When it comes to the preferred weapons of choice for mass shooters, AR-15 style rifles are high on the list. Variants of the AR-15 were used by gunmen at the Las Vegas Harvest music festival shooting, as well as the Sandy Hook and Marjory Stoneman Douglas school shootings. That gun has taken much of the blame for lost lives, and is itself the target of proposed gun bans across America. Blaise Gainey has more. Lawmakers took some time this week to consider the causes of mass violence -- and how