I agree with much or all above......

The thing you catch in the video, that one guy mentioned being in talks with Law Enforcement and getting real world street results. No doubt, if in war, using FMJ, a larger cal is preferred..........though you cannot get around sacrificing mag capacity. That said, it sounds like the Army might be going to JHP in 9.......

https://www.youtube.com/watch?v=YFFVsARpdVM

Now again, I have always appreciated larger bullets, heavier bullets, in handguns and rifles when it comes to hunting. So back to my college days, I ran a lot of TC Contenders in 7TCU, 6.5TCU, etc. I also preferred 41 and 44 revolvers over 357.

Since then I have dropped deer with 6BR and 243, thru 338/06. They all died, and no doubt - STOPPING the Threat quickly IS the issue with handguns for personal protection. That said, bullet technology truly does seem to be closing the gap.

So, would one be better off with say a 16 rounds of 9mm in a modern quality JHP? Or 8-10 rounds in a 45 or 40?

Good bullets, placed thru vitals works on 2-legged just as they do on deer. Years back I had no interest in 9mm, as the concensus then was lackluster and mixed. Over time, the newer better bullets have made me completely rethink the 9 and it's reputation has grown alot since the better ammo has been issued to PD around the country.

Be well folks, and above all, train for accuracy, with dependable arms and ammo wink