The thing about survival that has to be taken into consideration is the firearm has to work in the very worst of conditions. What if you ......... It is your life. If you think an autoloading firearm will work for you, then bet your life on it. I would, however, take one out on a test run for a month in the wilderness and see how it holds up without the support from your bench at home. I prefer a single shot or revolver, but I want no say in what you choose. The idea about the contender with say a 45/410 barrel and a twenty-two barrel would fit what I am talking about. A single six and single shot rifle. The 357 revolver and lever would work but I would choose the long gun in a single shot like CVA, handy rifle, or Henry. One factor that was mentioned was weight. The handier, lighter without sacrificing reliability, a firearm can be, will work better in this situation. The gun must be able to work when wet, muddy, dusty, frozen, or banged around. To get from point a to b, you may have to swim, wade though swamp slim, or across desert like terrain. You may slide down a mountain side or any number of conditions. This is not even taking into account if you have to evade being found.
During this time, the first three to four days you will cling to your urban ways and values. After that you will eat and drink things you never thought you could. Many will give up and die the first time they get heat exhaustion. Those who survive will give up the idea of rest and comfort and chose to go on even if they only die in the end. Once you accept death and decide to go as far as you can anyway, you have a chance. You can live a long time on nearly no food at all or very little. It is water that is the key. You need it on a regular basis and you need to know how to find it and when you do find it , you need to drink it. If you drink water with unhealthy things in it you will become weaker. That is better anticipated and prepared for ahead of time with what you are carrying. That was the weak point in my survival experience. Drink bad water, and you have bad experience. Make room for whatever it take to have good water even at the expense of firearm or ammunition.