Don't you threaten me, you little son-of-a-bitch!
AR-15s are not used by the military but let's be very clear about one thing ... the 2nd Amendment was specifically created to protect civilian ownership of military grade weapons. "Weapons of war."
Amendment IIA 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.
Here are quotes from two Democrats, before the Dem Party became the Hate America Party, that speak specifically to the premise of civilians using arms for war...
"By calling attention to 'a well regulated militia,' the 'security' of the nation, and the right of each citizen 'to keep and bear arms,' our founding fathers recognized the essentially civilian nature of our economy. Although it is extremely unlikely that the fears of governmental tyranny which gave rise to the Second Amendment will ever be a major danger to our nation, the Amendment still remains an important declaration of our basic civilian-military relationships, in which every citizen must be ready to participate in the defense of his country. For that reason I believe the Second Amendment will always be important."President John F. Kennedy
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"Certainly one of the chief guarantees of freedom under any government, no matter how popular and respected, is the right of citizens to keep and bear arms. This is not to say that firearms should not be very carefully used and that definite safety rules of precaution should not be taught and enforced. But the right of citizens to bear arms is just one more guarantee against arbitrary government, one more safeguard against a tyranny which now appears remote in America, but which historically has proved to be always possible."
Vice President and Senator Hubert H. Humphrey
The primary reason for the 2nd Amendment was to protect the citizen's right to own and use weapons of war to fight, as civilians, any threat to our sovereignty foreign or domestic.