Washington Post:

• The numbers: About 1 in 20 U.S. adults — roughly 16 million people — own at least one AR-15, according to new polling data from The Post and Ipsos.
• How it happened: The industry embraced the gun’s political and cultural significance as a marketing tool after a federal assault weapons ban expired in 2004, a Post investigation found.
• One fatal consequence: Ten of the 17 deadliest U.S. mass killings since 2012 have involved AR-15s.