This might provide an informative article for many to read, and reference to many of the repeated questions asked here. Got it in an e-mail from the BATF today.
ATF's Top 10 Frequently Asked Firearms Questions and Answers
http://www.atf.gov/firearms/industry/0501-firearms-top-10-qas.pdf
ATF's Top 10 Frequently Asked Firearms Questions and Answers
http://www.atf.gov/firearms/industry/0501-firearms-top-10-qas.pdf