Updated February 22, 2013
Every existing state bill of rights in 1789 (eight instances) [The Origin of the Second Amendment, pp.747-780], and every proposal of bill of rights related amendments for the Constitution voted on by state ratifying conventions (seven instances) [OSA, pp.151, 260, 446, 459, 481, 505, 735], included a Second Amendment related provision, which was always accompanied with a limit on, or warning that a peacetime standing army was dangerous to liberty. In all cases where a complete bill of rights was involved (thirteen instances), there was a third linked concept closely related to the first two - that military forces were controlled by the "civil power".
These universally present American bill of rights features were first identified in TheFounders' View of the Right to Bear Arms and dubbed Mason Triads, because their earliest iteration appeared in the 1776 Virginia Declaration of Rights written by George Mason. [FVRBA, p.4] Complete Mason Triads always had leading Second Amendment related protection, either well regulated militia of the people, or, the people have a right to bear arms style language. This was universally followed by language discouraging or limiting a standing army, with the final part subordinating government raised force to the civil power. The Mason Triads from the last four state ratifying conventions duplicated the Second Amendment related protection by including both the people have a right to keep and bear arms and the well regulated militia of the people style language as the leading triad part. [A complete listing of Second Amendment predecessor Mason Triads can be found online in Appendices I and II of The American Revolutionary Era Origin of the Second Amendment's Clauses.]
While proponents of gun control have interpreted the Second Amendment, its predecessors, and related language appearing in Mason Triads as all about military matters entirely under government control, the exact opposite is actually the case. The purpose of Mason Triads was clearly "barriers against power in all forms and departments of Government" as James Madison described American bills of rights in 1789. [The Origin of the Second Amendment, p.657] He was introducing the predecessor of the U.S. Bill of Rights into Congress and his proposals, based directly on those barriers, were the foundation of the first eight amendments, including both clauses of the Second Amendment. [OSA. pp.654-661]
Madison and Congress retained the leading Second Amendment related protections from state convention proposed Mason Triads but dropped the final two parts because their restrictions were substantially included in the original Constitution. Funding of armies was limited to two years and required legislative approval, the latter being the limitation specified in four of the original state Mason Triads. Additionally, all military force raised was under the direction of a civilian commander in chief, who was backed up by the power of the entire civil population that had authorized the Constitution, thus making it the supreme law of the land not only on paper, but also in fact. Since numerous period documents presenting Federalist and Antifederalist arms mantras emphasized the people were armed and could prevent tyranny, the only essential Mason Triad part needed as an addition to the Constitution was assurance for existence of an armed populace, which the Second Amendment amply provided. See the previous post, The Second Amendment and Founding Era Arms Mantras, below, for further information.
Placing the Second Amendment into its appropriate Mason Triad period context as a barrier against government power greatly clarifies its meaning. It was never intended to protect state militia authority because its predecessors were understood as barriers to the power of the states. Instead, its purpose was to assure the people's control over the new Federal Government they authorized and any forces it might raise. This information fully explains the Second Amendment's references to a free state and the necessity of an effective militia of the people, who would be able to self-embody for organized defense with their own arms, because their right to possess and use arms was protected against any meddling by the government.
The citizens in 1789 relied on flintlock firearms just as the soldiers of a period army. At that time, a standing army in time of peace was the face of tyranny. Today, the face of tyranny is just as common in the world, but is much more intrusive and dangerous, and is usually referred to as a police state. Americans have the constitutional right and duty to prevent the establishment of any police state in the United States. The people must keep their government under their control, which is accomplished, not by fighting, which is only a last resort, but by making certain that violations of the Constitution by those at the helm of government are challenged and reversed.
In the modern world, government raised forces, whether troops or police, are not armed with flintlock firearms. Police forces always carry modern arms. The purpose of such arms is self-defense. Every American citizen is guaranteed the same right by the Second Amendment. In order for Americans to keep their government and its forces under their control, as the Constitution gaurantees, the people, at a minimum, have the right to keep and bear the same type of arms that police are provided. These arms would include modern pistols, shotguns, and rifles, especially, although not limited to, those chambered for the rounds designated for use by American troops.