While I understand the desire for a larger caliber and have a 9mm next to my bed, I've never bought into the "smaller calibers aren't enough" argument. For home defense, I'd happily grab my 22 M4 if it was what I could grab. 25 small rounds aimed with better precision are just as good as fewer larger rounds. Statistically speaking, a 22lr has a better one shot incapacitation rate than a 9mm simply because I believe more people can hit on target with it.
Now, I'm not saying a 22lr has the same "traditional" stopping power against all threats (crack addicts for example) but any gun has stopping power in most instances. If an intruder sees a gun wielded in their direction, they flee. What they don't do is stop to ask what caliber you are using so they can evaluate the risk. Reloads are during a gun fight is very rare in police instances and extraordinarily rare in civilian instances. My EDC is a Kimber Micro 380. My friends all carry 12+ round nines in the city. Their thought is they want more rounds just in case. As someone who has gone 57 years without getting in a gun fight, I look at it as I am carrying 8 more rounds than I've ever needed before.
BTW, if you are looking for a home defense shot gun, look at the KelTec KS7 or KSG. Without mods, they can carry 7 or 14 standard rounds and 11 or 22 mini shells. Tremendously fun guns to shoot at the range and perfect for home defense because of their bullpup configuration.
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