Jim Geraghty of National Review and Greg Corombos of Radio America recoil at the horror of four people killed in a Tennessee mass shooting, but the shock turns to anger at the news that authorities took away the shooter's guns last year, left them with his dad under orders to keep the guns locked up, but the dad gave the weapons back to the shooter.  At the same time, they marvel at the heroism of James Shaw, Jr., who attacked and disarmed the shooter without any weapons of his own.  And they discuss Tennessee Sen. Bob Corker's "endorsement" of Marsha Blackburn in the race to replace him - in what might be the most pathetic endorsement we've ever seen.