There is a lot of less than accurate information there. I have sold my share of firearms and once the bill of sale was signed the gun is the purchasers and their responsibility. I will Give that states have their own laws concerning the sell and it may vary.

The scenario you described would be better solved with a free and open Background Check system everyone hav access to to verify the status in private sales

I'm all for universal background checks but I think "free and open" might be hard to do. It sounds like a private company, GSE or government agency would need to maintain a database in order to make this work. Once again... a registry is born.

The best way to solve our "gun" issue because we DO have one in the USA is to simply require all sales between any two parties go through an FFL. Put the penalty on the current owner if this law is broken. 2A provides a right to "keep and bear" not to sell, give away etc.