There are many excellent cartridges for concealed-carry purposes, and few people argue with the effectiveness of the 9mm Luger, .45 ACP, or .357 Magnum, just to name a few.
However, if you want to start a heated debate, ask two concealed-carry proponents about the viability of .22-caliber firearms; you’ll likely get two vastly different opinions about these small, lightweight weapons.
Advantages of .22-Caliber Cartridges for Concealed Carry
There are two distinct advantages for .22-caliber handguns. The first is that the recoil is virtually non-existent. For smaller, weaker people, the kick of a powerful cartridge can be intimidating, but a lighter .22 LR or .22 Short cartridge is much easier to use, and the light recoil can bring more accurate follow-up shots, which can be crucial in self-defense.
The other issue is that .22-caliber handguns tend to be smaller. Because the cartridges are smaller, the handgun will be able to carry more rounds while needing less space, bringing greater concealment.
Disadvantages of .22-Caliber Cartridges for Concealed Carry
The major disadvantage, and the reason the .22 is downright laughed at by some firearms users, is that it is not nearly as powerful as other cartridges. Even the .22 LR has limits on stopping power, and many people feel that it is insufficient for stopping a threat.
An interesting study from Greg Ellifritz of American Handgunner found that while .22-caliber cartridges stopped 60% of threats after one shot, they did not stop 31% of threats. Interestingly, the .45 ACP, for example, stopped only 51% of threats after one shot, but only 14% of all threats not stopped.
This is only one study, but it does imply that .22-caliber firearms may not be enough to stop an oncoming, motivated attacker. A 31% chance of the threat not being stopped at all seems far too much.
If you feel more comfortable with .22-caliber handguns, then by all means that should be the weapon you carry. Just be aware of the potential limits in stopping power.