“Shall-issue” laws require authorities to issue concealed-weapons permits to anyone who applies, unless the applicant has a criminal record or a history of mental illness. A large number of studies indicate that shall-issue laws reduce crime. Only one study, an influential paper in the Stanford Law Review (2003) by Ian Ayres and John J. Donohue III, implies that these laws lead to an increase in crime. We apply an improved version of the Ayres and Donohue method to a more extensive data set. Our analysis, as well as Ayres and Donohue’s when projected beyond a five-year span, indicates that shall-issue laws decrease crime and the costs of crime. Purists in statistical analysis object with some cause to some of methods employed both by Ayres and Donohue and by us. But our paper upgrades Ayres and Donohue, so, until the next study comes along, our paper should neutralize Ayres and Donohue’s “more guns, more crime” conclusion.