I've been thinking about the practicality of 22lr - even for defense. It is such a useful round - cheap, soft recoil, good distance. It teaches you fine long distance shooting skills out of a rifle - wind compensation, drop, ... generally teaches you ballistics well - if you are to become able to shoot well at a distance.
Handguns... I've seen people who are good with handguns in general make some extraordinarily long shots, consistently, with 22lr. Very impressive!
It's a fun, capable, instructive round.
Self defense - I've pondered that, too. A light shooting gun spitting out a lot of lead would deter most bad guys out there. Heck... just producing a gun would deter most.
I used to scoff at 22lr for defense. I'm swaying ...
More 22lr's are in my future.