.22 Long Rifle for Self Defense
I am against .22 ammo for self defense for several reasons. It's incapacitation record is low. The .22 is on record as having caused more deaths than any other caliber. The deaths all to often occur long after the gun was fired, and the statistics are skewed by the sheer volume of .22 caliber weapons in existence however. Most of these deaths are due to accidents, not attacks. The argument for "a faceful of .22" holds just as true as the argument for a faceful of .40S&W.
What is lost on many novices is the actual dynamics of self defense. With a .22 pistol, it would take seven well aimed shots to inject the same lead volume of one bullet of .45ACP. Those seven shots take time, and the cumulative effect may not be reached until minutes or even hours later. People have been shot in the face with a .22 and lived. While you are squeezing off your second and third shot, your attacker will not be just standing there waiting for more. They will be continuing the attack, or making it a lot more difficult to shoot them again.
Before a jury, seven shots to the face with a 22 caliber weapon has a much greater impact than one shot to the face with a 45. When one must defend their actions in a court of law, the number of shots often hold great significance with jury members who do not understand the dynamics of self defense. To a jury, seven shots of anything to the face is horrible overkill. One 12 gauge blast to center mass with a duck gun is restraint. Never mind the ballistics or other facts involved, it's the impression the attorneys are able to exploit and the jury develops that affects the verdict. To survive a lethal encounter intact, a person must also survive the legal entanglements afterwards.
The first shot in a gunfight is often the defining shot of a gunfight. When that shot is made in self defense, it needs to have maximum impact on the aggressor. That is why I advocate the 12 gauge shotgun for the home and the .45ACP or .40S&W for carry. None of my preferred self defense weapons force the defender to shoot the attacker in the face multiple times to increase the chances of survival. All have the capability of stopping an attacker with a center of mass shot. Of course, as shown in the George Temple incident, multiple COM hits of .45ACP may not be enough. There are many articles written by men more knowledgeable than I on the various aspects of ammo and caliber selection. I will defer to their expertise when it comes to muzzle energy and other variables such as Relative Incapacitation Index.
.22 Long Rifle ammunition is notorious for it's inconsistency in ignition, as is any rimfire cartridge. This inconsistency in ignition is as unacceptable in a defensive gun as having tires that may not stay inflated on your car. When a life is on the line, any history of ammunition failure is unacceptable.
All guns depend on one variable for stopping a determined attacker. That variable is user input, the willingness to use the weapon and the capability the shooter possesses for hitting their target. If the defender refuses to shoot, or is a poor marksman, a grenade launcher will not have any impact. The .22 handgun is better than a pointy stick if one needs a tool to defend one's life. A larger caliber is better than the .22 though. The .22 pistol is a fantastic tool to get acquainted with firearms and learn marksmanship with. The Ruger MKII and Browning Buckmark are accurate, and inexpensive to buy and shoot. That allows a person to shoot them a lot. The volume of shooting with an accurate, low recoil gun is what allows a person to develop into a superior marksman the fastest. At least that is what I have seen.