Actually....
"Prohibited device" is not the same as a" Prohibited Firearm".
The criminal codes clearly define "Prohibited Device", "prohibited firearms" and "prohibit weapon" differently. They mean different things.
This is a prohibited device
1. Any electrical or mechanical device that is designed or adapted to operate the trigger mechanism of a semi-automatic firearm for the purpose of causing the firearm to discharge cartridges in rapid succession.
What this clause refers to are the lightning link and Drop in Automatic Sear (DIAS). Factory full auto hammer, selector switch and disconnector are
not designed or adapted to operate the trigger mechanism of a
semi automatic firearm. DIAS and LL are designed to make semi automatic AR15 to go full automatic. As a matter of fact, LL will not work will full automatic BGC and DIAS cannot fit into real full automatic lower.
However, if you drill a hole and mill out the lower shelf so that you can put an automatic sear into a semi receiver, then you have just created a full automatic firearm per definition of "prohibited firearms 1(c)
“prohibited device” means
(a) any component or part of a weapon, or any accessory for use with a weapon, that is prescribed to be a prohibited device,
A full automatic firearm is a "prohibited firearms". It is not a "prohibited device". Therefore, only the receiver of a FA firearms is prohibited. You can have AK mags, AK stock... it does not matter. This is because AK is a "prohibited firearm", not a "prohibited device" and therefore it is not under the jurisdiction of the definition of "prohibited device.
However, components or partd of a Lightning Link or DIAS are prohibited devices. This is because DIAS and LL are "prohibited devices" on their own.
In my humble non-lawyer opinion that you should read with a grain of salt for your own entertainment purpose and by no means should take this as legal advice. , you can have all the FA parts your want, as long as your receiver cannot accept these parts to go full automatic, or even if it can accept these parts, it cannot go full automatic. If you modify your receive to take these parts, by simply taking a file to remove 0.05mm of materials, you could be in a lot of legal problems.
Personally, I will not bother. It is not like it is a cool thing to do to put a FA selector in your AR. No one can tell, it does not do anything and why deal with the potential headaches due to misunderstanding?