeah a magazine would be cool like clemsonguy1125 said.

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Lockednloaded
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Sun Mar 28, 2010 7:12 pm

A magazine will be added when consistent shells are made, but for now its wadding bbs wadding.
I wanted todo an over under setup at first, but this was made of all spare parts which you can tell by my endcap setup. So now i use the end as a shoulder stock.
The only improvement besides that is that i will add a grip to make pulling the trigger easier for people who have never fired it before because its fine for me.
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whitexnightjp
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Sun Mar 28, 2010 9:22 pm

isnt it bad to put C02 in a pvc chamber. (thats wat ive heard, i could be wrong) but yeah i like it. I am also working on airsoft shotgun. What do you use for wadding? and also do you think you could put up some damage shots?
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Lockednloaded
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Sun Mar 28, 2010 9:44 pm

It is perfectly safe in this application, the 1" PVC is rated near 300 psi, the pop-off is set at 125 psi, the regulator can't go past 120 psi, and it is not rapid fire so the co2 doesn't freeze my pipe which I doubt it would in our hot Texas weather. Damage shots will have to wait airsoft wise, I'm all out of bbs and curently using grapes, but I can assure the little guy packs a much larger punch than expected. For wadding I use toilet paper, but I will switch to shells as soon as possible.
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Gun Freak
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Sun Mar 28, 2010 10:04 pm

LnL I think you need to change you sig. :D
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Lockednloaded
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Sun Mar 28, 2010 11:20 pm

Hmm.. True, I'll probably move it to "in progress" because there will be many more updates to come
p.s.
I really like the black and blue theme on the sv, so do you think I should make the whole launcher a black and blue "cammo" and by this I mean no defined lines in my painting. I think this would give it a cool urban camo look
p.p.s
anyone got any good ideas for reusable shells, not empty 12 gauges though because I don't have access to those
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Gun Freak
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Mon Mar 29, 2010 10:24 am

Have you tried paper shells?
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Lockednloaded
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Mon Mar 29, 2010 10:48 am

Well gunfreak I don't like paper shells for two reasons: 1. They are not reusable. 2. They don't always act in a shotgun like manner, I've had them stay together and hit the target with a trremendous force, and I bet you can all see why I wouldn't want this kind of dangerous inconsistency when firing at a real human being
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SEAKING9006
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Mon Mar 29, 2010 11:30 am

Try shells made from thinwall (ex. SDR-21) pipe and attach a rim to the end. I'm using SCH-40 for rimless shells on my nerf rifle.
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deathbyDWV
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Mon Mar 29, 2010 12:33 pm

Yeah you need a loading mechanism and some damage pics.
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Lockednloaded
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Mon Mar 29, 2010 1:28 pm

A loading mech will be tough, i plan on using a shell with a lip on the back like an actual shot gun. This way the shell will not shoot out, just the bbs. It will consist of a washer the same OD as the barrel and a thinwall pipe with the same OD as the barrel's ID. Each side will be covered with foil tape and the shell will be filled with wadding and shot.
So for a loading mech I will probably go with a break-barrel setup, that seems to be the best way to go about this
As for damage pics, i will have some up, but probably not airsoft related. I do have some pictures of a grape stripping the bark of of a tree, and i might find a suitable target to shoot one of jack's co2 shells.
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Gun Freak
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Mon Mar 29, 2010 1:46 pm

Sounds good, but it will take a while to get right.
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Lockednloaded
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Mon Mar 29, 2010 1:49 pm

I've got a solid breakbarrel system working for me i will post a diagram of it soon. For now here are some damage picture at 120 psi with a grape:
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