Let's ask the Founding Fathers.
A well regulated militia being necessary to the security of a free State, the right of the People to keep and bear arms shall not be infringed.
oh yeah..
I dont see anything there about full auto.
In fact, in the military they don't issue full auto weapons to infantry. They are frankly fairly useless. And I own one.
A well-regulated militia, moron, means a militia properly outfitted, trained, and prepared to take on any probable threat.
Now, can the militia truly be called well-regulated without the weapons necessary to do their job, which is to stand up to the Army in the case of tyranny? Can we resist tyranny with longguns and pistols? No! We must possess in our homes nothing less than such rifles as have proven themselves suitable for resistance in conflicts around the world, and the organized militia (which was morphed into the 'National Guard') must possess such vehicles and heavy weapons (ordinance) as can see us through a sustained battler against any foreign or domestic threat to liberty.
That is what the Second Amendment is all about.