Just a slight point of contention: The rules state that an entity can retain pre may samples, so long as the entity remains alive. Here is the reference: (and I am posting this for your benefit) So entities and sole props can retain pre may guns and other NFA items.
14.2.2 Corporations, partnerships, and associations. FFLs licensed as corporations, partnerships, or associations, who have been qualified to deal in NFA firearms and who go out of the NFA business, may lawfully retain their inventory of these firearms, including imported NFA “sales samples,” as long as the entity does not dissolve but continues to exist under State law. No NFA transfer occurs that would require an ATF-approved transfer because the firearms are still possessed by the same entity to which they were previously transferred and registered. However, any firearm registered to the entity as a “sales sample” would continue to bear the “sales sample” restriction on any subsequent transfer, unless the firearm is being transferred to a government agency. Thus, the transfer of a “sales sample” to other than a government agency will only be approved if the transferee is an FFL/SOT qualified such samples.220
