I’d suspect that not only would the resident of the state where the trust exists would not only need to be documented as a member of the trust, but also he listed as a responsible party to the ATF when submitting paperwork for the tax stamp. Which would include fingerprints and photos and background check.
I’d suspect the FFL might not be willing to transfer the item unless the person is both a resident of the state where the transfer occurs and the transferee is listed as a responsible party on the NFA paperwork.
Regarding the trust or LLC itself, I think people here have it backwards. In my experience it doesn’t matter what state the trust or LLC was founded, it only matters that the transferee is a resident of that state where the transfer occurs. In other words, you could take an LLC from NY to Florida and have the LLC buy a silencer in FL as long as the responsible party is a member of the NY LLC and a legal resident of Florida.
There’s no reason a NY-based LLC shouldn’t be able to own real property in other states. Even if that property is illegal in the home state of NY. It might be a state-specific Requirement to register the NY LLC as a foreign corporation doing business in FL, however most states would only impose this requirement if the LLC is actually transacting business because they want to tax the business activity occurring in their state. If the NY LLC owns a silencer in Florida in storage of a Florida resident who is a member of the LLC then Florida doesn’t give two shits because no commerce is being transacted in Florida.
The states most likely to be aggressive about demanding foreign LLC filings are also the same states that ban NFA guns, like California. Where if you tried this in California, the FTB would demand the NY LLC register as a foreign entity, pay $1k a year filing fee, even if all you’re doing is possessing a silencer in California and not transacting business. In general, it’s a good idea to avoid the state of California at all costs for any reason.
In sum, all that I’ve experienced matters is the state of residence of the transferee and not of the entity. Whether my experience was shady or a violation of the NFA, I don’t know, I’m not a lawyer.