IIRC, those discharge were because the default trigger was heavy, as in its mass not trigger pull, and, if you dropped it at a certain angle, the inertia of the trigger would pull the trigger. The fix was Sig doing a free upgrade to a lighter trigger that wouldn’t have a much mass.
AR 15 drop in auto sear using an index card as in you fold a piece of paper a certain way and put it in your rifle it will cause it to shoot full auto. You don’t really want full auto anyway, just wasting ammo really.