I’ve been learning gun smithing for a few years now ...
You should be able to field strip everything you have and then some. Lots of info on the web, and gunsmithing videos and texts are available, too. Find out the weak points in your most utilitarian arms, and get some spare parts for the ones most likely to wear out or break. (Springs, firing pins). Many older service issue bolt action rifles will likely outlast the zombie apocalypse given a good cleaning and decent care.