Anthony Ogline calls it America's rifle: the AR-15. “It's the most popular sporting arm that's ever been produced,” said Ogline, president of Verona Gun Safe, which sells an array of firearms. “A massive amount of these are out there and there's a reason for its popularity.” He's far from alone in declaring his love for the gun. Americans own 10 million AR-15 rifles, according to the National Shooting Sports Foundation. Gun enthusiasts like that it's customizable with lots of accessories, easy to build, lightweight and easy to handle. Most gun manufacturers produce some version of an AR-15. “Honestly they are...