Many semi-auto .22s have tube magazines. Slow to reload but hold up to 20 rounds. Dale also related a story about a perp who got shot above the knee and died. Could have happened if the femoral artery were cut.. but he said the bullet ricocheted off of the femur and went up into the abdomen ripping through vital organs. So... .22 semi rifle with mag loads??
I wouldn't want to get shot with one and of course the bullet is the same diameter as a 5.56 AR round. Still, if I can choose, I want something more powerful. A .410 shotgun is certainly lethal at close range too, but why not go to at least a 20 gauge? There has been a lot of debate about the most effective pistol cartridge. For a long time, everyone said a 230 grain .45 cal. Now I see arguments backed by data saying 9 mill and .40 are pretty much as effective. Corbon makes a copper .45 round that is 185 grains and is said by some to be the ultimate stopper. Or you could get Desert Eagle in .50, but don't count on hearing again after firing it indoors with no ear protection. Followup shots will be slow as well. With rifles, the 5.56 has always had a reputation as lacking stopping power. I know Lucrum favors .308, which will definitely do the job, no questions asked. I worry about over penetration though. Of course, 5.56 has no penetration, which can also be a problem. If you are barricaded inside your bedroom and someone is breaking in the door or firing through it at you, you are not going to be able to shoot them through the door with a 5.56 round. A .45 will go through it like it's kleenex though.
This would be sort of a fun home defense .22. <iframe width="420" height="315" src="http://www.youtube.com/embed/QS31Gm9tIig" frameborder="0" allowfullscreen></iframe>
I don't consider my .308 as home protection, except maybe during a riot. My primary is a sawed off 12 ga pump with a pistol grip and of course my .45 with laser pointer embedded in the grip. Just point and shoot.