A number of years ago I sold a gun that was eventually used in a shooting. Under Illinois law we're required to keep a record of a gun sale for 10 years. When a couple of LEO's showed up at my house asking about the gun I was able to produce the record, including the buyer's name and address. They were polite and professional, thanked me and told me I was in no way responsible. I wonder how this would have turned out had I not had a written record of the sale. My point is not to defend Illinois gun laws, which are draconian but that I will never sell a gun without a written record of that sale including the buyer's name and address, even if I'm living in a state where it's not required. I understand people's objection to this, but weigh that against protecting myself. If they don't want to provide it I understand with no hard feelings but I won't sell them the gun. It's a good idea to make sure you're covered in case a gun you sell winds up being used in a crime.