Lewis and Clark's airgun took 1500 strokes to pressurize. It was in service with the Austrian Army, so built for military use (in other words, tough).
https://en.wikipedia.org/wiki/Girandoni_air_rifle
To me, first define what is meant by "Survival". Is this a total breakdown of all government and most of the people are dead, so all we are doing is trying to catch some birds, or is this a situation where you are just camping and want some fresh meat for dinner?
If total breakdown (Complete SHTF), forget the air rifle, get something that can defend against other people. Store lots and lots of ammunition. Think of an air rifle as a way to practice for the Zombie Apocalypse, but do use the Powder Burner for the apocalypse.
If it's for camping, to me the gun should be completely self contained, with the fewest moving parts possible. Probably a .22 beak barrel would be best to me. A .177 too small, a .25 ammunition is too hard to find. A .22 is a good combination to take rabbits and other small game. PCP's, while I love mine, too many things required to support the gun. Tanks, pumps, and such. The PCP just has too many failure points.
Single Stroke Pneumatic type guns would be fine as well, as they are self contained. Same with pumpers.
The Break Barrel to me though seems to make the best choice.
1. the guns are completely self contained
2. Ammunition is plentiful at Walmart, and other places
3. They are typically tough, and reliable
4. probably the lest expensive if you plan to store it. You cam buy a couple and have a couple backups, or give the backups to other hunters in the party.
Just my opinion, though must say I'd love to have a Girandoni in my collection. Better yet, a replica that could be fired without worrying about the brittle air tanks. Just think, a 30 shot, .46 caliber PCP that you only need to pump to about 800 PSI. That was a nice gun.
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