CO2 the whole gun will be designed to work at much lower pressure & because of the way the different gasses act (CO2 becoming liquid under pressure)...
Large fishing weights hung with a wire trace on the loop tied to thick fishing line. Attach a weight to the other end, throw over a branch etc. Use a...
And you can get into a "vicious circle scenario", where fierce acceleration creates very quick pressure build up, with higher temperatures and higher...