Tim Smith, editor of Airgun Hobbyist, was devoting a whole issue to safety and asked me why I teach a flexed trigger finger position up on the frame at low ready. I realized to my horror I had never addressed that here. So here's exactly what I told Tim, verbatim:
"It goes back to the latter 1970s. A good friend of mine, a police sergeant, was making a felony stop arrest subsequent to a high-speed pursuit. The suspect grabbed the sergeant's 1911 .45 auto and pulled it toward himself, resulting in a severe gunshot wound to the head. The cop was criminally charged with aggravated assault and acquitted, thanks in large part to the expert testimony of the late, great Jim Cirillo, NYPD Retired.
"The cop swore he was holding the pistol on safe with his thumb on the safety, his finger straight and in contact with the front edge of the trigger guard. Reconstruction indicated that as he reflexively tightened his hand and pulled back, the thumb closed down (wiping the safety into the fire position) and his taut finger simultaneously snapped back into the trigger."
Analyzing what went wrong led to my developing the finger-flexed-on-frame register position. I began teaching it in the late '70s and it first appeared in print in my 1984 book StressFire.
AVOID THE UNINTENTIONAL
If, in an extreme stress situation, your finger does enter the triggerguard from the flexed position, it will be coming across the trigger, not straight back into it! I've never claimed this can prevent an unintentional discharge 100 percent of the time, but it will vastly reduce the chance of it happening. You can see (and feel) this for yourself. With your unloaded gun pointed in a safe direction, put your trigger finger on the front edge of the guard, and mimic a spasm that closes the finger. Because your finger has been held taut on the front of the guard, it will strike the trigger with more than enough force to fire. I am aware of cases where this happened with fatal results. One was in Texas involving a GLOCK 22 with an NY-1 trigger (pull weight around 8 lbs.). The other was in New York City involving a GLOCK 19 with an NY-2 trigger whose pull measured 11.5 lbs.
Now try this again (dry-fire!), but starting with your trigger finger flexed and the tip of the finger--not the pad--on the frame above the triggerguard. Your finger will go across the face of the trigger, greatly reducing the likelihood of unintended discharge.
Bear in mind a straight finger along the frame need...