***A bullet dropped from 30,000 feet will reach terminal velocity and may or may not be deadly.***
Years ago I read about small metal darts that were dropped on infantry in WWII. Hardened heads were supposed to be more effective than strafing. Ever so often I would see these darts at a gun show.
I got a call this year from Texas in which a 50 cal FMJ bullet hit a double pained window, broke the outer glass then dropped to the sill. It did not break the inner glass. I figure someone far, far, away fired it. The owner was so glad no one was targeting him!
I sure wouldn't want to get hit by a falling bullet.