What Makes the AR-15 Rifle 'America's Gun'?

ar-15
The AR-15 semiautomatic rifle has been called "America's gun," but it also has a dark history.
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It's been called "America's Gun." The semi-automatic weapon known as the AR-15 — sometimes referred to by its many fans as "the Black Rifle" — is by some estimates the most popular rifle in the United States, with an estimated 4 million in circulation. And it's back in the news once again.

Law enforcement officials initially claimed that Aaron Alexis used an AR-15 to kill 12 people and injure eight before he was killed in Monday's mass shooting at the Washington Navy Yard in the nation's capital. However, officials later confirmed that Alexis used a shotgun (and possibly a handgun) and was not in possession of an AR-15 during Monday's shooting, though he is believed to have rented and practiced with an AR-15 at a Virginia gun range less than two days earlier.

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Marc Lallanilla
Live Science Contributor
Marc Lallanilla has been a science writer and health editor at About.com and a producer with ABCNews.com. His freelance writing has appeared in the Los Angeles Times and TheWeek.com. Marc has a Master's degree in environmental planning from the University of California, Berkeley, and an undergraduate degree from the University of Texas at Austin.