They may be playing loose with the numbers - but I have requests in at several online sites for .308 ammo that say they will let me know when they have some.
Although I have seen on the local gun trader site that folks have ammo and guns for sale.
You are correct. Finding .308 is nearly impossible — coast to coast. And, those who have .308 are selling insane prices, as in, more than double the cost of standard prices.
So, I understand what the blogger is saying, and I suspect you are right that while making his point he was playing a little loose with the stats.
Whatever the case, I do hope supply comes back into congruity with demand soon. Nobody wants to go to the range and shoot ammo that they cannot resupply.
In MN and WI there are Mill’s Fleet Farm Stores that seem to have ammo. I bought 800 rounds of 9mm, 400 rounds of .223 and 200 rounds of 38’s a couple of weeks ago. One store had a limit of 5 boxes per trip, so I made two trips. I travel for business and now have a policy of stopping at every Mill’s store I pass by and acquire some peace of mind. The gun shops I stopped at were basically out of ammo so try the lessor known stores like Mill’s.