Well, doc, there's lots of reasons.
Bearing Arms seems to sum it up better than I can.
First and foremost:
Police officers and self-defense shooters all learn the same thing: you shoot to stop the threat. The best way to stop that threat is to put bullets in the largest possible part of the body (typically, the upper torso).Dr. Carson may be a nice guy. But his recent comments, and previous ones, show him to be woefully ignorant when it comes to firearms, defensive use of force, and our right to bear modern arms under the Second Amendment.
Carson once said "he'd rather you not have" semi-automatic firearms in large cities. While some claim Carson has since changed his mind, others wonder if he's just choosing his words more carefully.