Found the NFA handbook:
9.5.3.3 Uncertainty about the registration status of decedents’ firearmsIn some cases, an
executor or administrator of an estate may be uncertain whether the decedent’s firearms are
registered to the decedent in the NFRTR. Perhaps the executor or administrator is unable to
locate the decedent’s registration documents. As discussed in Section 9.2, if the decedent’s
firearms are not registered to him/her in the NFRTR, the firearms are contraband and may not be
lawfully possessed or transferred. If the executor or administrator cannot locate the decedent’s
registration documents, he/she should contact the NFA Branch in writing and inquire about the
firearms’ registration status. This inquiry should be accompanied by documents showing the
executor’s or administrator’s authority under State law to represent the decedent and dispose of
the decedent’s firearms. Although ATF is generally prohibited from disclosing tax information,
including the identity of persons to whom NFA firearms are registered, ATF may disclose such
information to persons lawfully representing registrants of NFA firearms.
9.5.3.4 Unregistered estate firearms. Should an estate contain NFA firearms not registered to
the decedent, these firearms are contraband that may not be lawfully possessed or transferred.
Where these are found within an estate, the executor or administrator should contact his/her local
ATF office and arrange for their disposal.
Thank you very much.