Nope.
Not unless the shooter was a criminal and was denied a Possession and Acquisition Licence (PAL). Otherwise, if he took the course and had no domestic violence suspicion, he would likely be approved for a PAL.
I read that an older bolt-action .30 caliber hunting rifle was found. This is about as mainstream medium-big game (deer moose, bear) classic hunting rifle as there is.
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There is no way this class of rifle can be banned in Canada unless we outlaw hunting, including sustenance hunting.
.30 calibre is the bullet diameter, but the cartridges that shoot .30 cal bullets can range from the John Wayne cowboy 30-30 lever action to 300 Winchester Magnum or even 300 Remington Ultra Magnum. Police snipers genreally use 300 Winmag. Some military snipers use the 300 PRC if they aren't shooting .50 BMG. IIRC .50 BMG is now illegal in Canada.
The AR-15 / AK style 'assault rifles' also shoot .30 cal called a 7.62mm NATO which is roughly equivalent to (
but actually less powerful) the most common hunting round, the .308 Winchester. (AR-15 style also comes in a lighter round called 5.56mm NATO which is (vitrually) the same as the civilian Remington 223 . Another of the most common general duty medium game (coyotes, wolves even woodchucks/groundhogs etc)
And if the gun and ammo were securely (and separately) stored by the owner, (say the parent or grandpa etc) as required by Canadian law, then the kid shouldn't be able to access it.