Depends on how much you are buying as well, as to what hoops the US vendor needs to jump thru. Graf's and Brownells for sure will ship to Canada, and there is a Low Value Shipment limit of 500.00 that the old version of permit isn't needed for, but, they did/do have to buy export licences to be able to qualify for that. And those two at least have people on staff or retainer ( like a licenced brokerage) who have been trained for export. 98% of Americans have no clue about their own export laws, other than it's too much trouble for the smaller stores to be bothered with, or the cost/time factor is more than Cdn business is worth to them.
You can read thru this and then ask someone who comprehends it, like a broker, and, a US one at that, as to what is what. I believe, pg 12, 13, 23, 27 are where you need to look, and wherever/ whatever they relate to. Reading a bit of it may tell you why most US vendors can't be bothered with it. I know I don't have enough understanding of some of the legalese to decide for myself on it.
Cdn import regs have zero to do with this stuff other than supplying import/end user paperwork for the over 500.00 shipments, and certain items that don't qualify for LVS. No idea what other updates there are to this document.
https://www.bis.doc.gov/index.php/do...te-7-7-20/file