23 mm ID 27 mm OD aluminium tubing
Burst disk holder with M 12 threads, made out of aluminium.
The back plug is the same red PVC as my piston, and with 2.5 cm. thickness it should hold 1000 psi...

8 mm burst disk to keep things simple and reliable. I just pop the projectile in the front of it.
Maybe I can ask my teacher to buy the materials from the school and put it in the CNC-lathe, to make a nice amount of them.
Just some ideas floating around in my mind....
With a 100 cm 8mm barrel it should give about 180 joules, pretty nice.
Im now designing a gun around it.... I think semi- or full automatic has some power loss because of the cartridge popping out?