I'd love if I could get authorisation for some events cuz I have the drawings all together and a shopping list ready, but held off until I got some feed back. It seems a silly to disallow combustion weapons when they're very simple to contain. I'll be using a co2 paintball tank as the cylinder, with all the pressure and exhaust gases vented at the end of the power stroke. The bottle would never store more than 150 psi. and would need barely any fuel in a tank. The 500ml limit would be ridiculously oversized for this use.

Pneumatics are far more dangerous me thinks