"A 2004 study by the National Academy of Sciences found "no credible evidence that 'right-to-carry' laws, which allow qualified adults to carry concealed handguns, either decrease or increase violent crime." "
IIRC, the National Academy of Sciences is a left wing org, and they would have weighted the study as much as they could to the leftoid narrative. The best they could come up with with "No effect". LOL.