I've always been a fan of break action and lever guns for hunting.
My favorite utility rifles are Savage Model 24C combo gun in .22LR over 20ga cyl bore for small game, varmints, etc, and Savage Model 24V (can you tell I'm a savage fan? lol) in .30-30 over 20ga full choke for big game and birds. That's what I'm stocking up ammo for. The rest of 'em, eh not so much. 3 calibers with 3 distinct uses.
If S really HTF, the Ballester-Molina will go on the belt, the 24C will stay broke down in the pack, and the 24V will be in hand with a Sierra 125 spitzer on top and a load of #2 on the bottom, and I'd be heading up the 'holler.
If I find myself needing people-shooting weapon other than the .45 (which I don't expect to need immediately in a SHTF situation; if something happens, folk around here tend to pull together in times of crisis for the most part instead of turning on each other, and I 'spect we'd all already be out on patrol once the displaced cityfolk started showing up), I'd get down to the farm and pick up the Mini-14, Rem 870, or the M1 Garand from the family mini-arsenal. But in a pinch, I 'spect the ol' .45 and some #2 buckshot would be right dandy.
If worst comes to worst after a while and bullets get too expensive (as if they're not already, lol), there's the .45 caliber flintlock, ball mold, old wheel weights, and homemade black power. Or a compound bow, though I've never been a fan of bowhunting. Never been able to make a clean kill with one. But ya gotta do what ya gotta do, I reckon.