Living in a free state I have the opportunity to own an AK47 type rifle. As a SHTF defenseive weapon it really excells due to several factors. It is leathel at the 75 to 150 yards engaugement range; most gun fights take place at close range. The 7.62x39 round is relativily inexpensive. Lucky Gunner has a bulk pack of 1000 rounds listed for $209 currently, thats 20.9 cents a round. https://www.luckygunner.com/rifle/7.62x39mm-ammo
We buy our ammunition prior to SHTF events. Let me say you won't be able to but it later! There is a bunch of 7.62x39 ammunition available. Chances are it would be the type of ammuniton you might "aquire" in certain ways post SHTF.
The Ak platform is rugged, especially with a chrome lined barrel. It can take mud, rain, dirt, snow, and any crap you could put it through. Fact is, it runs and runs and runs. It is my SHTF (civil unrest) go to battle rifle. Oh yes, it has a bayonet lug. Nothing more intimidating, than a sharp pointy thing at the end of a rifle!
More improtantly there are three other weapons that I have for SHTF self defense and food gathering. First, I have a 22 cal rifle for small game gathering using relatively quiet sub sonic ammunition. Second, there is my pistol (a Glock 40cal) for up close self defense. Finally a good ol 12 gauge pump shotgun like my Mossburg works well with slugs for people or game and birdshot for dove and quale.
Come to think of it, maybe the best go to SHTF weapon is the shotgun with interchangeable 18" and 24" barrels!