Since you can’t get what every hunter or surgeon understands about energy transfer to tissue let us try another approach.
Several years ago I spent a few years shooting in handgun competition so I have a little familiarity for training for combat handgunning. In this case of Twin Peaks shooting almost everyone that was struck by a bullet was killed outright. I recall reading of one victim who still retains a bullet or a fragment and there may have been some that we’re transported to hospital but the majority went straight to the morgue.
For your opinion to correlate with fact two things need to be true. One, that amateur hand gunners would shoot for the brainstem as a primary target. Two, they were justified in doing so as evidenced by the superbly inerrant marksmanship they accomplished. Find any, and I mean ANY instructor who teaches combat hand gunners of ANY level of experience that teaches people to place their first shot in the brainstem and I will yield. In spite of the fact that you claim a parking lot full of hooligans did, indeed, accomplish this miraculous feat of handgunning excellence. Sorry, no way.
Are you discounting the eyewitness accounts?
While they are on the ground wrestling, a different Cossack approached, kicks Mohawk in the head, pulls out a gun, and shoots Mohawk in the face (killing him).
http://www.copblock.org/157467/waco-twin-peaks-biker-shooting-video-witness-statement/