I can't imagine there is another country stupid or foolish enough to allow folks armed in military gear to assemble in public.
Maybe it's time to re-write the 2nd A to state that Americans have the right to a handgun for self-defense or a rifle for hunting, but that military weaponry such as assault rifles, automatic and semi-automatic weapons are not permitted. And States are permitted to regulate the licensing and public display of legal weapons.
The Right would get the SCOTUS ruling in the Constitution so gun ownership would be a settled right, but heavy weaponry would be banned and states could regulate/limit public carry as they see fit.