First, and foremost, don't use the FBI definition. Use the Brady definition for mass killing, which equates "4" to a "mass" of people, and even then requires that they combines counts of events that took place at more than one location and at different times, then pile on using killings during robberies, family feuds, stabbings, blunt force objects and "other" methods. Doing that you can make the American landscape look worse than Little Big Horn on a summer day in July. Oh, above all, do NOT mention that of the real mass shootings, about 95% were done by people fresh of psychotropic drugs or with a life long history of mental illness. That might suggest that the problem isn't the availability of legal guns or legal gun owners who follow all rules and regulations, regardless of how they trample the 2nd Amendment.
http://www.usatoday.com/story/news/nation/2013/09/16/mass-killings-data-map/2820423/
