The OP asked about the .22 in a SHTF/EOTW scenario. To repeat and reinforce what many have said, a key element here is sustainability. If (or when) a serious event occurs, it could be months or years before things return to "normal". Even then, there is no telling what new laws, policies or procedures might be enacted to curtail firearms ownership or ammunition availability.
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For the cost of a couple of thousand rounds of "high power" ammo, you can have a multi-generational supply of quality .22 ammo. And you can stock up without attracting unwanted attention.
Be careful with statistics, though. While a .22 may not seem - or be - as "effective" as a larger caliber, that does not mean it is harmless. As with high powered air guns, successful employment requires a different technique - precision placement - regardless of whether you are using rapid or slow aimed fire.
soupbone
I agree with you in some ways, but then I stop and think about what's realistic. I just don't think I'm "that good" that I can survive firing 10,000 round without having someone on the other side getting lucky and hitting me. If my number one goal in any lethal force engagement is to have it end as quickly as possible so I stop being at risk, then I want to be firing a round that has the highest probability of stopping the fight with a single hit, whether it's to the opponent's forearm, calf or thorax. Every second longer that the fight goes on is a second that I'm taking incoming fire and sooner or later the SOB just might get lucky and hit a family member.
Do I still want 10k rounds of .22? Absolutely, because there is no more cost effective way to train, acquire small game, and deal with nuisances on the 'stead. But when there's lead heading my way, I'm sure that a thousand rounds of .308 (or .223) will be a more effective at stopping the fight, so that's my first choice in that situation. If they're behind a tree, I don't care. If they're wearing Level II or Level III body armor, I don't care. If they're jacked up on crank and I hit them in the shoulder, I don't care. The fight is over and my family is safe.