The Militia Acts, some of the first acts of Congress, predominantly, if not completely, written by the same folks who had just written the Bill of Rights, make no sense without the expectation that nearly every able man was armed. The Militia Acts are linked through the first link in comment# 370. Here's section VII:
"VII. And be it further enacted, That the rules of discipline, approved and established by Congress, in their resolution of the twenty-ninth of March, 1779, shall be the rules of discipline so be observed by the militia throughout the United States, except such deviations from the said rules, as may be rendered necessary by the requisitions of the Act, or by some other unavoidable circumstances. It shall be the duty of the Commanding Officer as every muster, whether by battalion, regiment, or single company, to cause the militia to be exercised and trained, agreeably to the said rules of said discipline."
That was the extent that the militia was to be "well regulated" in the Second Amendment, i.e. to the standard of the Continental Army as propounded by Baron Von Stueben in 1779, accepted by George Washington and approved by Congress. That's what was meant in the prefatory clause of the Second Amendment by "well regulated," they were expected to be trained to the standard of a Regular Army soldier, even though they were part of a state militia. If you read the link to the Militia Acts completely, you'll understand that they could be federalized at the drop of a hat. The Founding Fathers feared a large standing "regular" army. They expected that the militia with their own weapons could be a viable substitute for a large standing, aka regular, army.
N.B. The U.S. Army Sixth Infantry Regiment is called "The Regulars", as in Regular Army, not the regulated army. I had been assigned to it a while ago, so I can attest to its name.
I am in total agreement with the concept that the 2nd amendment is an individual right rather than a collective one. The problem is that Barron v Baltimore is settled law and the Parker decision will not affect any state laws.
Now the supreme court could rule that the Bill of Rights cannot be incorporated selectively (our best hope) or that the unique language of the 2nd makes it unique among the 8 and has always applied to all forms of government.
The courts, even after the passage of the 14th amendment, have had opportunity after opportunity to overturn Barron v Baltimore but all of them for 170 years have refused to do so.