Giving up little.
What we give up when we keep the finger "in register" on the drawn gun is a very tiny sliver of time. Veteran trainer Manny Kapelsohn proved it many years ago. Retired cop Lance Biddle, now active in iDpA (International Defensive Pistol Associaton, www.idpa. com), proved it yet again in November '09 at one of the creative and educational matches he runs monthly at The Gun Shop in Leesbuig, Florida. When Lance was told by recent graduates of two different police academies they'd been taught to take suspects at gunpoint with fingers on triggers, he went back to an object lesson he had been teaching for many, many years.
Biddle created a match stage with multiple strings of fire, all electronically timed. Half the time the shooter began on target with trigger finger on frame, and half the time on target with the finger actually on the trigger. They were instructed to fire "on the beep," and their times were meticulously recorded. A third of the firing was headshots, the rest aimed at the torso, but all shot at five yards.
The results? With relatively precise headshots, the average time to get one shot on target was 0.437 seconds, with finger starting on trigger. Biddle's group recorded a low of 0.21 and a high of 1.24 seconds among the field of 22 competitors. With the finger outside the trigger guard to start, average time for the same headshot was 0.732 seconds, with a fastest of 0.26 and a slowest of 1.69.
The difference? About 0.295 seconds on average--less than a third of a second.