It's not the parts, necessarily. What this amendment does is provide a transitional provision for illegally manufactured firearms.
If someone, for example, manufactured an illegal firearm prior to the coming into force of this provision, it could be non-restricted, restricted or prohibited. Following the coming into force of this bill, if passed, the firearm would be a prohibited firearm. In any proceedings after the coming into force, that firearm would be prohibited and therefore subject to higher penalties.