Further, regulating the sale of weapons is different than the right to possess something. There's a good reason why the FEDERAL statutes are almost always restrictions on transfer rather than possession. Heller strikes down arcane laws on what you have to do to legally possess a gun in DC.
It's still near impossible to legally purchase a gun in DC. Rock Island, while only being currently binding in the district it was decided in, gives an insight into the judicial thinking on the FOPA restrictions you are talking about.

