this would be a pretty big change for those that have bought finished but bare lowers and did not register them in MAI'm not saying that it needs to be registered, just that AG & DAs may consider it one for prosecution. Paging @Rob Boudrie as he tracks the case law and I recall him mentioning a case where the judge ruled that if all it took was replacing parts, it's a functional gun as far as the Marsupials are concerned. Rob can fill in detail as I don't track case law (with minor exceptions).