On October 16, a 16-year-old gunman fired at a parent in a vehicle, then shot his way through a locked door at Silver Rail Elementary School in Bend, Oregon, killing three children and a teacher. Caleb Giammanco, a 36-year-old carpenter whose two daughters attend the school, retrieved a legally secured pistol from his vehicle, followed the shooter inside and killed him before police arrived. The victims include five-year-old Rome Summer and 25-year-old teacher Megan Lambert; two others are unidentified at their families' request. Police say the suspect used a Maverick 88 shotgun taken from his home and carried 44 more rounds; two law enforcement officials say the shooter's mother bought the gun around his birthday in August and is cooperating.…