Air rifles are often seen as weak, and not very effective hunting weapons, and while the smaller caliber modern air rifles ( under .25 ) are not great against human targets, they have some merit.
Firstly I’m talking exclusively about single shot spring / gas piston guns.
Air rifle pellets are cheap and light.
Air rifles are relatively cheap – but a cheap .22 rifle is still cheaper, and a good powerful air rifle will be much more expensive.
Pellets can be improvised -much easier than cartridges can be reloaded.
Air rifles are very quiet, when using heavy pellets that keep the rifle under the sound barrier.
Air rifles are generally not controlled, like firearms are.
Air rifles can be dieseled to get near .22 LR power out of them, (this can damage the piston … but in an emergency its possible )
They are better than nothing – but only barely
They are easier to use, and cheaper to feed, than a long bow/cross bow
They are more accurate then both a long bow/cross bow, and slingshot, in untrained hands.
Can be used to intimidate someone, who doesn’t know any better.
Can take quite large game with good shot placement, and in a pinch.
Good practice for the real thing
But they have a down side:
Firarms should really only be for self defense, and traps, used for hunting.
Hunting with anything, is less effective than trapping … so rather trap
They are quite heavy and bulky – this means they don’t fit well in a bug out scenario.
In a land where firearms are restricted:
for self defense – get a cross-bow or a slingshot-bow, they are more lethal for one attacker.
for hunting rather use traps.