If the concern is simply having a gun, which upon presentation of which many self defense scenarios end with the criminal beating feet, then certainly the .22lr works. In any situation it is far better than throwing rocks.
If the attacker and situation do not allow for the presentation of the weapon to have a chance to deter the crime then we need to bank on its effectiveness.
Many criminal will run at the first shot fired, many will give up upon being shot, enough to be concerned about though do not simply decide to give up or run off even when shot. At that point the goal is make certain the threat is ended as quickly as possible without the "agreement" of the attacker.
To "force" the attacker to stop being a threat they must have their CNS shut down, their skeletal structure wrecked to the point at which it cannot support them so you can get away, or they must loose enough blood so that they can no longer operate.
1. Damaging the CNS. To do this you need to punch through the skull or penetrate through the torso and its bone structure to make your way through a vertebrae. Sorry, compared to other calibers the .22lr is woefully underpowered for the task of reliably punching through the curved surface of the skull or making it through the torso to crack the vertebrae and sever the chord. All handgun calibers are a compromise but in this case I cannot see the compromise as reasonable. (You could get lucky and shoot through the neck's vertebrae...)
2. Shattering Supporting Bones. Often hoped for with a pelvic shot every handgun has serious problems doing this, the .22lr being the worst of the bunch.
3. Blood Loss. All things being equal this comes down to depth of penetration and expansion. In short, wound cavity. Sorry, that .22lr will not make anywhere near the cavity of an expanding .38, 9mm, 45, 10mm, even a .380. Therefore bleeding out will take longer and the fight will go on. He may still die or collapse but it will take longer and he will still be a threat in that time.
Sorry, the success of the .22LR as a defensive round depends on the will of the attacker. It depends on him giving up. Should he give up it has worked as well as a .44 mag. Should he not give up you are now stuck dealing with all the round's shortcomings. Hopefully he gives up.
If the attacker and situation do not allow for the presentation of the weapon to have a chance to deter the crime then we need to bank on its effectiveness.
Many criminal will run at the first shot fired, many will give up upon being shot, enough to be concerned about though do not simply decide to give up or run off even when shot. At that point the goal is make certain the threat is ended as quickly as possible without the "agreement" of the attacker.
To "force" the attacker to stop being a threat they must have their CNS shut down, their skeletal structure wrecked to the point at which it cannot support them so you can get away, or they must loose enough blood so that they can no longer operate.
1. Damaging the CNS. To do this you need to punch through the skull or penetrate through the torso and its bone structure to make your way through a vertebrae. Sorry, compared to other calibers the .22lr is woefully underpowered for the task of reliably punching through the curved surface of the skull or making it through the torso to crack the vertebrae and sever the chord. All handgun calibers are a compromise but in this case I cannot see the compromise as reasonable. (You could get lucky and shoot through the neck's vertebrae...)
2. Shattering Supporting Bones. Often hoped for with a pelvic shot every handgun has serious problems doing this, the .22lr being the worst of the bunch.
3. Blood Loss. All things being equal this comes down to depth of penetration and expansion. In short, wound cavity. Sorry, that .22lr will not make anywhere near the cavity of an expanding .38, 9mm, 45, 10mm, even a .380. Therefore bleeding out will take longer and the fight will go on. He may still die or collapse but it will take longer and he will still be a threat in that time.
Sorry, the success of the .22LR as a defensive round depends on the will of the attacker. It depends on him giving up. Should he give up it has worked as well as a .44 mag. Should he not give up you are now stuck dealing with all the round's shortcomings. Hopefully he gives up.