Just joined so I've not been reading much of anything but just did read Ayoob's recommendation for the .308. Nothing wrong with the caliber. I shoot and load for guns ranging from the .22/250 to the .375 H&H Mag. But my choice for SHTF is the .22 Long Rifle. Why? Because ammo is plentiful, doesn't weigh much and will be effective in a variety of weapons. No, not my ONLY choice, just the principal one. Because it is compact, convenient, ammo is plentiful. The caliber can be lethal with careful shot placement and nobody will disagree that being hit by the .22 LR is not a pleasant experience. Okay, it certainly won't stop an automobile much less a charging rhino. But, as Ayoob says in his article, much depends on the nature of the "S" and the "F". The problem is that whatever might happen won't necessarily play into your personal plans. If the "S" is an atomic missile from North Korea (or any other place) that hits a big city near where you live, and you survive but have to manage the problems, there isn't much time to select whatever you might need if you have to get out of town. What if the attack comes to another city far away and you are not threatened? May not have to do anything. Look at the movies that show different scenarios. They are fiction but reflect many of the possibilities. Will the emergency last a long time or just a week or less? Do you have to set up a complete living program/residence in the woods somewhere, live in a crowded condition within a city? All are possibilities...but a .22 LR will be useful in just about anything. A long rifle barrel, a shotgun, even a heavy pistol can be a handicap. A significant economic collapse or a political catastrophe where the new government decrees martial law? Anything is possible.