Unfortunately, once we covered up the trigger guard, the path was paved for negligent discharges going back into the holster. Carelessly leaving the finger inside the trigger guard when reholstering will result in the holster helping the finger press the trigger. That’s not the holster’s fault, it’s the user’s.
tacticalprofessor 
Great points. I have a couple of additions. The first is ND’s in the holster. Don’t forget that things like drawstrings can find their way into the trigger guard. Also some guns are not a good match for the holster being used. I know of one case where an off duty officer was shot by a CZ carried hammer down in an IWB with no retention strap. The hammer was snagged by some object and fell with enough force to set the round off.
Second Blue guns aren’t real expensive, but training barrels are cheap. Also airsoft guns work well, and laser trainers while expensive are the best.
Reblogged this on disturbeddeputy and commented:
Index your finger on the frame above the trigger and NEVER let it wander when you are not actually engaging the target.