Shoot them in the head. Problem solved."just kidding" My good friend had to shoot a 400+ lb woman while resonding to a domestic dispute in Harlem about 25 yrs ago. She ran at him with a foot long butcher knife. It tooK a full cylinder to put her down. Her forwad motion was like a freight train, and he surelly would have been dead if she had reached him. Now that was a lot less than 21 feet, maybe 12-15, and he moved laterally as she tansversed the kitcken, "which slowed her down, but he almost died that day, just checking on screaming that a neighboor caled in, "she had burned her kids hand on the stove, as punishment". So that is one time when accurate constant firing stopped a cop from getting killed. The knife thing is quite true.He was cleared of any wrong doing but spent 6 -9 months on a desk anyway, mainly because it was a black woman shot by a white cop.I don't remember if he went to his backup gun, I believe the revolvers were still in use then.
I know his parntner didn't fire, because it was such a small area and there were kids there also. If you remember the incident the guy went on to make detective first grade down the road, and he was the youngest ever at the time, his last name was De'Stefano, and a dear friend of mine, who had nightmares over this for years.He later worked th 72 and 77 in Brooklyn later on, in Robbery/Homicide.