I have a nice Jeffery .333 double rifle that is just about the nicest little pig rifle you could ever ask for. I have bought custom .333 ammunition fron Stars and Stripes http://www.starsandstripesammo.com The fees are reasonable and they will work with you to achieve anything you want the round to do, ie regulation of a double. Don't know about the Canadian border thing though as they are in Florida.

Bob