Rell, I'm sorry to hear of your loss. I would suggest you get photos and descriptions out to contacts in the U.S. In the U.S. we have a program called N.C.I.C. (national crime information center). Stolen property is listed by serial number and description there. Canada has a similar program, however if an item is queried in the U.S. NCIC it will not automaticly querie Canada. It has to be queried seperately and is unlikely to occur, unless there was some reason to believe it was stolen from Canada. It would seem that anyone trying to sell your gun would likely take it to the US. You may want to speak with the investigating officer about having it listed NCIC if possible.
good luck