Pretty much the entirety of the National Firearms Act as projected through Miller.

I fully understand the social context of the time, (shortly having come to pass after the events of the Valentine's day massacre) but find the entire logic behind it flawed, and open to challenge on the grounds it's essentially a poll tax (unreasonable barrier to entry on the exercise of a constitutionally guaranteed right) predicated on the Federal power of taxation of interstate commerce, which is it's own bag of shakyness.

I was reluctant to even post it because it almost always devolves into a whining match that no one is infringing anything, until you add the "closing" of the Machine gun registry in '86 into the picture where the registration requirement creates a de facto ban on civilian ownership/production of automatic firearms for lawful purposes because Congress has mandated no money be spent updating or maintaining the registry; leaving it open yet non-functional, constraining supply of legally transferable automatic weapons to those produced and registered prior to 1986. That notwithstanding there's a lot that has been hung on the coat rack of that entire vein of politicking that just smells to high heaven to me.

But we aren't talking about that, we're talking about Miller, being the one case in which the Supreme Court leaned so heavily on a qualification that an arm must be kept and used consistent to the prefatory clause of the Second Amendment, thus cementing the next 50 odd years of slow methodical encroachment on firearm owner's rights to keep and bear arms until Heller reversed the stance, and explicitly acknowledged the non-modificatory nature of the prefatory clause on the operative clause of the United State's 2nd Amendment.

Note I'm not opposed to some level of tracking/registration of certain firearms in general; just not combined with the wild gesticulations that have been employed to create de facto bans and excessively high barriers to entry to possessing, fabricating, or doing business in firearms. To me, the 'keep' part of the 2nd Amendment covers the right to fabricate replacement parts as needed, even receivers, but in the eyes of the Law, the act of fabricating or production is separate from the Act of keeping (possessing). Hence to meet with my standards of keeping, you not only have to pay a $200 tax, you have to pay an appropriate recurring SOT ($2000ish last I checked), which also requires you to essentially do business as an FFL of some flavor, and to structure your life around what should be as frictionless and routine an interaction as humanly possible because otherwise the Federal government will unilaterally decide you don't really need that right to "keep" (to my standard remember) those arms because you're not engaging in enough interstate (or intra-state commerce due to some effing grain taxing case that SCOTUS ruled on that established the interstate commerce clause granted Federal regulatory authority on intrastate commerce if that stuff had a reasonable chance of effecting the interstate market environment) for it to be a slam dunk case that Federal Law Enforcement can dunk on you for effecting or attempting tax evasion in violation under jurisdiction granted by the interstate commerce clause, which is really being employed as a workaround to clamp down the number of automatics or undesirable firearms, and disenfranchise any poor sod who doesn't sweat the details enough of their right to vote via a felony firearm charge.

I've spent entirely too much time thinking on this sort of thing. Especially since I only own a Mossberg, but it's the principle of the thing. I downright object to any implementation of something that requires an average person to navigate that many layers of indirection for something that should just be straightforward.