The short of it: the current debate over gun control has almost nothing in common with the debate that our founding fathers were having.

Starting with the comma point though: I haven't heard of the typos before, but I have heard the rest. This is indeed a ubiquitous argument. There's even a pretty common meme out there that goes so far as to say that a single comma gave Americans the right to own guns. I can't comment much on the validity of this argument. I'm sure as far as the contemporary Supreme court goes, anything is possible. If we're asking however what the original intent of the 2nd amendment was, there's a much more straightforward place to look.

In the Constitutional Convention, here the debate is clearly concerned with how to avoid the creation of a standing army, and so by extension, how to ensure that the militia remains a viable fighting force. That is, if "viable" is even the right word. The basic tension around this subject seemed to be that while on paper the militia was the ideal guarantor of a free republic, on paper, their performance left much to be desired. The "shot heard around the world" was the fruit of militias, but the victory at Yorktown was the culmination of Continental Regulars. Which do you choose?

There's a famous moment at the Convention. In a discussion about standing armies, Elbridge Gerry suggests a limit on the standing army of, "two or three thousand men," to which Washington, "silent for weeks now, turned in his chair and in a stage whisper proposed that the Constitution also include a provision declaring that, “no foreign enemy should invade the United States at any time, with more than three thousand troops.”

Anyone that knows how taciturn Washington typically is gets double the humor out of this anecdote. This is one of the fun parts about studying this angle though. Washington, understandably, has some things to say here.

To Gerry's credit however he was prescient other things. Namely he correctly anticipated that the Constitution-as-is would be poorly received by the public, and so it would be left to measures like the 2nd amendment to assuage peoples' fears about a tyrannical central government. At least that is the long and short of it. And where is the militia today? That gives you a hint about how effective the 2nd amendment ultimately was.

There are many more details in between, truncated in the interest of time/length. Let me know if there's anything further required.

Sources

Waldman, Michael. The Second Amendment: A Biography. Simon & Schuster, 2014.

It sounds like a wive's tale. The problem with most contemporary discussion of the 2nd amendment is that everyone forgets that prior to the doctrine of incorporation The Bill of Rights only constrained federal government.

At the time the Constitution was ratified, several states had the explicit right to bear arms and/or serve in a militia in their state constitutions. Here's the right to bear arms in Pennsylvania's Constitution of 1776:

That the people have a right to bear arms for the defense of themselves and the state; and as standing armies in the time of peace are dangerous to liberty, they ought not to be kept up; And that the military should be kept under strict subordination to, and governed by, the civil power.

The Federalists did not think a federal bill of rights was necessary, but it became clear that without one, the Constitution would not be ratified. The purpose of the Bill of Rights was not to constrain state governments, but the federal one.

States, at the time the Constitution was ratified, were much more like sovereign nations than our modern notion. Each had long histories of self-government and individual rights. So the impetus for the Bill of Rights wasn't a fear that Massachusetts or Virginia would suddenly deprive their citizens of rights to assembly, worship, arms, et al, but that the newly formed federal government would.

In this context splitting hairs about commas is absurd. As second amendment scholar Glenn Reynolds notes:

Madison's own proposal for integrating the Bill of Rights into the Constitution was not to add them at the end (as they have been) but to interlineate them into the portions of the original Constitution they affected or to which they related. If he had thought the Second Amendment would alter the military and/or militia provisions of the Constitution he would have interlineated it in Article I, Section 8, near or after clauses 15 and 16.51 Instead, he planned to insert the right to arms with freedom of religion, the press and other personal rights in Section 9 following the rights against bills of attainder and ex post facto laws.

Given the debate of the time and well-established history of individual rights in the several states, the wording of the second amendment would've been clear to any contemporary reader regardless of commas.