“””I’m pretty sure many of the police officers know whether it was a 22LR or a more powerful centerfire rifle round just by the sound.”””
Do cops go through some special “round recognition” training?
Anyone who spends a bit of time around weapons being fired picks up on things that the average person generally wont'. Extra sensitivity is true of any type profession or hobby which entails a lot of familiarity with things - when I was a machinist, I could gauge small items down to a few thousandths by eye and feel.
I listened to the shots being fire on the video that is out there.
Having heard hundreds of thousands of shots from different firearms being fired, having fired a hundred thousand plus rounds myself.
I believe it was a 22 rim fired but then the recording on a I phone can be miss leading.