Centerfire cartridges didn’t inspire quite as big a feeding frenzy, maybe because people don’t shoot them as much and because they can be readily reloaded. Some popular loads were hard to find but even if your favorite .243 or .308 hunting load was out of stock, there was likely something you could use. As a reloader I tend to think in terms of components rather than loaded ammunition.

For cartridge cases the situation right now is the best I can recall. Most popular cartridges are readily available and even obscure ones can usually be special ordered. We have more brand choices than ever — Winchester, Remington, Federal, PMC, Alpha, Hornady, Lapua, Norma, Nosler, Starline.
For big-game cartridges, which might be used to take three or four game animals a year, even 50 cartridge cases will keep you in business a long time. Personally, I like to have 200 to 250 cases on hand for a big game rifle — enough for load development and annual sighting-in checks. For cartridges I shoot a lot, such as .223 Rem. I think in terms of thousands.