The part of the gun that is restricted is the part that has the serial number on it (on the real firearm). For most guns, this is the lower reciever which usually include the magwell.. so even if you get all the other parts in, it will do you no good.
Let me point out something else: Airsoft in Canada has been around for a long time. Don't you think if there was an easy (and legal) way to get black airsoft guns into the country we would have found it by now?
ASC, as a community, does not support the aquisition of airsoft guns by minors. You won't find much help here on how to get one.
Yes, people have succeeded in brining them across the border. If you get one in the US, declare it and maybe (5% chance) customs will let you keep it. If you don't declare it, that's smuggling, which is a criminal offence. That means serious fines and/or jail time not to mention a criminal record that will seriously fuck you for life. Don't expect a smuggling charge to magically dissapear when you turn 18. With a record like that, good luck ever getting into the United States ever again.
With that in mind, decide if it's worth it to you to try it -or just do what everyone else does and wait until you are 18.
"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."