I was also surprised to learn that as of 1 Sept 2024 you also need a PAL to buy a firearm barrel or handgun slide.
So you're saying you never read c21 when it passed in Dec 2023? Because it's in there, plain as day:
21.2 The Act is amended by adding the following after section 25:
Authorization to transfer firearm parts
25.1 (1) A person may transfer a firearm part to an individual only if the individual holds a licence authorizing them to possess firearms.
Firearm part is also defined in c21:
(5) Subsection 84(1) of the Act is amended by adding the following in alphabetical order:
firearm part means a barrel for a firearm, a slide for a handgun and any other prescribed part, but does not include, unless otherwise prescribed, a barrel for a firearm or a slide for a handgun if that barrel or slide is designed exclusively for use on a firearm that is deemed under subsection 84(3) not to be a firearm; (pièce d’arme à feu)