I have an old mauser with a very good set of open sites that I would like to keep. The bore is so-so and I was considering having it re-bored and chambered to a 35 Whelan. There are a couple smiths in Canada that re-bore barrels but they are so busy this project will take forever. There are quite a number of shops in the US that re-bore and I'm told their turn-around time is about 3 months. Anyone out there know the legal end of this ? Can I ship a barreled action to a gunsmith in the US for work? Do I need a permit from the Bureau of AT&F ? or from the Firearms centre ? Anyone else done this?