In the US, over the last 30 years large-capacity ammunition magazines — which hold more than 10 rounds — have proliferated, allowing assailants to become much more destructive and significantly more deadly. The Citizens Crime Commission of New York City has launched a report analysing shootings since 1984 that resulted in more than four deaths. Mass shootings were dramatically less deadly between 1994 and 2004, when the federal Assault Weapons Ban was in effect. Overall, shooters who used large-capacity magazines between 1984 and 2012 killed or injured 161 percent more people than those who did not, according to the study. Source: http://www.nycrimecommission.org/pdfs/CCC-MayhemMultiplied.pdf