I don't carry a gun for PD but I do keep them in my house and on my sailboat. Seems to me the only way to get a one-shot-stop with any kind of reliability is to target the head or the spine. That's one reason I have alway prefered big heavy bullets in .44 or .45. Anything is usefull for head shots, but to grab the spine on the way out of some fat bastard you'll need a lot of giddy-up. Small bore magnums and jazzed-up 9mm rounds in the auto pistols like the Super and Sig .357 are probably good enough to get through but have horrific muzzle blast. And you won't be wearing ear protection in a self defence shooting. I'll stay with the relatively low pressure .45acp/.45 Colt class of gun and shoot for bone if the time comes.
Ask any hunter who has shot a bunch of big game about how long it can take many animals to die after being hit perfectly in the lungs/heart with a rifle round that dwarfs anything you'ld want to shoot in a handgun. Some die on the spot but most run for 10 seconds and sometimes much longer. Ten seconds is a long time. Now ask those same hunters how their spine-shot animals reacted. The vast majority can't get to the ground fast enough.
John
Ask any hunter who has shot a bunch of big game about how long it can take many animals to die after being hit perfectly in the lungs/heart with a rifle round that dwarfs anything you'ld want to shoot in a handgun. Some die on the spot but most run for 10 seconds and sometimes much longer. Ten seconds is a long time. Now ask those same hunters how their spine-shot animals reacted. The vast majority can't get to the ground fast enough.
John