Zusha Elinson and I have written a book about the bloody and complex story of the AR-15 rifle. Created by the brilliant inventor Eugene Stoner for a private company called ArmaLite, the gun -- through the twists and turns of history including wars, political battles and aggressive marketing and production of the gun for civilian purchase, the AR-15 have become the most popular rifle in the U.S. While millions of Americans use the gun responsibly, others have used it to commit horrifying mass shootings at schools, movie theaters, stores, at concerts -- anywhere people gather. A device created to protect Americans today is being used by extremists and violent loners to kill them. Stoner would be appalled. American Gun is the story of how we got here and how -- possibly -- we can make our country safer while accepting the fact that the AR-15 is ubiquitous.