What is needed to get a full automatic weapon in the US?

First, have a lot of money- Legal full autos are very expensive. The last LEGAL full auto M16 I saw for sale (transferable to a private citizen) was $16,000. Next, live in a state that permits private ownership of a full auto- some do not. Then locate a Dealer in your home state that has a license to deal in machine guns- commonly called a Class III license. You will need to apply (through the dealer) to the BATFE to transfer the weapon to yourself. You submit the written application, fingerprints, and approval from your local chief law enforcement officer, along with the $200 tax on transfers of a machine gun. You must meet the other legal requirements to own a firearm- age, criminal history, etc.