Why would I challenge a Bradley with an AR-15, I don't own one, but if I did I'd not use it against a Bradley. I'd use a few of thermite devices in the middle of the night while the crew is away.
It also depends on where you are. The Chechen Freedom Fighters put together three man teams. One with an RPG, one with a light machine gun of the M240 class, and one with an AK. When they needed additional firepower they combined into two, or three, or more teams at the same time.
Keep in mind that I'm not an advocate of this sort of scenario, but it still bears contemplation.
As far as the original topic is concerned, advocating the ban or restriction of only one gun is all it should take to remove a candidate from consideration.