The potential one stop shot doesn't exist, and the existence of the .45ACP was to prove it would still be only an incremental improvement. That means the percentage of shots needs to stop only decreased slightly.
It could be said the officer using an AR pistol in .300BO wouldn't have gotten any better results. And the list of failure to stop would keep escalating right up to those xrays of humans with unexploded mortar rounds imbedded in their body being prepped for surgery.
The use of drugs only makes it worse, and even if you do hit the heart, it still takes from 30-90 seconds before the brain begins to feel the effect of a loss of blood circulation. As anyone who's contested with their siblings knows, you can only hold your breath for so long, but trained divers can go 4-5 minutes.
Center of Mass shots do a credible job of slowing down or stopping humans, a central nervous system hit does it much more quickly. It immediately interferes with control over parts of the body if not completely. Hence the last few shots being head shots, and the officer recognizes they are much harder to make, therefore he braced against the nearest object to steady his aim. He was, after all, using a handgun with an effective range measured in feet - not hundreds of yards. Handguns are extremely portable but not the most effective tool in stopping humans. They are seriously compromised and not the best choice - which is why every army in the world issues RIFLES and the dominant casualty producer overall has been artillery or air dropped munitions. Small arms projectiles are by and large restricted to that short range where the crew served munitions effective kill zone overlaps the ground that your own troops occupy.
It might be an older shooting, but it is a good illustration of what a handgun will and will not do. Those shots taken initially failed to stop, the last few were precisely aimed with a steady rest. And as usual in real life, the target refused to stand still in the open, unlike most range exercises where safety is promoted over tactical excellence due to a lack of resources or imagination.
I made the comment quoted above, I'm a fan of Mas Ayoob, but the point of my comment was the unstated slant that a handgun in the hands of a competent shooter should have done more, sooner. There is no guarantee of that, ever. It is indicative of human nature that the number of rounds previously carried is now considered inadequate, when the reality is that it always will be. There can be circumstances where even if the individual carried 300 rounds it wouldn't be enough. You have to assess what your level of risk is and also deal with the after shooting reaction that your incident slipped into that small minority of shootings we tend to focus on.
