Over at Stopping Power, you’ll note that Marshall never says there’s a magic hullet or load.
The same was said in the books.

There are many factors in play.
The statistics had to be broad and general and couldn’t factor ib things like attitude or the will to live.
Some results had transposed numbers, some just had the normal flukes.

However around the same time, a couple of other studies were done, with similar results and different data sources that got similar results.
Then there’s info from sources like Cirillo who got to see firsthand the results of numerous gunfights including his own. As well as ER doctors reports up to the present.

In the end they all generally come to the same conclusion, with modern ammo and decent hits there’s little difference between the common defensive chamberings in effectiveness.

Choose the biggest caliber and weapon you can effectively use and you’re generally well off, providing you used good ammo.