Another issue without a metric...
In getting my CHL here in Texas, the first thing we were taught is that no matter what the circumstances, as soon as your concealed handgun was unconcealed, you have broken the law. The circumstance & outcome of the event will determine if charges are brought against you.
During my renewal, I heard several carriers tell stories of how once they made known they were armed, the threat very quickly left. Illegal? YES! How often it happens with a positive outcome, we'll never know. I guess we'll never know if it's a significant factor either in CC reducing crime.
Just food for thought.