Rumors are that they want to categorize “pistol” that can fire a rifle round into the “AOW” category of the NFA of 34 requiring federal tax stamp and registration.
I can see them trying that approach - plus other things they attempted in the past, like reclassifying M855 'green tip' as armor piercing, etc., etc., etc. Obviously, they won't feel any need to be bound by facts, previous determinations, or even judicial opinions (now that the high court is running scared of the Dems packing threat)...