i´m just makeing cheap test version

,chamber is 1/2l and barrel is 15mm copper pipe and valve is going to be bust disck...
chamber is 48.5mm seamless steel pipe, i lathed endcap and bushing for 1/2"threads, then my friend welded them.water is loaded through union and i will lathe teflon ring to be sure that union will not leak .
i heat the cannon with Propane or Coals. ... and if this cannon is power full and worth a lot of time then i`m makeing new and much better one =D and if somebody dont know how it works:i put little water in the chamber than i heat it
...do you think i can use 0.4l co2 bottle for the chamber it would look better then the chamber that i made:?: