If you believe like I do that all defensive handgun cartridges are under-powered; to choose a .22 magnum rimfire as the tool with which you are going to bet your life seems to increase the risk of failure to stop a threat as quickly as a more powerful/less under-powered cartridge choice.
In a defensive shooting situation time is something you have to consider precious.
You are reacting to a threat.
You are out of time.
You have to defend yourself right now.
The threat is right there.
Even if you deliver two bullets to center of mass, the threat might still continue shooting at you for many seconds more.
NRA Life Member - Orange Gunsite Member - NRA Certified Pistol Instructor
"When plunder becomes a way of life for a group of men living together in society,
they create for themselves in the course of time a legal system that authorizes it and a moral code that justifies it." Frederic Bastiat