The Sig P320, a $700 pistol from a “quality” brand that was adopted as the new military standard issue pistol, would fire if dropped at the wring angle. They didn’t want to have the trigger-safety mechanism that Glock and others use that includes a spring-loaded trigger lock that prevents the trigger from being pulled without something actually inside the trigger guard to pull it.
So if you dropped it at the wrong angle, it had enough inertia that when the gun hit the ground the trigger would keep moving and pull itself.
This was discovered in military trials, so they fixed the flaw (with a lighter trigger that wouldn’t have as much inertia combined with a heavier trigger pull) for the military, but not for the Civilian model.
A viral YouTube video came out showing how it could be reliably fired by dropping it (the video used blanks so they weren’t actually shooting wildly), and they still denied it was a problem until all the gun dealers refused to sell the gun.
They did a recall, but there’s still probably a million affected guns out there.