No...you aren't wrong. The lowers legally do not need to be registered on FA-10 til they are built into a firearm. Many have non registered pre-7/20/16 lowers, the only proof you need lies in the federal form you transferred it in on. Many of the dealers that did these transfers are out of business, and many people did not keep a simple register slip from years ago, where they saw nothing like this coming. I'll also contend that many slips might have been just for a transfer fee and nothing else, as the receiver may have been bought online. So really....you have a receipt for a transfer fee, with nothing else on it, what does that prove? Sure, had we seen this coming maybe all the name and numbers might have gotten put on the slip....a lot of times they didn't. The state would have to look up the federal records to prove you transferred it in after 7/20/16 to do anything to you about it. In 99% of the cases, that would conclude that most people transferred them in before 7/20/16 and they are Healy legal. They would essentially prove they have absolutely no case against you. Not to mention the fact that there is no actual LAW backing up the pre 7/20/16 thing. I'm not sure which LAW they would charge you with breaking in the first place. Part of my point here is, that anyone can scratch together a sales receipt.....it alone means crap. The federal paperwork would be the proof positive in any and all cases against someone.