They don't, and it isn't. But that 20 rounder can be shipped to many other countries. Brownells does not have a Canada specific section and there are items not listed in the "available outside USA" that can be exported to canada due to our special relationship. They will not pin mags but there are various states with mag restrictions that sometimes work in our favor.
The main restriction to watch out for on each individual product listing it a line in the description saying the item cannot be shipped outside the USA.
They expect you to figure out what is legal for you to purchase and import before purchasing.
