Also I have read that if Americans want to bring certain types of guns into Canada, it can be easy.
I heard a hunting riffle can be brought into Canada, if you declare it, fill out a form and pay 35 dollars. Bringing in an uzi would be a problem though and there are no conceal carry permits in Canada.
Canada is not as strict as the UK or Japan, when it comes to guns, there is a stigma around hand guns, but not hunting riffles, for the most part.
I think the terrorist attack in Ottawa back in 2014 would be worse, if the offender got a hold of something more powerful then an hunting riffle.
However there is no constitutional right to bear arms in Canada:
Is gun ownership a legal right in Canada? - Politics - CBC News
But messing with hunting riffles can be costly politically:
The rise and fall of Canada's long-gun registry - CBC News - Latest Canada, World, Entertainment and Business News