Jordan
Clark nailed it.
It works on a continuous motion, with the hand moving in a semi-circle,
and it allows a very smooth, fast presentation because you don't have to
accelerate the weight of the gun upward from a dead standstill...The hand is already moving as it scoops the gun up and out of the holster, and uses
the hand's momentum to overcome the gun's weight.
It's also a very dangerous method unless practiced religiously. Slow-motion
at first, with speed increasing only when the move can be done perfectly..
or as near perfectly as you can manage. Begin practice every day in slow motion, gradually building to about half-speed...No ammo yet.
The other part of the action involves timing the trigger pull to fire the gun
at the same instant that it's on target. This requires starting the trigger pull almost as soon as the gun clears the holster. With a 1911, the safety is wiped off just as the gun clears. The finger touches the trigger when the muzzle is pointed in front of the shooter's foot, and pressure on the trigger begins at that point, with the gun moving upward toward the target...gradually increasing until the gun fires at the instant that the
muzzle covers the target.
I saw a slow-motion sequence of Jordan executing his draw...The trigger was being pulled even before the muzzle was completely clear of the holster. You could see the hammer arcing back almost as soon as he had the gun in his hand. This is why endless hours of dry practice are necessary...and many more required to maintain it. Jordan could execute the move and hit aspirin tablets on a table from the hip 10 feet away about as fast as the eye could follow...and if you blinked at the right instant, you'd never see his hand move. His best time was 27/100ths of a second from signal to shot with a double-action revolver.(Model 19 Smith & Wesson)
Another one of his tricks was balancing a ping-pong ball on the back of his
gun hand at shoulder level, and pulling the gun in time for the ball to fall into the holster...or poking the ball with the muzzle at hip level.
Although the rig is an important part of the speed, any open-topped holster will do. It just won't be quite as fast as with a rig designed for it.
The higher it rides, the slower it will be.
The move also has the advantage of not telegraphing the draw until the gun is in hand. When you reach over the top to get your grip with a high-ride holster, the shoulder hunches before you get your hand on the gun. With the circular scoop, only the lower arm moves at first, and your shoulder doesn't give you away until the gun is half-way to the target.
I'm not as fast as Jordan...