Okay Okay, since this topic was broached in a Rabbit trail on the .357 thread, I thought I might as well make a thread for it.
Can a .22LR be a good defense round?
For me the answer is a solid no, let me explain why. (Opinion Only)
First, any round can kill an opponent when placed perfectly, so this is not about that.
Most of the argument for the .22 for defense we read about or have any data on is related to, you get almost no recoil so weak shooters can put X rounds on target, or you have 79 rounds with which to hit your target so... and the FBI stats show that certain .22LR rounds can penetrate deep enough to meet their own gun buying standards (10-12 inches), but in my humble opinion those are outliers.
What are other consideration? Well, when shooting in combat, running and gunning under pressure, putting that tiny round exactly on the X may be harder than you think. Note: I have never tried this with a .22 pistol, I am a GWOT Army guy...
When acting under duress in order to stop an attacker, I dont know that I want to depend on micro precision with a tiny round, hoping that I hit an organ or other incapacitating point, when if I were shooting a 9mm or 10mm or another defense round, one bullet near that area would stop an attacker.
Another thing in the back of my mind is the condition of the attacker. If a person is high on whatever drug, you can stitch them up with rounds but unless you hit an organ that stops life or a bone structure that stops movement, that high person would still get to you, this has been seen all over the world in combat. In this case you could potentially mag dump your .22 on someone who was high and barring that perfect shot you could still get killed.
There is a lot more to this but these are my initial thoughts.