According to what I`m reading in this thread, the common denominator is that they went off "in a holster", being worn on a person. Have none of them fired in a vehicle, not holstered on the person. Have any fired laying on a nightstand? While loaded in a safe or any other location? If they are all firing while in a holster and a person was wearing the holster, I suspect the trigger finger was involved.
On video, there are multiple instances of an officer with their P320 strapped into a holster. They aren't holstering it; it's already in the holster, snapped in, and has been in the holster for (in some instances) several hours. On the video, the P320 discharges, while still strapped in the holster.


