the only problem with an AR is the same problem that exists with a handgun, or in fact, any firearm, that its only intended use is to do harm to something, or someone else, for whatever reason. that being said, this problem does not remove the right of every american citizen to bear arms, and as the constitution does not specify specific arms, then if an american wants to have an AR in their living room, then the government should not be able to stop them, due to the fact that its only problem, is one shared by all guns, and it has no other specific specifications that make it any more or less capable of killing someone.
A gun can't shoot someone without the human there pulling the trigger. These days the whole world is crazy. Shootings at schools,restaurants,stores.terrorist organizations,gangs.The people with the guns are the problem. The guns are inanimate objects and therefore can't kill people on their own.