Well, before you think you're going to be able to live off the land with your trusty survival rifle or shotgun, consider that if you've never killed, dressed and cooked an animal, the first time to do that isn't when you're standing in 33 degree rain, shivering and wondering how you're going to start a fire to cook a squirell - IF one ever comes by.

I'd like to chime in with the basic fact that the definition of a "survival gun" is a weapon used at a distance to kill game for food purposes. This is not the same as a defensive weapon, or even an offensive weapon, which is intended to shoot people.

Yes, you can hunt with a defensive or offensive weapon, but these tend to be larger, heavier guns like a Remington 870 Shotgun or any of the AR-15 Military rifles.

The combination guns - a rifle and a shotgun in one unit - are pretty neat as a survival gun. The M6 Scout, sadly no longer made, is one of my favorites. Mine is in .410/.22LR and it's pretty darn good for a simple gun.

I've also got an AR-7, which is a Semi-Auto .22. I like it for the "cool" factor - it is easily taken apart and all the parts fit inside the stock.
A more polished and solid gun is the Savage 24F in 12Ga over .223, a really nice gun.

Handguns are prolematic for survival situations. Many people suggest a long-barel .22, typically a Ruger, however I've found that "the authorities" tend to have issues with handguns that they don't have with a long gun. This has implications for your emergency kit.

One last thought - ALL guns need maintenance. ALL guns. I'm obsessive about cleaning my guns and storing them dry and STILL I found a little bit of rust on one of my guns yesterday. I nearly had a stroke.