"Nice set of pistols....time to file some Form1's!
According to the ATF agents I talked to on the phone (I wore them out with questions), a Form 1 is not required to build a pistol. I think that's for a SBR, or suppressor. Both the recievers were purchased new, by me, and have never been rifles. They were marked as "other, reciever" on the background sheet.
It was explained to me, by the ATF agents, that it was not necassary to register them, as it is legal for an individual to manufacture a firearm for themselves, so long as it is not being built with the intention of resale. They started out life as pistols, via me.
Anybody feel free to chime in if I'm wrong!!!!