The enthusiast acts at his peril
The other biased Washington paper notes the arbitrary nature of ATF letter rulings for determining the lawfulness guns:
The Bureau of Alcohol, Tobacco, Firearms and Explosives is in charge of determining whether a gun model is legal, but the agency won’t say much about its criteria.
Despite overseeing an industry that includes machine guns and other deadly weapons, ATF regulations for the manufacture of weapons are often unclear, leading to reliance on a secretive system by which firearms manufacturers can submit proposed weapons for testing and find out one at a time whether they comply with the law, critics say.
The ATF recommends that manufacturers voluntarily submit weapons for case-by-case determination. But those judgments are private and, it turns out, sometimes contradictory. Critics say nearly identical prototypes can be approved for one manufacturer but denied for another.
There’s no set procedure, it doesn’t seem. Sometimes, they approve things then promptly change their mind. Or approve one thing and not another near identical thing. And:
Robert E. Sanders, an ATF official for 24 years who is now a North Carolina lawyer specializing in firearms matters, said letter rulings are often “definitely contradictory and inconsistent,” but are necessary because the regulations being applied are ill-defined.
And these letters don’t serve as much of a defense, should they change their mind.
And good to see firearms regulation expert Len Savage cited.
