“the recent FBI study showing the 9mm as the most effective defense round with modern ammo, to reports from police on their inability to differentiate between wounds caused by 9mm HPs and .45 HPs.”
I understand that.
My only point is that handgun hunters who hunt with dogs have a lot different idea of the minimum caliber for taking soft-skinned, human size prey like cougars.
To their telling, several hits with a 9mm will eventually work, but first the cat comes down the tree, mauls the dogs, then runs into the bush and dies over the next hill.
Note, I am not a handgun hunter (illegal in Canada), so all comments about handgun hunting are second hand.
A cougar is similar in size to a leopard, and in Africa they are considered very difficult to hunt (same thing in India, where man eating leopards are considered worse than tigers). The thing about them is this - and I will delete the fact that they are fast, cunning and sharp of tooth and claw. The thing is they have huge lungs, and their blood is significantly more oxygenated than that of a human. Big game hunters (and leopards are considered big game, which is why it's interesting to me that the hunters consider cougar human-equivalents) have shot right through leopard hearts, and the leopard still has enough moxie to finish the charge and mail them. Big game hunters would often wear 'leopard armor' (a metal or heavy leather neck protector) when tracking leopard spoor in the bush, because at close quarters the brain and blood would be sufficiently oxygenated to finish a charge even when the heart was shredded.
What does that have to do with Cougars? Similar sized cat, and more importantly, similarly oxygenated blood that is at a level no human ever alive would have. Which is why the cat can be shot, mess up your dogs, and then run off to die. A bigger bullet can do a better job than a 9mm (same reason people hunting leopards never use pistols), but my point is simply that no cat (even house cats) are a comparison to humans no matter how soft the skin is.
Dogs and boars are another. I've heard about how 'measly' 9mm will at times shatter on their skulls. Thing is their skulls are very different from that of a human, and depending on shot angle the round can be deflected.
Anyway, for most human beings, a pistol of normal barrel length shooting modern hollow points in 9mm, will be more than enough to ensure they give proper attention. As for those few who seem to shrug 9mm bullets (and we are talking HPs and not FMJs, so no Moro Moro tribesmen), they would similarly shrug off .45s (there are interesting stories of people who have soaked up multiple bullet hits, some eventually dying later and others making it, including .45s)
A modern hollow point fired by someone who can hit the broad side of a barn more times than not is 100% effective is virtually every situation.