The Second Amendment protects my right to keep and bear arms. The exact same arms as those wielded by the military.
When the Second Amendment was written, the usual means of fighting was to stand in lines and shoot at each other. Some talk about how dumb this was, ask why rifles weren't used, but given the technology of the time, it was the only way to conduct war.
The rifles of the time worked well as a weapon of asymmetric war, ideal for sniping, ambushes, and hit and run attacks, but it failed as a weapon of regular war. This was because the only ammunition available to anyone of the time was the lead ball. It wasn't until 1847 that the first successful real bullet was introduced. Until then, the only way for rifles to be effective was to force a lead ball slightly larger than the bore of the rifle, to engage the rifling, making it impossible to load a rifle quickly, allowing early riflemen to be easily overran and slaughtered by cavalry or advancing musketeers should they try to hold a battlefield.
The musket, on the other hand, was specifically designed as a weapon of war. Because it was a smooth-bore firearm, it could be loaded quickly (although at the expense of accuracy). This made musketeers harder to overrun, while forcing them to engage at much shorter distances.
While the rifle wielding irregular forces harried the British forces, there were a few times when the rebels had to hold or take ground, and for that they had regulars, trained by the Baron von Steuben of Prussia.
The Second Amendment was written to protect our right to bear the same arms as those used by the military - weapons which at the time were useful only for war and self-defense. It applies to all advances in military technology.
Right after the Revolution, a man could go and buy the exact same weapon as used by our nation's army.
Nowadays, we have people agitating for more gun control. While its perfectly legal to buy tanks and military fighter jets, such equipment is prohibitively expensive, even for older models of Soviet and Russian equipment, which starts out much cheaper than the equivalent Western models. I can't afford a modern military vehicle, I can only buy a fully automatic firearm which predates the May of 1986 "Firearm Owners Protection Act" (and even then I have to pay a tax), and now the jackwagons in government, both federal and local, are acting to further restrict firearms rights.
I cannot own any modern military weapons, in fact, the best that I can buy are reduced capability clones. And now the inconsiderate, ignorant, pinko commie, refugees from Woodstock *ssholes in positions of authority wish to further infringe upon my Constitutional right to keep and bear arms. The right which the Second Amendment says "shall not be infringed". All gun laws are unconstitutional. There is no such thing as reasonable compromise.