Survival: continuing to exist in a mobile and upright state during times when the individual is beyond the normally accepted reach of human infrastructure.
I.E., living out in the environment too far to reach civilization, whether by choice or circumstance. Nothing TEOTWAWKI at all, you break down crossing North Dakota in a blizzard, run off the road in the Ouachita Forest, or have your pack animals eaten by a herd of grizzlies who break your elk rifle.
All you have left is Rifle X and you have to keep living for a few weeks/months until the CAP/Sheriff/local drug growers stumble across your living carcass.
Big Hint: GI survival rifles for pilots were .410/22 over unders.
What you can shoot in abundance is small game - birds, rodents, squirrels, rabbits, woodchuck, duck, muskrat, etc. Much larger actually is a waste - it spoils faster than you can eat it, attracts aggressive predators, and can be difficult to process by hand.
A .22 gets the job done in a survival state, you can carry lots of ammo and it's not heavy. Single shots don't have cycling issues or jam, and conserve ammo. A small shotgun is equal, and for a nonproficient or injured shooter, a more sure shot.
A .308 bullpup battle rifle? Not. Consider the source, and then treat it appropriately. Again, what professionals have devised and preferred for decades longer has been a .22 or small gauge shotgun - and a 4" knife, an ax, and a container that can hold water. One serious consideration is that the individual may have a broken arm or leg - and shooting would be greatly impaired. A light .22 would be a far better choice than a 10 pound magazine fed bullpup. It's a one way range out there, the environment is the biggest enemy.