This was actually discussed BEFORE the Constitution was designated the law of the land (as well as Jefferson's preference to an end to slavery). Sam Adams had a lot to say about it, and his writings are easy to find, as are Franklin's. The "militia" was supposed to be well practiced in the use of current military firearms, so that they could be called up at a moment's notice for the common defense. The AR-15 is ideally suited for this, because it is so easy to use, maintain, and affordable to everyone. On the downside it is easy to abuse, as well.
Still, the gun is not the problem.
The problem is our society has grown more immature, while there is no security in place to protect immaturity from accessing lethal means.
We are at a crossroads now where the legal age to own firearms may be raised above the age for military indoctrination. Instead, I think we should mentor our kids into familiarity with firearms, and every time someone buys their first weapon they should be forced to buy a gun safe. The Sheriffs could then have surprise inspections to see the safes are in proper use. Then, if an adult screws up and their kid gets out a gun and goes on a rampage the adult would be prosecuted too. The mentors could also assess the mental health and maturity of individuals and their ability to buy firearms curbed as needed.
Just a suggestion you'll never see come out of Washington.
Geeze guys. Read more.