I agree with the original poster. Shot placement is almost everything, provided that penetrastion is sufficent to get to whatever vital organs are being aimed at.
The problem with police and ccw training is the center mass shot. There isn't anything imediately lethal there. Heart shots should be placed much closer to a shirt pocket, but how many times will a threating person present himself the same way a sillouette target does on the range? Probably never.
This is why i carry a .44 magnum. All the penetration you could need, even with the slightly reduced loads I carry, and plenty of precision in a big heavy "N " frame Smith. Good trigger job, good sights, points well, almost always gets grasped right by the hand while in the holster, what is not to like? Recoil? Figure the recoil of a GLOCK 22 or 23 with some really effective .40 S& W loads, and get back to me.
I see two real problems with weapons and tactics today. The first is trying to turn a weapon into something comfortable to carry. Big, big mistake. It ought to be comfortable to shoot. Carrying a weapon, any weapon, is a pita. Learn to live with it. Second, training is lacking in reality. YOu must aim , yes, I said aim, for a vital structure. If pistols and revolvers were meant to be pointed, they would have a bead front sight like a shotgun.
Insofar as caliber, I could give a rip. What is important is penetration. A 30 lugaer will shoot through most anything a man might encaounter. Selous, wdm bell and other took quite a few elephants with 6.5 and 7mm rifles, with heavy for the caliber bullets at around 22-2300 feet per second. What they had in common was a bullet that would stay together, penetrate to the vital structure, and were capable of being aimed precisely. There is nothing wrong with a .38 special, provided that the bullets selected will penetrate. This means semiwadcutters, or flat points. (mm is entirely unsuitable, not because of caliber, but because it lacks bullet weight and shaspe. Feed it a heavy147 grain or more swc, and you will see business pick up. Same with a 40 or ten mm. The magnums are the best, but it is mainly because of bullet weight, accuracy, and bullet shape.
If we are to survive a gunfight, we need a bullet that will reach the vitals from most any angle, and training that will teach ust to aim, yes I said aim, for a vital structure. A marginal hit from any caliber is not going to do the business. A .22 is great for slaughtering hogs, but if you go hog hunting, you want a 41 or 44 magnum. Why? It is very hard to hit them between the eyes at the distances they are generally engaged at. You still need to practice until you can hit the heart, or get a double lung shot. Why is it any different with self defense? Any thinking person knows it is not.