As long as it's a virgin receiver (ie never built into a rifle) and the 4473 is checked "pistol" when you pick up the bare reciever I believe it's OK.*
That's how some of the AR pistols and Krinkov AOW/pistols are being built.
*I am not a lawyer, I don't play one on TV nor did I stay at a Holiday Inn Express last night. This is simply my understanding from having discussed the matter with gunsmiths over the internet who do these builds. As always check with your local (or even better get it in writing from the Technical Branch of the BATF(E)) to avoid any visitations by Bubba the cellmate in the middle of the night.**
**That should be enough CYA for anyone!
