Never had a problem with crossing the border. When I asked the border crossing guards (first gun I brought I drove across) they said over 18" and rubber band, no issues. And being the Mako gun I got is more like 40" or whatever they just looked it over, said it was cool, and charged me GST and off I went. The other 2 guns I've had mailed USPS or UPS and both had zero issues coming across.
So, BC or not, you should be good to go!
So, BC or not, you should be good to go!