
Since 1986, Congress has forbidden gunmakers from producing fully automatic weapons for the civilian market, leaving machine gun aficionados to collect older models, and then register them. The National Firearms Act of 1934 required owners of fully automatic guns to register the weapons with the federal government. Some gun experts insist that the term “assault rifle” only refers to a very specific set of weapons: those that are fed ammunition from a detachable magazine, and can switch between semiautomatic and fully automatic fire, a capability known as “select fire.” By that narrow standard, the number of assault rifles in private hands is very small. The numbers are hazy for two main reasons: There’s no official criteria for what qualifies as an “assault rifle,” and the government doesn’t keep detailed data on the different types of firearms owned by Americans.

That makes it all the more frustrating that there is no way to know precisely how many of these rifles exist in the United States. Courts assess the popularity of the weapons when deciding whether politicians can ban them. So it’s reasonable to wonder: How many assault-style rifles do Americans actually own? To their fans, guns like the AR-15 are versatile, customizable, and uniquely fun to shoot.

To their foes, they are the tool of mass murderers, made infamous at Sandy Hook, San Bernardino, Las Vegas, and Parkland.

Assault weapons loom large in the American gun debate.
