Boston Calling

"Every time you hear a piano note, that's another mass shooting." A new way to hear the stark numbers on gun violence. Also: Adam Lankford, a criminology professor, turns to data to explain why the US has more mass shootings than any other country; Susan Cruz, a Salvadoran-American, remembers holding a gun at the age of six; two sisters with different opinions on guns go to a shooting range; we learn about the origins of the Second Amendment; plus we hear from faith leaders all over the US. (Image: Visitors view gun displays at a National Rifle Association outdoor sports trade show on February 10, 2017 in Harrisburg, Pennsylvania. Credit: Dominick Reuter/Getty Images)