As for the rest of the world, many European countries consider the firearm cut off date to be 1870 so be careful what you wish for.
As to why the prescribed calibres? In general the firearms act was written by clueless bureaucrats. Very likely in their minds there were almost no old firearms in other than the listed calibres. Note how they are mostly common US calibres? The anti gun groups in Canada just copy what the anti's in the US say. That is why 25 and 32 calibre handguns are prohibited here. So they have the US firearm "experts" tell them something, they repeat it in Canadian legislation and are happy with the result because Canadian gun owners get screwed.
As to why the prescribed calibres? In general the firearms act was written by clueless bureaucrats. Very likely in their minds there were almost no old firearms in other than the listed calibres. Note how they are mostly common US calibres? The anti gun groups in Canada just copy what the anti's in the US say. That is why 25 and 32 calibre handguns are prohibited here. So they have the US firearm "experts" tell them something, they repeat it in Canadian legislation and are happy with the result because Canadian gun owners get screwed.


















































