Copper Pneumatic Air Cannon

Step 7 Fire!

My favourite ammunition for a 22mm barrel is an empty 12g CO2 cartridge. But you can use anything which fits in the barrel. Close the ball valve, pump it up and release the valve. Power will change depending on how big you made your gun. The faster you open your valve, the better your shot will be. Pumping your gun with the valve open results in cool compression condensation rings. Have Fun! and be safe.

There are several places to find out more across the web.
*UKSGC
*Spudtech
*Spudfiles
Are probably the 3 largest