No Sir. You are incorrect. It transfers as other. It even says "receivers" next to others.
Scroll down and read the instructions for filling out block 18.
I didn't read the whole thread but a virgin receiver does transfer as other. It doesn't become a pistol or rifle until it is assembled into something. Receivers also don't count as firearms if they are never assembled when paying excise taxes either. As a manufacturer we are required to pay an excise tax if we manufacture 50 firearms in a year. Bare receivers don't count towards that as they are "other".
Ahh, that actually makes sense... not something I'm used to seeing on an ATF form.