Also, Special Bulletin #72 is still the standard for use of a magazine in a firearm other that what it was designed for. This is, as mentioned, contradictory to the new "dual use" term which our friend Mr. Smith has come up with which requires the .50 Beowulf mags to be blocked to 5rds of 5.56. Even though there is no actual law, CBSA will not allow them to be imported unless they are blocked to 5.56. This includes the Poly80 Beowulf mags which are in fact designed to feed only .50 BW ammo.
To say that it is all ridiculous would be a major understatement, but it is the world we live in... for now... simple solution... Vote!!