I carried a Phoenix Arms .22lr for years and only had to pull it once in all that time. Perp peed himself at the sight of a gun barrel, so I didn';t have to shoot, but the aim was directly at his head at thirty feet, so he probably had no idea the caliber. At that range I had practice hitting eye-socket sized targets and would have dropped him instantly since I had cocked the hammer on the single action cycle. That is one reason I like the Ruger SR22 so much; it is double action so I can load the firing chamber and have only to pull the trigger ... and it is very reliable and deadly in .22lr caliber.
If I'm carrying the Bersa 9mmUC Pro I would probably put one or two rounds in the lower pelvis and then one to the brain pan if I had to pull it. Nice pistol. I carry a courrier's pouch all the time outside the home, so I can pretty much haul around anything I want to load up. The Bersa UC Prohas greater capacity than the CZ82 making it just a smidgen more preferred, but not by much. BTW, a Bond Arms in 9mm with three inch barrel might make a nice back-up, too. Wouldn't go below a 9mm in two shot derringer though ...
That's sound advice in any self defense firearm. It's what I teach under 99% of circumstances. Some exceptions are notably, my wife who was a great shot with her 45 Commander until six years ago when she got a very aggressive form of breast cancer which she thankfully survived but left her severely weakened for probably the rest of her life and so she can in no way tolerate the recoil of a serious handgun. So I got her a Kel-Tec PMR 30 in .22WMR with three 30 rd magazines. She prefers not to use it and I understand. Anywhere she might need one, I'm there and carrying. She knows how to chamber, load and fire everything in my possession, so if there is an emergency, she will acquit herself well, I know. She is after all, besides being my wonderful bride of 27 years, the daughter of a US Marine Colonel and a hero of WWII (R.I.P).
I have an elderly and very wealthy client whom I taught to shoot for his CCW permit. I've been working with him for months. He doesn't want to wear a holster and lug around a weight. He's got some serious health issues. To top it off he has the most extreme case of recoil sensitivity I have ever seen and he had it before he came to me. I start everybody and I mean EVERYBODY on a .22 revolver. (I don't care if you're a SEAL) -- if you take my CCW class you'll do a cylinder of 22LR from a S.A. Ruger before we go any further. This guy is dedicated to his own security. He could easily afford a top tier security team if he wanted it, but he want's to be prepared on his own. So we work together when he's in town (he jets around the world tending to his business interests).
At this point he has rented just about every possibility we can find at the local ranges and not liked any of them. I'm torn between the possibility of one of these on the small caliber side and maybe one of these in a 9mm. Problem is the latter is so new I can't find one anywhere, let alone one to rent! Brand new gun there's no track record on self defense yet. I've not seen many reviews, either. So I'm leaning in the direction of the .22WMR, but we'll see.