Antique would be defined by Canada and that is defined as 'no PAL required'. It is established mainly on the availability of ammunition for said firearm. If the ammunition is obsolete then often the gun is considered antique. You might want to check the RCMP as I believe there may be a list of antique guns. No breech loading Sxs in regular guage regardless of age is considered an antique

Nothing is foolproof to a sufficiently talented fool.