Early constitutional commentators and the right to arms
The early American constitutional commentators are a primary source for "original understanding" (which differs from "original intent" in that it emphasizes, not what did the Framers intend, but rather what is the likely intent of the Americans as a whole who ratified the Constitution and BoR).
St. George Tucker's 1803 edition of Blackstone's Commentaries was the first American edition of that work, and generations of American lawyers trained with it. Tucker was appointed to the state Supreme Court by Jefferson, and to the Federal bench by Madison. Tucker's edition sets out Blackstone's discussion of the English Bill of Rights:
5. The fifth and last auxiliary right of the subject, that I shall at present mention, is that of having arms for their defence40 suitable to their condition and degree, and such as are allowed by law.41 Which is also declared by the same statute 1 W. & M. st. 2. c. 2, and it is indeed, a public allowance under due restrictions, of the natural right of resistance and self-preservation, when the sanctions of society and laws are found insufficient to restrain the violence of oppression.
To which Tucker adds two footnotes (bear in mind that the original bill of rights had two amendments that were not ratified by 1803, so the Second Amendment was then the Fourth):
40. the right of the people to keep and bear arms shall not be infringed. Amendments to C. U. S. Art. 4, and this without any qualification as to their condition or degree, as is the case in the British government.
41. Whoever examines the forest, and game laws in the British code, will readily perceive that the right of keeping arms is effectually taken away from the people of England. The commentator himself informs us, Vol. II, p. 412, "that the prevention of popular insurrections and resistence to government by disarming the bulk of the people, is a reason oftener meant than avowed by the makers of the forest and game laws."
William Rawle was likewise prominent in American legal and political circles. George Washington offered him the post of first Attorney General, which he declined for personal reasons, and he served in the Pennsylvania legislature that ratified the Bill of Rights. His 1825 book, A View of the Constitution, became a standard con law text in early American universities. Rawle's view of the Second Amendment is even more robust:
In the second article, it is declared, that a well regulated Militia is necessary to the security of a free state; a proposition from which few will dissent. Although in actual war, the services of regular troops are confessedly more valuable; yet, while peace prevails, and in the commencement of a war before a regular force can be raised, the militia form the palladium of the country. They are ready to repel invasion, to suppress insurrection, and preserve the good order and peace of government. That they should be well regulated, is judiciously added. A disorderly militia is disgraceful to itself, and dangerous not to the enemy, but to its own country. The duty of the state government is, to adopt such regulations as will tend to make good soldiers with the least interruptions of the ordinary and useful occupations of civil life. In this all the Union has a strong and visible interest.
The corollary, from the first position, is, that the right of the people to keep and bear arms shall not be infringed.
The prohibition is general. No clause in the Constitution could by any rule of construction be conceived to give to congress a power to disarm the people. Such a flagitious attempt could only be made under some general pretence by a state legislature. But if in any blind pursuit of inordinate power, either should attempt it, this amendment may be appealed to as a restraint on both.
And somewhat later in the century, came Principles of Constitutional Law, by the famous jurist Thomas Cooley. He wrote:
The amendment, like most other provisions in the Constitution, has a history. It was adopted with some modification and enlargement from the English Bill of Rights of 1688, where it stood as a protest against arbitrary action of the overturned dynasty in disarming the people, and as a pledge of the new rulers that this tyrannical action should cease. The right declared was meant to be a strong moral check against the usurpation and arbitrary power of rulers, and as a necessary and efficient means of regaining rights when temporarily overturned by usurpation.
The Right is General. — It may be supposed from the phraseology of this provision that the right to keep and bear arms was only guaranteed to the militia; but this would be an interpretation not warranted by the intent. The militia, as has been elsewhere explained, consists of those persons who, under the law, are liable to the performance of military duty, and are officered and enrolled for service when called upon. But the law may make provision for the enrolment of all who are fit to perform military duty, or of a small number only, or it may wholly omit to make any provision at all; and if the right were limited to those enrolled, the purpose of this guaranty might be defeated altogether by the action or neglect to act of the government it was meant to hold in check. The meaning of the provision undoubtedly is, that the people, from whom the militia must be taken, shall have the right to keep and bear arms, and they need no permission or regulation of law for the purpose. But this enables the government to have a well regulated militia; for to bear arms implies something more than the mere keeping; it implies the learning to handle and use them in a way that makes those who keep them ready for their efficient use; in other words, it implies the right to meet for voluntary discipline in arms, observing in doing so the laws of public order.
The point is simple. At the time of the ratification of the Bill of Rights, and indeed for a century thereafter, all major American legal commentators understood that the Second Amendment was an individual right. The "collective rights" view is very much an invention, and a recent one.