Keep automatic weapons legal, however require the ATF to stamp automatic weapon boxes that are bulletproof and use either: a biometric lock such as eye(retinal)/ fingerprint, OR a certain level physical combination lock (1000's, millions of combinations), OR a new USB lock that could contain a digital key and RFID chip to double unlock (and the digital key keeps changing on a key fob such as a SecurID with a RFID chip also), OR a combination of any of the three options of locks.
Please see: http://en.wikipedia.org/wiki/SecurID for more information.