I recall reading something from the CBC like you posted on a firearms forum. Along with the CBC article was other stats confirming (in my eyes) that CBC is mis representing the facts.
I recall reading that the handguns that were orginally purchased leglly, but then landed in the hands on criminals were actually in fact mostly stolen from the legal owner. Yes a few were legally bought and then illegally sold.
I honestly have a hard time swallowing that any legal hand gun owner in Canada would even try to sell a handgun illegally. It's insanely controlled here that if that gun is used in a crime it WILL be traced back to you. Of course you can grind the main serial number off or report it stolen after you sell it, but unless your going to do this with say 20 hand guns, it won't be worth your time for several reasons. 1) If you report a handgun as stolen, expect to prove that it was stored properly. Its pretty hard to steal a hand gun if stored properly. The thief would need to either remove a large safe from a house or grind/cut through the safe. Odds are if your handgun is stolen you have a good chance of being charged for improper storage and loose all your guns and your liscence to buy them. 2) By having a lisence to buy handguns, you are automatically getting a microsope on your purchases. So if you decide to buy 20 hand guns for the purposes of illegally selling them your home has a good chance of being inspected by the firearms officer in your area/rcmp.
Its so tightly controlled here (handguns) that once your in the know about the laws surronding them you can see how absurb it would be to have someone selling a bunch illegally.
The USA does not keep track of handgun owners nor keep track of the serial numbers of the guns that you buy. It's been proven their laws are easily abused to benefit people with bad intentions.
I should add, I'm very open to stricter laws (that are reasonable and make sense) about proper firearm storage. One law might be, if you own handguns you must have a alarm of sorts. I'm just thinking out loud.