We did something like this a couple years ago with our Tri-State shooters here in Memphis (where's PEC-Memphis...). As I recall, the general results were similar, with empty chambers taking longer to complete stages. A couple of things we should look at additionally, are: time to first shot and accuracy. Harder to test is: these were all shooters who were knew the course of fire and knew the beep was coming. It'd be interesting to see how the element of surprise would impact the results, especially if you can get inside the OODA loop earlier, for example, going hands on before engagement.
Good job in pulling all the data together. It still tells me that when seconds count, I don't want to be jacking the slide back while staring at the threat.
-The only easy day was yesterday
-If you are authorized to carry a weapon, and you walk outside without it, just say this to yourself... “Baa.”