I upgraded my gun with a bipod and a scope. it shoots quite accurate, I can hit a soup can from 10 meters away. I shoot trough both sides of the can. http://img695.imageshack.us/img695/8404/p1050996p.jpg http://img528.imageshack.us/img528/1226/p1050997.jpg As you can see, my cat likes the gun too.

Thank you for the explanation!
it made the construction of a piston valve much more clear for me.
:salute:

i've searched for a long time to find the right PVC-pipe. its pretty thick walled and doesn't have a cellular core. the end caps are made out of 5-6 MM thick pvc. I run the gun up to 90 PSI. I shoot with anything that fits the barrel. I like the trigger as it is now. If I put it on the other side it...

It has a 12 mm barrel. I think it's about .50 cal.
I designed the valve opener myself. it's based on my earlier crossbow designs.
when I pull the trigger when i've filled it up with air, the only thing I hear is a bang, so I think it works pretty good.

It's quite a large gun. (1.60 meters, +- 5 foot)
I made a scope for it with an old disposable camera. it works pretty good.

Great gun!
Are you planning to make a video of it?

This is the third airgun I have made. I started three years ago with a simple soda bottle with a ball valve. The second one I made had a PVC pressure chamber and also a ball valve. This one has the same pressure chamber as the second one, but I made a trigger for it so it has a much shorter opening ...