As a northern neighbor to the most armed country on the planet, let me chime in.
The 2nd amendment is outdated and since amendments can be amended

it should include an annex that forbids the possession of weapons in common spaces, I have no problem with people owning bazookas to defend their property, to protect family against governmental tyranny at home, fine. Your armed citizens aren't stopping F..All in gun crimes, no reason Granma dynamite to be carrying oozies Yo!
The only citizens that should be permitted to carry weapons in common areas(public) are police officers, private security guards, military folks, firemen and maybe a few other choice civil servants. You'd be shocked at how many of these people exist in the US, all having strict firearms training and quarterly psychological assessments.
Vote for me and nobody gets hurt
Well Justin Trudeau's cuz
The problem with your thinking is, criminals have guns, the mentally unstable have guns.
Gun free zones invite all sorts of unsavoury characters, what the media hasnt told you is the areas with the most gun crime violence are low income areas where gangs thrive.
Just like I used to read about the Mafia in your province particularly Montreal had mafia gang shootings including a boss if I'm not mistaken, you have bike gang turf wars, but this gang stuff doesn't happen much in Quebec city? but we generally know your country is safe.
Mass shooting is a small percentage compared to the gun deaths from hand guns from criminals and the drug trade.
that is something the media wont point out.
How likely is it that someone will commit a gun crime if they know everyone is carrying a gun?
Can't recall if it was Naked Gun or Loaded Weapon that showed this action.
While it was funny, it was also pretty accurate.
There will still be insane people attempting mass killings but anyone, even a criminal in their right mind is going to think twice before pulling a gun where he could be shot from any angle immediately.
It may not be a viable, practical solution but it would be effective in diminishing gun related crimes.
The great threat of guns is that only few of many have them. Reducing the number of people that have them, increases the threat because the few will still be able to find them.
The only way to eliminate the threat is to destroy all guns everywhere so nobody can ever possess one. Then the problem will turn to something else as the threat. There is no possible way to control every single gun that exists. There is no way to control every mind that might possess a gun.
We can make an attempt to control gun ownership but that is merely a stop=gap exercise that hides the real problem. People do crazy things.