I believe Carson's view of the 2nd Amendment has evolved. It may be one of those issues that he perhaps never gave that much thought to before he considered stepping into politics. He appeared on Glen Beck a couple years ago and said something to the effect that people have a right to own weapons, but restricting possession of "assault weapons" in urban areas might be a good idea, however that it would be a local rather than a federal issue. He has since made comments in support of RKBA but nothing specific on black guns.
He also has been regularly writing columns for the Washington Times on a variety of issues.
Would he be a successful candidate or a good President? I don't know. He is intelligent, has morals, integrity, and a lot of good ideas about getting back to the fundamental basics which America was founded on. If nothing else, a Carson candidacy might help to highlight how far off some of the establishment RINO candidates are.