Once that round leaves the device used to fire it, and lands in or about its intended target..... what happens to it after that is outside of any human control.
As to the comment about cops themselves succumbing to testosterone and adrenaline and being dicks.... Well. Yes it does upon occasion happen.
Thats what happens when you have humans doing the job.
ALL human beings are subject to making wrong decisions, decisions made in anger, acting on emotion, or just plain mistakes in judgement, motor control (missing an intended target). However, not all humans are held to the standards that police officers are held to.