As you can see it's a co-axial barrel/reservoir design with a piston type valve.
It's built from 3" and 1.5" thin wall stainless tube made for pressurised steam. The other bits & bobs were turned out of HDPE. It barely leaks at all up to about 50psi, but above that the air whistles out all over the place. For higher pressures, I covered it in Hot Glue which has sealed it pretty good!
Filling is via this PCL connector and firing is achieved just by disconnecting the PCL, discharging the pressure in the void behind the piston.
At 180psi, it can achieve flight times of about 28 seconds. No idea what that translates into in terms of muzzle velocity or range - but it looks a lot!
Best ammo at this time of year is apples from the tree in my garden. If you use the barrel to 'core' an apple, it is an almost perfect fit and makes a good sharp crack sound upon firing, compared to the low thud you get firing most other things.
Si
