Legalities aside, the real point in case is that the manufacturing of goods gets sent abroad.
Even if you had a potential market for a million units, you won't find labour in Canada that can compete with the price of labour in China. Unless you're offering something no one else is offering, people will go for the better deal. Even if you are offering something of superior quality (such as CNC machined parts) the higher cost will erode your market base.
So your market is pretty much only Canadian, and that would assume parts and guns couldn't be imported at all, which isn't currently the case.