"Mass-shooting related homicides in the United States were reduced during the years of the federal assault weapons ban of 1994 to 2004.... Recently, 75% of members of the American College of Surgeons Committee on Trauma endorsed restrictions to “civilian access to assault rifles (magazine fed, semiautomatic, i.e., AR-15),” and 76% of the Board of Governors were in favor of a limit to “… civilian access to ammunition designed for military or law enforcement use (that is, armor piercing, large magazine capacity).” In 2015, the American College of Surgeons joined seven of the largest most prestigious professional health organizations in the United States and the American Bar Association to call for “restricting the manufacture and sale of military-style assault weapons and large-capacity magazines for civilian use.” This analysis adds evidence to support these recommendations.... Our results add to the documentation that mass shooting–related homicides are indeed increasing, most rapidly in the postban period, and that these incidents are frequently associated with weapons characterized as assault rifles by the language of the 1994 AWB. ...taken in the context of the increase in mass shootings in the United States, these results support the conclusion that the federal AWB of 1994 to 2004 was effective in reducing mass shooting–related homicides in the United States, and we believe our results support a re-institution of the 1994 federal assault weapons ban as a way to prevent and control mass shooting fatalities in the United States."