Watch Motherboard's new documentary.
It happened in an instant.
Nicholas Naumkin was at a friend's house the evening of December 22, 2010. Middle school had let out for winter break and the two boys were left home alone, playing video games like Halo and Call of Duty and popping off an otherwise harmless Nerf dart gun. But the playdate would take a violent turn in the kitchen, where Nicholas found himself on the wrong end of an actual gun.
https://motherboard.vice.com/en_us/article/who-killed-the-smart-gun
On a related matter(to me):
http://www.democraticunderground.com/10455050