I suppose it depends on the situation. Just for self defense an ak 47 pistol might be nice. For a longer period of time where food might be short maybe a shotgun would be more useful.
I'm torn between my Marlin model 60 or an AR15. Depends on the circumstance. If I'm out for the long haul, the 22 wins. I'f its only for a few days, AR15.
12 ga pump shotgun. Will handle 2 legged, and 4 legged animals all day/night. Ammo is common, can be cut down to fit your needs.(who is concerned about law in SHTF) can also take apart and use a duffle to transport. Will last a while with minimum maintenance, and many models are similar in reference to parts replacement.
Glock 19 with a threaded barrel. Concealable when I go to town. I know how to fight with the thing. I am also a pretty good shot, marksmanship wise, so I could hunt some types of game with it. (I also have 9mm shotshells for it). It runs every type of ammo I have ever fed it from steel cased Wolf, to 147g JHP subsonic to +P ammo. Put a can on it and it has even more capability for offence (yes you heard me right) as well as poaching. I can carry a bunch of ammo for it. I could probably scrounge ammo for it. 9mm is easy to reload using a hand press. Its the AK of pistols. Rugged reliability.
I tend to like the 22lr. Specifically the ruger 10/22 takedown and ruger mark 3 hunter. The 10/22 takedown breaks into 2 peices and could easily be stored in a back pack (ironically it does come with a storage pack new). The mark 3 hunter is a 22lr handgun which i have seen video of people plinking targets at 200 yds. Both are made of stainless, both reasonably priced, both use among the cheapest ammo available (which makes stock piling more economical). Downside is that both of these are very hard to find right now, hoping to get lucky at the 1500 this weekend.
Mine would be my henry survival rifle.. I have 2-8rd mags and 2-15rd mags.. Folds up very small and eats any ammo I put through it. It is also very accurate, I can shoot a 50 cent piece at 30yds which IMHO is pretty decent. And ammo is light and WAS plentiful before the foil hatters bought it all lol
I would have to grab the 12 gauge. Ammo would probably one of the easiest to find. You have shot shells for birds and small game and slugs for long range hunting for bigger game. And of course buck shot for close range defense. You got it all in one gun. Thats just me
Tough choice. AR or 12ga pump shotgun. Versatility and ammo wise, probably the 12 ga. I would agree with 500 mag above. But, if I could have my ultimate choice I'd grab 2 weapons - a 9mm pistol and the 12 ga.