The original 1911 design is drop safe with the original spec firing pin *if* the cartridges it’s loaded with have military spec primers. The pin doesn’t have the mass or inertia to successfully detonate a military primer. Mil-spec primers are usually thicker-walled, made of a harder alloy and sometimes even domed/concave - they require a much higher energy than commercial primers to set off.
Commercial/civilian primers do not have to pass such testing and are much easier to set off. Depending on how ‘soft’ the civilian primer is, the 1911’s original weight/spec inertial firing pin can actually set it off in a muzzle drop.
Thanks for all