only when the pistol released in an unexpected manner did the finger go to the trigger
If it's "unexpected" its poor training and a violation of the 4 basic rules.
Accident vs Negligent Discharge??? If you were to separate the two, the only "accident discharge" I've seen was a loaded gun in a fire, where the heat caused a cook off. In the hands of the shooter it's a Negligent Discharge.
I've taught defensive retention and take aways to LE officers. And still do. (I understand take aways training is coming back, don't know why it was stopped).
In my classes its impossible to have a negligent or accidental discharge be cause I don't use real guns, I use the "blue guns", or training weapons which you can get for just about every gun available. You ain't gonna shoot yourself in the butt with a "blue gun".
GBRO, reading your post shows, even though you try to portray it otherwise, the accident or negligent discharge occurred from lack of training and following the 4 basic rules of firearm safety.
I'm gonna try to make a video (after it warms up and I can get my wife outside) that shows the trigger finger placement on the Serpa holster as you draw the pistol/revolver. If I can figure it out, I'll post the video.
I suggest anyone who is concerned or interested go to a gun shop, Most have a display of Serpas with blue guns or something similar on the counter for us to play with. Try it. you'll see the Serpa doesn't force your finger in the trigger guard, you have to do that your self.
I don't have a Serpa for my 1911s, but I do know how the safety works. You don't disengage the safety on a 1911 until the point you're ready to shoot and I dis-engage mine as I'm lining up on the target, about the same instant my finger goes into the trigger guard.