I agree with the FBI (http://www.firearmstactical.com/pdf/fbi-hwfe.pdf). Get a handgun round that can penetrate 12-14 inches. If it has too much recoil for you to shoot well, step down to the best you can find that you CAN shoot well. Then practice.
My home defense gun is a 3” 44 Mag...but with its weight and grip combo, it doesn’t bother me to shoot it as much as my J frame in a hot 357. For carry, I use the J-frame, but with the old 38 special +P “FBI” load.
Oddly enough, the one time I’ve pulled a gun, it was a 22 - all I had at the time. But I had shot 10,000 rounds thru it, wasn’t going to miss, and none of the 8 guys wanted to be first. I think my confidence that I could go for a head shot showed in my body language, and the would be robbers lost interest.
Oh, and it was a 6 shot revolver, so it was physically impossible for me to stop all 8 guys. But as it turned out, I didn’t need to fire a shot...
Also this:
http://www.snubnose.info/docs/No_faith.htm
so you actually got 8 psychological stops with a 6 shot .22...great job...!!!
Dayum, Mr Rogers...things sure have gone to hell in *your* wonderful-day neighborhood.
:)