considering CA has pretty lenient laws on them..........
CO2 isn't combustion.
The portion in bold used to say something along the lines of"any chemical reaction or force"
ive seen them up to 50cal. yes your could kill a person with one, but from what ive read they are still classified as firearms as far as carrying them goes
now if you look up the term "firearm" in the dictionary you get "A weapon, especially a pistol or rifle, capable of firing a projectile and using an explosive charge as a propellant."