I also think the .22 is better for survival because of the weight issues of ammo. Although the 12 Gauge is versatile, that versatility comes with the cost of several different types of heavy ammo. The .22 can let you pack a lot of ammo for relatively small amount of weight.

Thus, your ammo will last longer and you will harvest more small game. I agree that taking a deer an not being able to use all of the food is a waste. The leftovers could also attract predators you would prefer to avoid.

That last situation is the best reason I can think of for a heavier weapon in a purely survival situation: defense against a predator. Here on the US east coast and in the Allegheny Mountains, large predators are much less of a risk then say on the West Coast or Alaska---our black bears are much less aggressive than brown bears, and despite persistent rumors of sightings (and one or two confirmed) there is not a resident or permanent population of big cats to worry about. So, for purely survival on the east coast, I would go with a good reliable .22 and lots of ammo.

My understanding of Jackie's original post was to ask about how to get started, recognizing a potential for possible later hunting/survival uses. IMO, a .22 (almost any .22 rifle) is a great way to start/learn at a very reasonable cost, provides a lot of fun shooting, and retains significant utility for later survival and small game hunting (check local laws). I think it is the best "starter" gun, and a .22 and a good supply of ammo should be included in all preps that include firearms.