[Buffalobob]

A Rem 700 action is about as common of an action as can be obtained. Spare parts are everywhere. If it is trued then accuracy will be extreme.

The 308 cartridge is about the most common cartridge available and can be obtained almost anywhere. It is available in many configurations such as Federal Gold Medal Match. If you learn to reload then ammo availability becomes less of a problem

The problem with a mid to long range survival rifle is going to be the sighting system. Telescopic sights are going to be a problem over the long term and the really durable systems are really expensive. Competition iron sights are not really geared for hunting and I do not know anyone who makes a really good and durable long range hunting iron sight. Parts and repair are going to be major problems to solve.

Something to consider is what does survival mean to you. There is the Mad Max wandering through post apocalyptic mutants and then there is Mormon stockpile food and water in your basement waiting for the Moroni to blow his horn styles of survival.