Early Colt Pistols dropped for test
First, an "accidental discharge is caused by a part failing and the weapon firing, such as happens with a loaded and locked Luger when the projections on the firing pin shear from fatigue and the gun discharges. "Unintentional Discharges are caused by human error.
I have made personal drop tests, with a mechanical engineer from two different heights. In 1,000 drops from the height of a Chevy Blazer, as would happen if your pistol fell to a hard surface as you got out only four drops resulted in a hit squarely on the muzzle. All four resulted in a faint primer dent.
1,000 drops from a tall ladder to a gravel driveway resulted in onoly one hit directly on the muzzle and another light firing pin dent in the primer. A slightly heavier firing pin spring would have negated the denting of primers.
FIguring it out using the law of physics, it requires a direct hit on the muzzle from five stories to cause ignition with a standard, (worn out) G.I. firing pin spring.
Mostly, air pressure will prevent the pistol falling muzzle first, and proper maintenance will take care of the rest.
All of the U.S. Services have carried 1911 pistols for most of the 20th century. To date, I have been unable to find a case history of a dropped pistol firing. Several who claimed this happened were proved to have been caused by other circumstances.
I know of only one authenticated case under very unusual circumstances, where a hunter threw a loaded, locked 1911 at a "rat" in the corner of a log cabin resulting in a fired shot. The pistol was mine, but the thrower was not yrs truly. The "rat" was a terrified little squirrel and the firing pin spring was installed in the pistol by the COlt factory in 1917; the incident happened in 1993. The pistol was thrown end over end, hit squarely on the HAMMER. Evidently, rebound from the firing pin stop was sufficient to propel the firing pin hard enough to ignite the round.
Since I was not present, I cannot vouch for the veracity of the facts, and I have no idea what role Jack Daniels played in this.
If I wanted to, I could perform a set of drop tests with the notion that "I'm gonna make this sonofagun fire" and probably get ignition, but all lyou have to do is drop your old .45 1000 times from 15 feet to see that the Navy test was flawed. ANy test, to be believable, must be duplicated at will with identical results. Try it yourself.