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Gun shells

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Gun shells

Unread postAuthor: turbohacker » Fri Mar 16, 2007 11:49 pm

any body have an idea for a gun with reloadable cartrages? I was thinking something along the lines of a trggered burt disk that was triggered with a pointed arrow of some sort. The whole idea for the gun is to have every thing, chainber valve and barrel with projectile, in one assebly so that reload will be extremly simple. Any thaughts? :?:
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Unread postAuthor: jackssmirkingrevenge » Sat Mar 17, 2007 12:02 pm

There are commercially available air weapons that use air cartridges, like the Brocock Air Cartridge System:

http://www.talarms.co.uk/brocock_air_ca ... ystem.html

However these use almost 1,000 psi of air and are not a very practical idea for the home builder, as well as being quite complex if one were to make them in quantity.

I suggest you look to combustions for a completely self contained, easy to make cartridge - here's one I designed and made:

Image

and a video of it in action, with the spent cartridge ejecting:

[youtube]http://www.youtube.com/watch?v=V4q8QJr412Y[/youtube]

how it works:

Image
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Last edited by jackssmirkingrevenge on Mon Mar 19, 2007 6:01 am, edited 1 time in total.
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Unread postAuthor: A-98 » Sat Mar 17, 2007 12:17 pm

wow, thats very nice. how well does it work?
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Unread postAuthor: frankrede » Sat Mar 17, 2007 12:18 pm

Thats interesting/ Have you prefected it enough to be used in a auto reloading system?
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Unread postAuthor: A-98 » Sat Mar 17, 2007 12:22 pm

also, how do you meter the proper amount of fuel into that small of a chamber?
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Unread postAuthor: boilingleadbath » Sat Mar 17, 2007 6:37 pm

I figure the chamber volume is about 50 cm<sup>3</sup>.
(feel free to correct me there)

That equates to about 2ml of propane.

I'd expect one of the small syringes (say, the 10ml ones) would meter the gasses with acceptable precision.
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Unread postAuthor: us sniper » Sat Mar 17, 2007 7:18 pm

How big would those shells that you designed be? Would they be launching bb's or potatos
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Unread postAuthor: VH_man » Sat Mar 17, 2007 7:20 pm

Thats pretty cool............... AIRSOFT SNIPER TIME!!!!!!!!

sorry...... you gave me a pretty amazing idea..... gonna try that when i finally get home.........

Does the cartridge actually eject itself with a light projectile in the barrel? otherwise i will make this bolt action........
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Unread postAuthor: us sniper » Sat Mar 17, 2007 7:28 pm

For the shells you could alos try having a sponge soaked in a flammable then a short chamber, then the projectile. Then all you would need is something hot to cause it to explode. To make sure that the explosion goes foreward,you would have the hot object encompass the whole shell. All you would need to replace is the sponge and the projectile.
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Unread postAuthor: Mr.Russ » Sat Mar 17, 2007 7:48 pm

What about the nerf haven gun? that has a good shell/ejection system.

http://nerfhaven.com/homemade/boltsniper_far/#plans
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Unread postAuthor: us sniper » Sat Mar 17, 2007 11:30 pm

i think that turbohacker wanted to make sometihng that was more like a gun, where the power is generated by the shell, not a spring.
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Unread postAuthor: Mr.Russ » Sun Mar 18, 2007 12:43 am

ohhh i see. i misunderstood it.
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Unread postAuthor: jackssmirkingrevenge » Sun Mar 18, 2007 6:34 am

There's a whole thread about my design somewhere in the archives of spudtech.

Even with a light projectile (I used a 3 gram shotgun wad in the video) enough pressure is generated to eject the cartridge, while still firing the projectile. As boilingleadbath assumed, I use a syringe to meter around 4 ml of butane/propane through the mouth of the cartridge.

Image

The idea was to incorporate the cartridge into a self-loading design, but there are a few snags - you can't have a spring loaded magazine, because this will create too much friction and not allow the cartridge to eject. This means that the next round has to be gravity fed, but the problem is that it doesn't feed fast enough to be seated by the returning breech if it's spring loaded. What I did therefore was to have a pneumatic piston that returned slower than a spring and whose compression could be varied by altering the reservoir pressure.

The original design:

Image

final prototype with pneumatic breech:

Image

Image

Image

Image


The project was halted due to lack of interest, though what with the spudfiles competition on the cards, I might just be persuaded to develop it further...
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