More shooting = better accuracy and becoming comfortable with shooting said gun.
I still shoot .40 cal and have a good bit of quality defense rounds but shooting 9 next to 40 I can immediately tell which one will stop a threat... both.
I can't believe I watched the whole thing but it was well done.
10mm would have incinerated the dummy and knocked the top off of the adjoining mountain down range...
But I digress...
He mentioned training. I think this is the key point. Whatever round they choose they should make the standards tough to meet and retrain as necessary.
But in a government organization, good luck with that last point.