It's good to see that gun registration works so well.
No amount of gun registration would've stopped this incident... the Concordia University shootings and the Ecole Polytechnique slayings were also done with registered and legal guns.
Registration does two things though.
1) Gives the Police a head's up that a house that they're going to has weapons in it, and what type. Not all the info, because it doesn't cover illegal weapons, but better than nothing.
2) It slows down those who get angry and go to a store to buy a gun. In addition, people can get refused licensing and guns.
Overall...it doesn't stop all whackjobs from getting guns...but if it stops half or more...that's a good start, eh