On the ATF site you can find a link to the laws. The laws are often much simpler than recommended practices. For example, the recommended practice is to obtain a signed copy of a dealer's FFL as verification he has one before you ship a gun. The law doesn't specify that you need to verify he has an FFL. The law simply states you must ship to an FFL. If you believe Remington, Winchester, Briley, or Joe Bag-o-donuts gunsmith has one, you can send it. The only thing required by law is that you indeed ship it to a FFL. If it turns out Winchester doesn't have one, you violated the law. If Joe the gunsmith tells you on the phone he has a FFL, and you send it, you didn't violate any law as long as he actually does have one.
