There are A-- holes that work in every occupation. In fact being A-- holes is their life's goal. It's too bad.
You know, for a Canadian wanting to buy a gun from the US,it might not be that big of a hassel if the seller in the US had a PAL. The seller would have to come into Canada with the gun, say on a hunting trip. If you look at the Canadian firearm's regulations, it says an American who has the Canadian firearm's licence can sell a gun to a Canadian once on Canadian soil if the Canadian also has a PAL. I guess they figure the American that has a PAL has already been checked and has met Canadian requirements so once in Canada it is treated as any other Canadian firearms transaction. This is talking for sale of a "used gun" between private individuals.
On the subject of gun parts, I have bought parts a few times for some of my vintage Mossberg .22's from Numrich and they were sent through the mail with no problem. Parts that are not restricted of course. I don't believe a shotgun barrel is considered restricted.