From Bearing Arms:

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.