In 1787 private armies were not uncommon.
I’ve never understood the rational that the 2nd amendment only covers the things available in 1787. A firearm still operates on the same principle as it did in 1787. Combustible material ignited in a confined space ejecting a projectile out of a single orifice, where the outside diameter of the projectile is only nominally smaller than the inside diameter of the orifice.
the other capacities, such as repeating, semi-automatic, and fully automatic are mechanical systems, external to the initial thermo-mechanics.
True, the only difference between my flintlock and 1911 is the ignition system.