Ammo is limited by weight per person.
Where did you come to this conclusion?
I have found two drastically different limits for ammo being transported, and neither had anything to do with weight. I think for a permanent dwelling in Canada there's a 225 Kilo weight limit of ammo that can be stored but not for transport through Canada by a non-resident. This is what I have found on Canadian government websites:
Your declaration counts as a registration certificate and a license to have your weapon. It will allow
you to buy ammunition in Canada, and to transport up to 200 rounds into the country with you.
Importation, Exportation and Transportation In-Transit of Ammunition
Any individual can import up to 5,000 rounds of small arms cartridges into Canada without an import permit if they are for personal use (i.e., not for resale). If you plan to resell the cartridges or to import more than 5,000 rounds, you need an import permit. Similarly, you can export and transport in-transit up to 5,000 rounds of small arms cartridges for personal use without an export and transport in-transit permit, but you need a permit if you plan to resell the cartridges or to export and transport in-transit more than 5,000 rounds.
To the OP:
When I had my transfer paperwork (US government, but not military) I arrived at customs with 4 rifles and a shotgun, a pre-filled out Form 909 and a Continuation Sheet (RCMP GRC 5590). I paid my $25 Canadian and was on my way. They didn't even look at the guns. Maybe I got lucky, or maybe my government paperwork made them feel easy about me. I don't know but I wish I had brought a lot more rifles and shotguns up now. Since I didn't do that, every time I fly back I plan to bring a few more and some handguns with me in an airline approved rifle case.
I purposefully crossed at a small, rural POE and called them beforehand to get their thoughts on the matter, but didn't ask about ammo. I should have but it's a non-issue now.
