No. It's a bit of a tricky question. If the part forms part of a completed firearm, of course, in that sense you're in possession of the part, but this targets when the part is apart from the firearm, by itself. That's the sense in which immunity is required when it stands alone.
As a point of clarification, there is the Preclearance Act, and pre-clearance officer is defined in section 5 of that act. The section in the Criminal Code that this motion amends expressly refers to that section of that act, so the definition of pre-clearance officer is important.