Posted: 03/16/2007 22:49 PM Post subject: Gun shells
Major
Joined: 19 Dec 2006 Posts: 394 489.56 Spud Bux
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?
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:
and a video of it in action, with the spent cartridge ejecting:
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.
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.
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:
final prototype with pneumatic breech:
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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