Depending on location, experience and such, hogs can be easy or hard to get.

One thing that normally works extremely well is baiting.
This may not seem advantageous in a SHTF situation, but talking to your local produce manager,
you can often score rotten vegetables and fruit to use as bait for nothing.

Secondly, waiting over the bait at night.
Makes the hogs hard to see, but they can’t see you also.
Using a red lens light, you can light them up without disturbing them.

I’ve seen some spectacular successes and failures with various guns.
And a lot depends on where the hogs have been, if they’ve been wallowing in the mud and it’s
dried and caked in place, it’s almost like a layer of armor.

Bullets that normally expand and drive deep, sometimes blow up within inches instead of penetrating where needed because of that mud.

Personally, after having shot a number of hogs with a variety of guns, I have found that I really like the .30 calibers such as .308 and .30-30. Moderate recoil, easy to handle, plenty accurate, and depending on what gun you use, you can ofter get a second hog with a fast second shot.

Last time I was out, we were after a number of hogs that were destroying fields near a reservoir.
Between three of us, we got 11 hogs in two ‘ambushes’, thanks to some fast shooting.
A number of freezers were filled that day.
It didn’t make a large dent in the population that day, the farmer who we were helping reported several herds of 30-50 roaming the area, which corresponded with ‘wildlife’ officers reports. They were breeding faster than anyone could kill them.

We weren’t picky about size, but shot everyone we could get sights on. The small ones were processed for food, the large gamy animals became dog food.