There are plenty of examples where attackers have taken many, and I do mean many, hits in the chest (COM) and still stood. What is more, if you have a limited capacity weapon, say revolver or single stack auto, you can run out off ammo very quickly.
And keep in mind while you are machineguning your attacker, if he has friends they will have time to repay you (or even the one you are shooting will have time to repay you.)
http://seattletimes.nwsource.com/html/localnews/2010572291_shootingmain23m.html
Here police shoot man multiple times yet he returns fire.
"Just before the shooting, Troyer said, David Crable
appeared intoxicated but was cooperative and had agreed to leave the home with the deputies. But then he pulled out a handgun hidden in a shirt that was tucked under his arm and opened fire at almost point-blank range. Mundell, Troyer said, was shot several times but managed to return fire.
He then was shot multiple times again before Crable collapsed, Troyer said"
And here is another:
http://www.co.washington.or.us/sheriff/media/shttual6.htm
"The suspect turned around and started running back toward the apartments. At that time a Washington County Sheriff's deputy arrived on scene. The deputy parked his car on Tualatin Road and as he was exiting his vehicle he saw the suspect running toward him. The deputy gave the suspect commands to stop, but the suspect did not comply.
As the suspect / threat approached the deputy’s marked patrol vehicle, he was again shot with a Taser, which had no effect on the suspect. The threat continued toward the deputy’s car, opened the driver side door, and leaned into the patrol car and reached for the MP-5 rifle mounted between the seats.
The deputy reasonably believed that the threat would gain access to the rifle,
so he shot the suspect with his duty pistol multiple times with at a least one of the rounds striking the threat.
The threat, after being shot,
came back out of the vehicle and hesitated for a brief moment before again entering the police car, moving towards the police MP-5 rifle. The deputy again shot the suspect with his duty weapon. The suspect again got back out of the car, hesitated for a moment before he collapsed to the ground. The suspect was pronounced dead at the scene. The woman, daughter, and law enforcement personnel involved are safe and the woman received minor injuries from the initial attack."
And earlier in the article he had been shot with another Taser! Now what if he had been carry a gun?
And that's just one google search. There are many on record where cops had to shoot someone quite a bit to get them to stop.
And this is why the CNS shot is a vaild method. Might even be the only real option to stop a determined attacker on drugs or booze or just plain nuts.
Deaf