Collectors source ones were deactivated to some degree. Clive Law, when he was at the DFAIT desk, required the big guns (ie tanks) to have a certain amount of deactivation.
While the firearms act may not have intended to encompass artillery, the RCMP lab has apparently decided to do so. I tried to de-register my 76mm Sherman gun and mantlet last year but they refused, saying it was a barrelled weapon which could cause bodily harm. I'll wait for the conservatives to get rid of the longarms registry, and then see where that takes us.
The Swissicon boforss are very similar, but not the same. The trailer chassis is somewhat modernized to European specs. I think my friend has his firing tennis balls or golfballs or something. For the differenc of 5 or 10 grand, I would want the Cdn one.