actually the classification of firearms in canada mainly rests on muzzle velocity and ballistics. Since paintball markers shoot under 500 fps then they are not classified as firearms. Just think if they did it would have to be registered, you would have to get a PAL (new version of FAC) and permits. PLust be over 18, plus no record, plus notplaywith it within city limits, plus follow all the transportation rules and regs.
Also think of it this way if paintball markers become firearms the liberals will take them all away because under the law they are all too short, no stocks (without being removeable) and barrels not over 18" (without being removeable).