My brother pointed this out to me last night as we talked about guns. He just returned from a multi state car trip where he was (as a side benefit) stopping at random gunstores in the middle of nowhere and picking up ammo. He pointed out that if he had a lot of 'non-standard' calibers, he could still feed his guns.
9mm Para, 22LR, .357Mag, 223/5.56, 308, 45ACP, .30-06 were all gone.
Things like 10mm, 9mmMak, 7.62x25, .243Win, .454Casull, 7mm-08, etc..
were instock and plentiful.
I think it might be a good time to look at the used market, and buy a
gun in a non-standard caliber that someone is panic selling to buy an
AR-15 at 3x it's regular cost