https://www.canlii.org/en/bc/bcpc/d...AAAQAYY2FydHJpZGdlIG1hZ2F6aW5lcyBib2R5AAAAAAE
The accused ordered seven magazine casings designed for use in AR 15 variant rifles from a well known U.S. mail order supplier of firearms and parts, Brownell’s Inc. He had the order delivered to his mailing address in Squamish, under his own name, and attended in person to pick it up. When he did so, he was confronted by at least five police officers, and arrested. The police had presumably been alerted by customs or postal officials to the possible illegal importation of firearm magazines, and, of course, they took the matter seriously.
[6] The Crown led evidence from a firearms expert, Cst. Grosspietsch, to establish that as of 1993 all semi-automatic firearms may only possess magazines that hold up to five rounds of ammunition. The casings seized from Cancade had a 30-round capacity and were not “pinned” to prevent their use for more than five rounds, as required by the firearms regulations.
[7] Grosspietsch observed as well that the imported casings did not have an internal spring, bottom plate, or follower plate. These parts would need to be installed in order to make the casings capable of receiving cartridges, and becoming functional. The follower and bottom plate are required to keep cartridges inside the casing; without them, the casing was hollow and cartridges would simply fall out. The spring is necessary to create the compression that feeds cartridges into the receiver. Grosspietsch said the required parts are readily available, and their installation is not particularly difficult.
[8] Grosspietsch agreed that the 30-round magazines were capable of being used in several types of non-automatic firearms that could be legally owned in Canada, and that if pinned, they would not be prohibited.
[34] In any event, I conclude that the magazine shells imported by Mr. Cancade were prohibited devices, being containers from which ammunition may be fed into a firing chamber, and being capable of containing more than five cartridges.
[35] As for the defence submission that Cancade did not intend to possess prohibited devices, I agree as well with the Crown submission that possession of the unaltered device, coupled with an intention to possess it in that form, satisfies the mens rea component of the offence. Ignorance as to whether they are caught by the legislation in their unassembled form is ignorance of the law.
[36] With deference to a thorough and initially attractive argument by able defence counsel, I am nonetheless persuaded by the Crown submissions and the applicable case law that a purposive and reasonable interpretation of the applicable legislation requires convictions on all counts.
I'm sure there are a few more, IIRC there was a similar case in ONT where mag bodies deemed as the prohibited part.
