Originally Posted by Belaslav
Sorry if this is offtopic, but I don't see the point.
Controlled firearm is defined by upper limits on muzzle energy (500fps) and muzzle velocity (5.7J), both has be exceeded for a barrelled projectile weapon to be a controlled firearm.
For a 0.20g airsoft BB to exceed 5.7J would require a muzzle velocity nearly 800fps. Basically, not going to happen with 99.9% of airsoft guns available in Canada. Kids are far more likely to shoot controlled firearms in the form of pellet guns at each other.
It is not illegal for kids to play airsoft, provided it is done in a regulated setting (i.e. paintball field) and with full parental consent. Whether that's a good idea is a matter for the parents to decide.