Hello gentleman I have a question I was hoping some of you may answer. I am looking to buy a stripped lower reciever for an ar15 tomorrow, and I was wondering about the paperwork. Being as a stripped lower can technically be built into a pistol, do you have to provide proof of residence along with a handgun safety certificate? I live in Ca. so I already know about the legality towards building it in compliance with state laws. Screw the bullet button.