It's about as basic as it gets, but I reckon it looks somewhat like a rifle, and is stacks of fun to shoot!
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Basically it consists of;
Barrel; approx 55cm long, 17mm I/D copper pipe.
Chamber; 45cm 3/4" galv. riser pipe.
Valve; 3/4" ball valve
Firing mechanism; spring loaded leaver-release bolt lock....if that means anything to anyone!
Valve; shrader valve from a bike tube.
The firing mechanism is a piece of bar which replaces the original ball valve handle (the spring attaches to this), and a piece of rod joining it to another piece of shorter bar, with a hole drilled in it. This hole lines up with a small piece of metal pipe going directly through the wood, which a cuphead bolt slides into when the gun is cocked.
The bolt butts against the bent section of the original ball valve handle, which acts as a lever and pulls the bolt out of the hole in the bar, allowing it to turn, due to the tension of the spring, opening the valve.
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This is the gun when cocked; to fire you just push down (horizontally/towards the gun) on the red lever which pulls the bolt out from the "custom-built" ball valve opening handle.
As I said it's a pretty simple design, but it's comfortable and easy to aim, as you can look straight along the top of the barrel. We've found it's pretty accurate from about 20m; using trees with approx. 50cmx50cm targets scratched on them, we managed to get like 16/17 inside the target (most near the middle!), with he only exception being when I shot 5 marbles, and only one of them just missing the target!
Generally we've just shot at trees and beer bottles, but the accuracy is very surprising and it's easy to nail even pieces of the broken bottles!
When shooting at trees, the marbles more often then not stick in more then half. One particular tree we often shoot at has about 20 marbles lodged in!
Generally we pump it up to about 160psi, but it quite happily takes 230psi when we feel patient enough for the compressor to get it that high!
Anyway let me know what you think of it, or feel free to ask questions!
