I love the 308 and other milsurp calibers, but there's something to be said for having an oddball caliber or three in your arsenal as well... During the "Great Ammo Shortage", because everybody and their brother has 223's & 308's, those were the first bullets/supplies to get snarfed up. There was about a year or so you could barely find .224, .30, 9mm, or 45ACP bullets to save your life, unless you were willing to pay through the nose at places like GunBroker... yet, even during the worst of it, "mm" bullets were still pretty much everywhere to be had.
My lesson was to diversify, and stock up... no need to buy out everything in sight, but now that supply is back to normal, and we should be relatively safe for the next four years, I'll never get caught up short again.