The type of gun used in most US homicides is not an AR-15

Handguns are responsible for nearly two-thirds of the nation’s gun murders.

This report is a part of "Rethinking Gun Violence," an ABC News series examining the level of gun violence in the U.S. -- and what can be done about it.

Ty Dodson, a 6-year-old boy from Kentucky, had just started kindergarten when he went to visit his grandmother in Tennessee.

While at his grandma's home in September 2019, Ty was shot and killed, allegedly by his step-grandfather, with a .357-caliber revolver, according to Nashville police. The man also allegedly shot and killed his wife, Ty's grandmother, before dying by suicide, police said. Ty's 4-year-old sister ran to a neighbor's and survived unharmed, police said.

While semi-automatic rifles such as the AR-15 are a major flashpoint in the gun control debate and are often the focus of attention following mass shootings, there are only about 20 million assault rifles in the United States, a fraction of the estimated 400 million guns in the country. Instead, according to ABC News contributor and former FBI agent Brad Garrett, handguns account for the most gun murders in the U.S.