The M16 or AR-15 rifle is one of the US’s most divisive symbolsTo gun enthusiasts, it is an effective, lightweight weapon. To anti-gun advocates, it’s a symbol of mass shootings.Experts estimate approximately 16 million adults in the US now own at least one of these rifles.LoadingSomething is loading.Thanks for signing up!Access your favorite topics in a personalized feed while you’re on the go. download the appOn Monday, a mass shooter killed three students and three adults at a school in Nashville. The shooter used two AR-15 rifles in the attack.Semiautomatic rifles, including AR-15s, are becoming more common weapons used in recent mass shootings in the US, according to the National Criminal Justice Association. Since 2012, 10 out of 17 of the deadliest shootings in the country featured an AR-15 rifle, the Independent reported.  AR-15 rifles are light, accurate, and quick. When they were used by the military, they were called M16 rifles.As of 2023, about 16 million adults in the US own at least one, according to polling conducted by The Washington Post and Ipsos. It is the country’s best-selling rifle, but it has also become a divisive political symbol. According to CJ Chivers, when a discussion turns to AR-15s, it stops being rational.”The conversation is burdened by history, cluttered with conflicting anecdotes, and argued over by passionate camps,” Chivers wrote in an article for The New York Times.