The myth of the “double tap” or “shoot until the threat is down” is a result of poor caliber selection by law enforcement and militaries. If your weapon system requires you to shoot two projectiles or continue shooting at the threat until it goes down then you have selected a poor caliber.
When it comes to caliber selection one should select the largest diameter moving at the fastest rate possible. The prevalence of the AR-15 with 30-round and 40-round magazines is pointless because trainers now teach their students to utilize the double or triple tap on all target engagements. The reality is that with such training practices you are actually limiting yourself to only 15 or 10 rounds due to a training methodology that relies on an inadequate caliber selection. The fix is to simple engage the target more however the fault with this methodology is that it assumes your target will remain in the same place and neither he nor his comrades will attempt to defend himself. This training methodology is a departure of centuries of firearm training doctrine which had been taught since the advent of gunpowder. That being, only one shot per target is required and if for whatever reason that one shot was not adequate then you needed a larger and more powerful cartridge. The U.S. Army had developed the .45 ACP specifically due to these reasons after intense battles with Filipino guerillas. To add, until only recently Texas Department of Safety State Troopers carried 44 Magnum revolvers as it was found it was a reliable man stopper and didn’t put Officers lives in danger by requiring two or three shots in order to neutralize the threat.
In many localities hunting with 9mm and 5.56 NATO is illegal as game wardens have found such cartridges are inadequate at reliably and humanely harvesting game animals. Take into account that most game animals such as a male deer or boar weigh approximately 110 to 170 pounds which is roughly the size of a healthy adult male and the argument of magazine capacity versus cartridge selection goes out the window. It is odd that such cartridges are deemed inadequate for hunting yet are routinely used by military and law enforcement. Hence we have the myth of the double tap or “shoot until the target stops”. The truth is that caliber selection is chosen by government bureaucrats who have little to no real world experience in gun fights nor hunting. Civilian shooters concerned with self defense are not limited to state sponsored training nor caliber selection.
If one was to explain the government cartridge selection methodology to a hunter on why he should consider using .223 Remington or 9mm for hunting it would be met with heavy skepticism. Hunters only have one shot to successfully harvest a game animal. If an animal is hit with an inadequate cartridge they won’t simply stand there and wait to be hit again, they will run. I have personally witnessed a boar with a hole big enough to see daylight through run for a full mile before collapsing. Humans are no different and whether it be trained soldiers or gang members, people will attempt to avoid threats as quickly as possible. There are millions of youtube and liveleak videos showing people being shot by gang members and law enforcement who then immediately ran away if they were able to do. Those who had been shot and didn’t run had been shot in the central nervous system or suffered a wound that immediately paralyzed them such as a spinal cord hit.
Additionally let’s take into account that average of rounds expended in a shooting is 1.98 to 2.1 rounds fired. The training methodology of engaging multiple targets with controlled pairs is fantasy training. You cannot train fast to engage three to four threats with double taps. This training methodology is complete fantasy and will get someone killed. Any hunter who is pursing game will always ensure that his caliber selection is fully sufficient to drop his game with ONE SHOT. Not a double tap, not a “controlled pair” and not “shooting until the target is down”…he ensures he can drop the animal with ONE SHOT.