https://www.youtube.com/watch?v=ch7si_VQsGA
In this video they point out that the weight of the trigger, not the pull weight but the actual weight of the physical part itself, seems to be fairly strongly correlated with the rate of these ADs. To me this actually makes sense. The SIG design, to my knowledge, is supposed to be safe because when dropped muzzle up the force will be on the trigger bar to move rearward but on a P320 the trigger bar has to move forward to release the striker. However, it would seem to me that the mass of the trigger vs. the mass of the trigger bar would then be an important balance. If the trigger itself in being driven rearward can exert more force on the trigger bar than the gravity driving the trigger bar rearward it would seem like the possibility for an AD exists.
It's interesting that the lighter X5 trigger and then their cut down stock trigger seem to have no such issues. Moreso to me this plays into a story of how this could have gotten to the market in this state. The trigger on the P320 has changed since it's initial release. It now has a tab on the front of it to supposedly prevent debris from getting into the trigger mechanism and I believe it also has a reinforcement rib inside that I can't remember if was there at the introduction. Now that doesn't sound like much of a difference in weight, but in the video they mention how the X5 trigger is only 6% lighter than the stock trigger and when swapped between different pistols seemed to dramatically reduce the rate of ADs, so not much weight difference seems to be required to start contributing to the problem.
I can imagine a situation in which the original configuration of the P320 was in fact drop safe, even at the slightly different angle as resulted in the ADs in this video, but evolutions over time have taken it into a realm where it still passes the standard tests, but the introduction of an angle causes these ADs. I would also accept someone pointing out that the pistol does still pass the industry tests. However, in the video they show a slight angle is enough to change those results completely. This was true both at, above, and below the industry height standard. Given that you can't be guaranteed of the angle at which a pistol might fall, I don't think this slight modification to the test is completely out of line.
Make some extra. I'd prefer mine with some bbq sauce, if it's not too much trouble.
Well that goes without saying of course. Given the size of the crows in my neighborhood there should be enough to go around.