The standard of a defensive caliber is that it needs to be capable of immediately halting an attacker with the kinds of shots a scared defendant can pull off[0]. Not killing them immediately or eventually, but halting the attack. Plenty of gun shot wounds are capable of killing eventually even if they’re not immediately disabling, and it does you no good if your assailant eventually bleeds to death after they’ve finished stabbing you.
The issue is that halting an attack occurs because of hydrostatic shock, which is a product of a bullets velocity and expansion. 22lr is capable of causing blood loss, which can eventually lead to death, but it does not deliver enough energy to reliable render an attacker incapable of continuing the fight if they’re sufficiently motivated. Assuming that the assailant isn’t immediately scared off by the brandishing or noise of a firearm, which is often the case, 22lr requires extremely good shot placement and volume to reliably end a fight, which makes it a poor choice all around.
Generally for modern firearms the minimum is either 380acp or 9mm, depending on who you ask. The only advantage that 380 has is that some 380 guns are easier to manipulate for those with weak or small hands, otherwise 9mm is generally the winner here in terms of firearm choices, ammunition availability, and terminal ballistics.
For comparison, here are the levels of energy for 3 cartridges. Energy isn’t the be all end all of terminal ballistics, bullet construction[1] and expansion matters, but it’s illustrative. The ranges quoted are necessary due to different bullet weights and pressure loading.
22lr: 130-200fpe
380ACP: 210-330fpe
9mm: 355-500fpe
0 - Any caliber is capable of killing and/or disabling with luck or extremely good shot placement, this is why even 22lr cannot be treated as a toy. But people shooting defensively do not make record shots generally, and you have to accommodate for the fear and adrenaline of a defensive encounter.
1 - The availability of quality defensive ammunition is another big factor. Defensive ammunition has gotten really good over the past half century, and most of these improvements have completely bypassed 22lr.
Thank you for the detailed response.
I guess my dreamed up scenarios were more vague "shooter/assailant in the area" whereby I figured I'd want to "make myself less desirable to bother with". Hence small caliber, lots of noise/attempts and if - god forbid - anything connected it would still hurt/slow them.
I never really contemplated a "someone intent on killing you" scenario. It isn't something I think of much and I appreciate that clearly people have.
From your comments it seems clear that "stopping power" holds more of a place in conversations.
It is interesting that 22lr hasn't really been technologically updated. But I guess there would be interoperability issues and a "chicken(gun) and the egg(ammo)" scenario to overcome from a commercial point of view.
> I guess my dreamed up scenarios were more vague "shooter/assailant in the area" whereby I figured I'd want to "make myself less desirable to bother with".
Generally the rule on such matters is that there is no such thing as a warning shot, both ethically and legally. For the same reason that shooting for the legs is a bad idea, bringing a lower caliber firearm to warn someone off is kind of a no-no. You should either be shooting to end the engagement, or not shooting at all.
Obviously retreating from an encounter is always the best course of action (and a legal obligation in some states) if possible.
> It is interesting that 22lr hasn't really been technologically updated.
22lr has seen tons of advancement, just not as much in the realm of terminal ballistics. There is incredibly intense competition for more accurate and consistent 22lr ammo, as this is the caliber used for a lot of olympic shooting and some increasingly popular non-olympic competitions.
Fundamentally, it's really not possible to squeeze much more energy out of 22lr. Every production cartridge has a set maximum pressure and firearms are certified for this pressure by nation specific proof houses. For 22lr the max pressure is about 72% the pressure of a 9mm[0]. Squeezing more terminal power out of this cartridge would risk catastrophic firearm damage and probably company liability.
Making matters worse is the fact that semi-automatic (e.g. handgun) firearm design changes pretty radically around or above 380ACP pressures. Above that firearms must have some sort of mechanism to delay opening until chamber pressures fall to a safe level, otherwise cartridges will potentially rupture during extraction and hurt the shooter. All 22lr pistols are of a much simpler design that improves accuracy and lowers price, but makes getting 9mm pressures into an existing 22lr handgun an impossible task. Much easier still to just start with a 9mm, since those work and are well understood.
Also, it's a rimfire cartridge, and that's undesirable for a variety of reasons I'm too tired to explain right now.
It has been technologically updated -- they do improve the tolerances and consistency, introduce wear reducing coatings, and stuff like that -- but it is fundamentally a small, light bullet in a tiny case. That's what defines it, so there's just not much more power you can get out of it.
> I guess my dreamed up scenarios were more vague "shooter/assailant in the area" whereby I figured I'd want to "make myself less desirable to bother with". Hence small caliber, lots of noise/attempts and if - god forbid - anything connected it would still hurt/slow them.
This constitutes the crime of brandishing. You should not own any weapons if you can't keep from fantasizing committing crimes with them.
The issue is that halting an attack occurs because of hydrostatic shock, which is a product of a bullets velocity and expansion. 22lr is capable of causing blood loss, which can eventually lead to death, but it does not deliver enough energy to reliable render an attacker incapable of continuing the fight if they’re sufficiently motivated. Assuming that the assailant isn’t immediately scared off by the brandishing or noise of a firearm, which is often the case, 22lr requires extremely good shot placement and volume to reliably end a fight, which makes it a poor choice all around.
Generally for modern firearms the minimum is either 380acp or 9mm, depending on who you ask. The only advantage that 380 has is that some 380 guns are easier to manipulate for those with weak or small hands, otherwise 9mm is generally the winner here in terms of firearm choices, ammunition availability, and terminal ballistics.
For comparison, here are the levels of energy for 3 cartridges. Energy isn’t the be all end all of terminal ballistics, bullet construction[1] and expansion matters, but it’s illustrative. The ranges quoted are necessary due to different bullet weights and pressure loading.
22lr: 130-200fpe
380ACP: 210-330fpe
9mm: 355-500fpe
0 - Any caliber is capable of killing and/or disabling with luck or extremely good shot placement, this is why even 22lr cannot be treated as a toy. But people shooting defensively do not make record shots generally, and you have to accommodate for the fear and adrenaline of a defensive encounter.
1 - The availability of quality defensive ammunition is another big factor. Defensive ammunition has gotten really good over the past half century, and most of these improvements have completely bypassed 22lr.