regarding export of ammo from US to Canada: Canadian law allows for import of a significant quantity without a permit, but the US requires an export permit. As Tamid experienced, unlikely that Canadian Customs would be concerned about the US export permit being in order. The chance of getting checked by US customs on departure is clearly very low, but departure checks do occur and I would imagine that the potential consequences could be extremely unpleasant.

If on a hunting trip I wouldn't think a small quantity left over would attract any attention coming back.

Would be great if someone picked up distribution of RST in Canada, but on the other hand with the current exchange rate it would make for pricy shooting. I recently bought a 2 1/2" gun and after looking at the limited options in Canada, decided to try my hand at reloading.