A 'pebble' falling from several kilometers (without any acceleration except for gravity) will kill you I think. At least that's what I remember my calculation of over a decade ago.
Did you account for air drag, or did you only consider gravitational acceleration?
At that time it would have lost all of its rotation and probably would be just tumbling with added air drag. A parabolic shoot on the other hand.... But still most probably not deadly... if it was so unfortunate to hit someone in the head/eyes/neck. Which is like an extremely small probability in itself. A hit to the body of person with clothes would probably just bounce (not without some moderate impact pain depending on clothes thickness) and not penetrate.
Sigh..we have to get ya'll some more edjumacation..just saying.
Out of the more than 500 shots fired from the test platform only 4 falling bullets struck the platform and one fell in the boat near the platform. One of the bullets striking the platform left a 1/16 inch deep mark in the soft pine board. The bullet struck base first.
Based on the results of these tests it was concluded that the bullet return velocity was about 300 f.p.s. For the 150 gr. bullet this corresponds to an energy of 30 foot pounds. Earlier the Army had determined that, on the average, it required 60 foot pounds of energy to produce a disabling wound. Based on this information, a falling 150 gr. service bullet would not be lethal, although it could produce a serious wound.
https://web.archive.org/web/20080331192517/http://www.loadammo.com/Topics/March01.htmhttps://www.grc.nasa.gov/WWW/K-12/airplane/termv.htmlWe could dive into Stokes Law or Reynolds numbers but I think I will just leave it with this.
I dont know about you but a 1/16 inch dent in my skull sounds pretty painful...if not immediately lethal.
From your own data:
- Most of the bullets did not even hit the platform. (What I said about human pobablation density).
- 4 hit (out of 500), but only ONE left a 1.5mm mark on wood?
So even in that rare case most probably not deadly even if a head hit (surely painful) and, according to your own data: "Based on this information, a falling 150 gr. service bullet
would not be lethal, although it could produce a serious wound"
It would not even penetrate the skull. There is hair, skin, meat, and bones all of which would cushion that 1.5mm dent better than wood. A serious concussion? Maybe. A slight probability of a deadly concussion? Yeah, but very slight indeed.
Anyway, no, I wouldn't want that random "lucky" bullet hitting me right in the middle of my fucking head or, even worse, an eye

In other words an unacceptable risk.