The American republic was fatally flawed ab ovo, to be sure, but it was not a “nation-state” of the kind brought into existence by murderous centralizers like Bismarck, Lenin, and Lincoln.
The Second Amendment is actually a much worthier document than the Constitution itself. That Amendment served two indispensable purposes. One was to forbid (in concept, if not in execution) the federal government from disarming the state militias, which would (and did) lead to a deadly concentration of power. The second, and more important, purpose of that amendment was to recognize, unambiguously, the individual right to armed self-defense.
That right exists independent of government, and cannot be infringed by it.