If you have a very reliable always-shoots pistol and practice, practice, practice short range head shots (10-15’), you don’t need a big caliber, IMO.
Tell that to Merritt Landry. Shot a burglar square in the head with what I’ve been told was a 9mm. The teen suffered brain damage but lived through it. Plenty of cases were bullets don’t make it through some blockheads.
I respectfully disagree. Get a bigger caliber and aim for the hips. The hips present a larger target and almost always the perp will drop like a sack of potatoes when his/her hip gets broken. Placing a head shot while under the kind of stress that one is faced with in such a situation can be extremely difficult, especially at any range outside of 7'.
Long ago I was on a college pistol team, shooting .22 caliber Hi Standard Citations. The real expert shooters could hit a coin-sized target at 50’ all day long. They could probably make head and face shots faster than most shooters could hit center mass with a centerfire. But it does take practice.
In High school a young lady a few grades behind me decided to commit suicide with a 22 pistol. It entered the skull over her right ear, moved forward and bounced off the interior cranium. She lived, her personality changed becoming less shy and depressed, but she was a fully functioning individual with no disabilities.
I’m not saying a .22 can’t be used as a defensive weapon, but I would not use it as my personal go to caliber.
Yep. .22LR is very reliably leathal on humans, pigs, and other large targets if you hit the right spot.