Correct. NFA items owned by individuals transfer tax-free on an ATF Form 5 to your lawful heir.
http://www.atf.gov/press/releases/1999/09/090599-openletter-nfa-estate-transfers.html
Sh*t. Learn something new everyday. Still do a trust to allow my wife or other beneficiary to use the items and have access to the safe (Right now two of the guns that her dad left her when he passed are woth more than all of mine.).