My favorite caliber, .45 Colt, none! Because I don't own a revolver in that caliber at this time, something I'll have to remedy soon. Here we are also limited as to the number of cartridges we can store, depending on caliber. A lot of calibers are limited to 1K rounds per gun. Some calibers, like .22lr, even .300 Blackout, or .44 Mag aren't limited, while .357 is limited, go figure... Nobody ever said gun laws were intelligent, anywhere. You can't own a cartridge you don't own a gun for, but there are exceptions to that. Gun laws aren't simple either, anywhere, except when totally prohibited.
So, usually I keep around 400 rounds per gun, sometimes less, more .22s.
What I started doing, is when my cases start to split after many reloads, I condemn the batch to a last reload, to be stored. So, my numbers will probably grow to the legal limit.
Gil.