Prof. Doug Berman (Sentencing Law & Policy) has an interesting post on this, focusing on the six states that don’t have state constitutional right to keep and bear arms provisions. I would add to that list Massachusetts, which has a provision that has been interpreted as not securing an individual right, and Hawaii, which has a provision that has not been interpreted definitively one way or the other; both of these are relatively high-regulation states, and thus more likely to have potentially vulnerable gun control laws.