Callcut RA, et al. - Employing control charts, a method to analyze how a process changes over time in response to nonroutine events, researchers sought to investigate how US mass shootings influence California (CA) gun sales. The CA Department of Justice and monthly fatalities provided monthly gun sales from the CDC Wonder Death Certificate Registry. After-action reports, news media, and court proceedings were assessed to obtain mass shooting events. In CA, individual gun sales of 9,917,811 were reported with a median monthly rate of 41,324 (range, 20,057–132,903). Monthly, deaths of around 263 people from firearms were reported (124 homicides, 128 suicides), totaling 53,975 fatalities from 1999 to 2015. During this study period, 15 of 21 current deadliest mass shootings occurred with 40% from 2012 to 2015. As per the analysis, more frequent gun sales are reported since 2012. Both mass shootings and legislative changes enacted in response to these shootings seemed leading to an additional increase in these sales.