When talking about ammunition, we need to realize that there is no perfect answer. I live and hunt in southeast Texas, my longest shots are in the 125 yard range. 200 yards is a long shot for this area. The only place we get to see 200 yards, much less shoot that far is either on a pipeline or a highline.
In New Mexico, west Texas, Arizona, Colorado,,, 200 yards might be a short shot.
Talking about stockpiling firearms and ammunition for a long term SHTF survival situation is like talking about trucks. Do you need a truck to pull a boat down to the local boat launch, or do you need a tractor trailer rig to pull 60 tons?
Someone in the south with dense timber will probably do just fine with a 30-30 or 308. Someone making 200 and 300 yard shots may need a 25-06, 7mm magnum, 300 Winchester magnum, 30-06,,,. Someone in Alaska where grizzly is an everyday threat, maybe something like a 338 Winchester Magnum, 375 H&H or 12 gauge slug.
Lets use this article as a generalization, rather then an exact science.
To kick off the discussion, lets start with the two boxes I bought today:
1 box – 30-30 Winchester (Remington core-lokt 150 grain).
1 box – 12 gauge 2 3/4 inch Winchester 1 ounce slug.