Terminology

Double-Tap: (AKA Hammers) The shooting technique where it's assumed that one shot might not stop the target. This involves two rapid shots, with no pause to re-align the sights between the two. This means that the second shot will be affected by the recoil of the first, but, it is faster than:
Accelerated Pairs: Similar to the double-tap, but the operator takes the time to re-align their sights after the first shot.
Stopping Power: A measurement of the ability of a bullet or weapon to stop a target. This does not necessarily mean killing them, but merely stopping them from being a threat. For example, a beanbag round fired from a 40mm grenade launcher will not necessarily kill someone (unless fired at the head), but it will stop them, by knocking them to the floor and stunning them.
Teuler Drill/Distance: It has been accepted in courts of law, that if confronted by a knife-wielding assailant, that in the time it takes to draw, ready and fire a stopping shot, the knife-wielder can cover a distance of about 21 feet, and deliver a potentially fatal wound. In effect, lethal force can be justified if a knife-wilder closes to that distance. Useful to DG agents looking for justification of their execution of a sacrifical-knife carrying cultist.
the driull was named for Seargent Dennis Teuller who proved that given a 1.5 second time, an assailant could close and grapple/stab the shooter from a distance of 21 feet.
El Presidente: A particularly nasty training drill designed by Jeff Cooper. Three targets are set up one yard apart at ten yards range. Starting with your hands up, facing away from the targets, turn draw and shoot two rounds into the a-zone of each target, reload and shoot two more. These targets are assumed to be rifle-wielding attackers, in reality, it would normally result in the death of the pistoleer without lots of luck and skill.
There are easier variations of the excercise known as the vice president and the demi-presidente.
Failure Drill: Training to account for body armour. After delivering a double-tap to the target's centre of mass, the shooter re-assess, realises that the opponent has not been stopped, and shoots again for the head (unarmoured). It is not the automatic delivery of two to the chest and one to the head, but rather an assessment between the two.
This was also called the Mozambique drill by Jeff Cooper in his commentaries.
Tactical Reload: A reload during a "lull" in combat when a partially fired magazine is replaced with a fully loaded one. The advantage of this is obvious, you now have a fully loaded gun again. The disadvantages include; the time and distraction of re-loading the gun, the fact that you may be surprised whilst re-loading with only one shot in the chamber, OR, if your weapon has a magazine safety, you now have an innefective club.
What you do with the half-sed magazine is the subject of some debate too, leave it on the floor, place it back in amongst your fully-loaded magazines , put it somewhere else so you know the difference, or fill it with loose rounds again?
:
: