I’ve heard the double-tap reference from dramas about the SAS. (Not saying they originated it).
“Mouth-shot, double-tap” has the sort of unsqueamish pragmatism you want in a hostage situation.
I’ve heard “double-tap” before the Zombie movie reference ... Zombieland just tends to be the reference that comes to mind to most civilian non-assassins (haha).
I think ‘double-tap’ is a pretty common special forces term ... good way to drop a guy and make sure he ain’t getting back up.
I’ve always heard of a double-tap to the head — but apparently it refers to just a quick two-shot succession anywhere on the body (pause just long enough to reaquire the sights). The technique apparently originated after full-metal-jacketed bullets — where a single shot won’t necessarly do enough damage to keep a guy down. According to Wikipedia, “The tactic is still used today by firearms handlers, police tactical teams, military personnel, counter-terrorist combat units, and other special forces personnel.”
SnakeDoc