The "Old School" train of thought was that in "games" it's quicker to use the slide release after ramming home a mag. In the "street" scenario, it was felt the "tacky-psyche" effect of the nervous system in a life-or-death situation, would make fine motor skills difficult. So, it was taught that the support hand should slingshot the slide, but using the majority of the hand and not just the thumb and forefinger. Those of use who played the games and also worked the streets, tended to use the slingshot method exclusively to avoid mental confusion in the event a real life scenario played out.
