Shotgun 12 g single....as virtually nothing can fail on these and these are not especially ammunition sensitive. And anyway many on the American frontier used either double or single shotguns and so it is a proven system under difficult conditions.
Rifle; a .223 AK (BKW) or a Galil Variant. Reliable operating system, and a commonly available round in a balanced system which can be used for hunting, SD and to irritate anti RKBA's people. Perhaps not all that suited for heavy game, but good enough to stay fed with if needed. And a mix of 5 rd and standard mags.
Pistol/Revolver; any good qaulity .357 revolver. Flexible in loadings, and can use .38 special (and in situations of very limited ammunition a revolver can in a pinch fire similar ammunition. Not that it is recommended but there have been places in the past and present where this is done under difficult conditions)