Home Made Air Gun

M

mwerner

Joined
Apr 23, 2002
Messages
5,354
Finally got around to putting together version one of my airgun:
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Close up of mechanism:

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Pretty crude, but it's mostly a test-bed. Simple ball-valve action, the ball-valve is opened by the spring and the trigger retains the ball-valve's arm.
I pressurize the air chamber to about 125 pounds with a few strokes of a bike pump.

This is a simple design, but quite effective; I've been shooting 1/2" marbles and they come out with authority. Whizzes through several sheets of drywall...
I plan to get some .45 lead balls and try shooting them patched.

I intend to build a more-potent and more efficient reciprocating-valve model, but I need to accumulate some plumbing parts.
 
Very cool! Doesn't matter how ugly it is as long as it can put lead downrange with decent ft lbs.
 
Wow! All you need is a better sort of valve.

I suppose you could make your own air powered shotgun.
 
As to the shotgun idea... There are a number of ideas floating around on the various videos and forums I look at. The cleverest I've seen so far is a self-contained shot "cartridge", a paper tube with wadding on both ends and a charge of shot in the middle. The airgun's barrel is modified to have a breech of sorts, just a piece of friction-fit tubing and a bolt that opens a port in the barrel.
To use, you insert the paper cartridge which has a piece sticking out the back. This folds over the breech when it's closed. When you fire, the wads and shot go downrange and the paper cartridge stays in the gun, ready to be re-used. At least in the video, the shot charge was quite effective!
I imagine you could use small-bore shotgun-shell charge cups if you could find a properly-sized tube for the barrel.

The reciprocating-valve assembly seems to be the most efficient idea in current use; it's also called a "piston valve". Took me a while to figure out how they work, but it's essentially pretty simple. The piston seals the bore from the main air charge, and communicates with a small air chamber to the rear which is trigger-controlled. When you activate the trigger, that small supply of air is exhausted, forcing the piston to the rear to allow the main charge of compressed air to go down the bore.
With common plumbing parts, very high pressures can be managed. There's one on YouTube that operates at 1200 psi plus!
 
That's pretty neat. I've made a few potatoe cannons but never anything like what you've made. The closest was an air cannon made from pvc and a blade valve from an RV's greywater drain. It worked great for firing golfballs and empty caulking tubes.

Can't wait to see your next one!
 
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