Rhetorician, just another word in response to some of the other posts above:
There are folks who aren't fans of the 22 magnum (22WMR) round, and that's fine. To each his own, and they do make some good points that you should consider when deciding whether to get into the .22 j-frame business.
Ammo expense: yes, 22 magnum costs more. Premium ammo like CCI, Speer, and Hornady in hollow-point will run from around 28 to 30 cents a round at best, to 40 to 45 cents a round for top-end, compared to 8 to 10 cents per round for 22LR hollow points. I personally don't mind paying a premium for my self-defense ammo no matter the caliber, and I can always practice mostly with the less expensive stuff (including 22 mag rifle ammo, which works for me as I bought a 22 mag bolt-action Savage to play with!

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Ammo availability: my local LGS stocks 22LR and 22WMR at decent prices, so it hasn't been an issue for me. I also have purchased from Gander Mountain, Cabela's, and several smaller outfits that one can easily find by using one of the ammo-supplier aggregator sites like ammoseek or gunbot, and sometimes you can find some "bargains" comparatively speaking.
Noise and muzzle blast: for me, these are a plus rather than a minus, in the short barrel 22 magnum. Yes, my night vision might be compromised by it, but I figure I'm only two to ten feet away from my target anyway in an SD situation, so that's not really an issue for me.
Performance: yes, the two rounds do have similar performance (except in the SD rounds, since nobody makes a 22LR SD round that will expand out of a short barrel). 'It is what it is."
Fun factor: To me, it's just more fun to shoot 22 magnum than 22 LR. Your mileage may vary.
