No citation needed, there is no prohibition in Federal law, only State law, and you cherrypicked the most restrictive States in the nation as your exemplars. For example, something like 40+ States permit suppressors. High-explosives was (is? probably with more paperwork now) a retail business in many states; I stopped by one once just to check it out for myself, the only requirement was that I had a vehicle that met road safety requirements for transport e.g. carried on a surface that is not prone to sparking.

I had a couple friends many years ago who, mostly for fun I suspect because they never did anything with it, filled out the relatively simple Federal paperwork that gave them carte blanche to import/manufacture/buy just about any conventional weapon you can think of and they lived in a State with no restrictions. But almost no one does in practice because once you go beyond what is possible to fabricate in a sophisticated machine shop, it would become an extremely expensive hobby for no obvious purpose. Few people can afford to drop millions of dollars on guided missiles.