. 22 for me is top of the list because of the amount of ammo you can carry. If you are in a situation where you have to be on the move, carrying around 100 rounds of anything bigger than a .22 will get challenging. I suppose when I think, preparedness, I think bug out. If I had a place to store my ammo and didn’t have to lug it around then any of the other suggestions made seem plausible. Shotgun would be great, but again think about carrying 100 rounds of 00… 100 rounds of .22 can fit in your pants pocket.