Here...this is from a recent case in Ontario involving the Superior Court of Ontario and the CBSA:
"16. The CBSA submitted that the rifles in issue are not firearms, since the projectiles that they discharge are unlikely to cause serious bodily injury or death to a person, as required by the definition of “firearm” pursuant to section 2 of the Criminal Code.
The Tribunal agrees with the CBSA that, to be considered a firearm, an airsoft rifle must have a muzzle velocity that exceeds 124 metres (407 feet) per second. Because the rifles in issue have muzzle velocities that are below this threshold, the Tribunal agrees with the CBSA that they are not firearms. Based on the definition of “firearm” found in section 2, the Tribunal is satisfied that the second condition of the definition of “replica firearm” is fulfilled, i.e. each rifle in issue itself is not a firearm.
The way i read it is that if the "airsoft" gun shoots over 124 meters (407 feet) per second, it is therefore a firearm. Now...this is ware it gets neat....a pellet gun or BB gun fires above 407 yet below 499...and therefore does not have to be registered with the RCMP, ie PAL...i know this because i called them and asked!!!
So, you get a (Maruzen MP5) that shoots over 407FPS yet under 499FPS...you now have in essence a firearm that falls into the airgun/firearm and not replica/airsoft category that you do not need a license for nor will the CBSA have anything to say about it when it comes into Canada.
Oh wait, was she a great big fat person?