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Mason study calculates rise of assault weapons and high-capacity semiautomatic weapons as 'crime guns'

October 6, 2017

Christopher Koper

Mass shootings such as this month’s massacre in Las Vegas have highlighted debates concerning policies restricting ownership of semiautomatic assault weapons and high-capacity magazines. But there has been little examination of their use in gun crime more generally since the expiration of the federal ban on sales of those weapons in 2004.

George Mason University criminology professor Christopher Koper and a team of Mason researchers, including several students, have updated Dr. Koper’s earlier research on assault weapons for the U.S. Department of Justice.  The tallies represent regional as well as national statistics from a broad range of sources.

Among the findings:

  • High-capacity semiautomatics account for 22 percent to 36 percent of crime guns overall, depending on location, and 41 percent of guns used in murders of police.
  • Military-style assault weapons in particular account for 2 to 12 percent of guns used in crime overall, and 13 to 16 percent of guns used in murders of police.
  • Assault weapons and other high capacity semiautomatics appear to be used in up to 57 percent of firearm mass murders.
  • The share of gun crimes involving high-capacity semiautomatics has increased, depending on location and crime categories, between 33 and 112 percent since the expiration of the federal ban.

Christopher Koper can be reached at 703-993-4982 or

For more information contact Buzz McClain at 703-727-0230 or

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George Mason University is Virginia’s largest public research university. Located near Washington, D.C., Mason enrolls 35,000 students from 130 countries and all 50 states. Mason has grown rapidly over the past half-century and is recognized for its innovation and entrepreneurship, remarkable diversity and commitment to accessibility.