As at least 3 people have said; Contact BATF NFA Branch to find out if it is in the registry before you take a chop saw to anything. If so, you or your aunt may be eligible for a tax free transfer on a fairly valuable weapon. If it is in the registry contact an experienced, trusted dealer to help you through.
If it’s not in the registry then there is no way for you to turn the lower into non-contraband. If you know anyone in LE then you may consider having it run for stolen… Or, you could take a chop saw to the lower receiver.
Just realize that if not in the registry then the receiver is contraband. Don’t take possession of it, and don’t just leave it in your aunts attic as a trap for some other family member. If it proves to be contraband destroy it.
ETA here is some stuff from the NFA handbook that may be useful to you.
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.
9.5.3.5 Distribution of decedents’ “sales samples.” If NFA firearms in a decedent’s estate are
“sales samples,” that is, they were imported and distributed to the decedent as sales samples or
were domestically manufactured machineguns distributed to the decedent as sales samples, the
sale sample restriction continues in effect and lawful possession of the firearms requires that the
firearms be held as “sales samples” for demonstration to government agencies.171 Therefore,
these firearms within an estate must be transferred to government agencies or FFLs/SOTs as
sales samples for demonstration to such agencies.
9.5.3 Distribution of estate firearms. A decedent’s registered NFA firearms may be conveyed taxexempt
to lawful heirs. These distributions are not treated as voluntary “transfers” under the NFA.
Rather, they are considered to be involuntary “transfers by operation of law.” Under this concept, ATF
will honor State court decisions relative to the ownership and right to possess NFA firearms. So, when
State courts authorize the distribution of estate firearms to decedents’ lawful heirs, ATF will approve the
distribution and registration to the heirs if the transactions are otherwise lawful. A lawful heir is anyone
named in the decedent’s will or, in the absence of a will, anyone entitled to inherit under the laws of the
State in which the decedent last resided.
9.5.3.1 Distributions to heirs. Although these distributions are not treated as “transfers” for
purposes of the NFA, Form 5 must be filed by an executor or administrator to register a firearm
to a lawful heir and the form must be approved by ATF prior to distribution to the heir. The
form should be filed as soon as possible. However, ATF will allow a reasonable time to arrange
for the transfer. This generally should be done before probate is closed. When a firearm is being
transferred to an individual heir, his or her fingerprints on FBI Forms FD-258 must accompany
the transfer application. The application will be denied if the heir’s receipt or possession of the
firearm would violate Federal, State, or local law. The law enforcement certification on the form
need not be completed. The form should also be accompanied by documentation showing the
executor’s or administrator’s authority to distribute the firearm as well as the heir’s entitlement
to the firearm. Distributions to heirs should not be made until Forms 5 are approved. Executors
and administrators are not required to have estate firearms registered to them prior to distribution
to lawful heirs.
9.5.3.2 Distributions to persons outside the estate. Distributions of NFA firearms by
executors or administrators to persons outside the estate (not beneficiaries) are “transfers” under
the NFA and require an ATF-approved transfer form. Transfers of serviceable firearms to other
entities or persons require an approved Form 4. Form 4 applications must be accompanied by
the applicable transfer tax, and, if the transferee is an individual, the transferee’s fingerprints on
FBI Forms FD-258. Applications will be denied if transferees’ receipt or possession of the
firearms would violate Federal, State, or local law. Also, Form 4 applications to transfer
firearms to individuals must contain the law enforcement certification of an appropriate law
enforcement official. See Section 9.8 for further information on these certifications. Form 4
applications to transfer firearms to non-FFLs residing outside the State in which the estate is
being administered will be denied. Form 4 transfers should not be made until the transfers are
approved.
