I compiled this from annual reports from the FBI, specifically the Uniform Crime Report. It is meant to explicitly describe just what types of firearms pose the greatest threat, from a generally reputable source, to public safety, in terms of total murders committed. The years covered are 1991 (earliest data available from the FBI-UCR web site) to 2016 (latest year with a final report). It consists of two files. One is total murders and the other is just murders committed with some type of firearm.