The countries that have tried it gave up, the cost vs gain was an easy excuse, the reality is they lost control, about half the people did not comply. In US terms over 150 million new felons, plus the costs to build and maintain the records, the buying and selling, taxes, etc. In the end the nation can't pay for health care and the 350 million firearms that are already on the streets haven't harmed anyone. It is a waste of time and resources, we do not need laws so political hacks can pretend they did something. The hard truth is the feds can not control interstate commerce, which is why you have state gun laws, state property etc. Although all 50 states would not sue or make laws against following any illegal federal power grab, many would. Gun registration at the state levels has been there for years, no state shares the data and most never would, nor would dealers. I could also point out no one will ever trust either party to not abuse the system both have already convinced half of us they hate us. I say half because Dems and Reps see their side as righteous and the other as criminals. I see two sides of the same coin and I know many people that would never obey any law passed to record their own property at a federal level. If that meant prison time, I would help hide them without blinking.