The popularity of .22LR cartridge ammo among recreational shooters caused manufacturers to discontinue .32 rimfire following WW2.
Today, there are countless antique rimfire firearms in good shooting condition, and owners have to be creative in order to keep shooting their old rimfire rifles and revolvers.
There have been some creative cartridge conversions discovered and shared that have solved the problem of obsolete rimfire ammo shortages.
The most convenient, in my opinion are the custom machined hand reloadable brass cases, designed to use 6mm Flobert crimped blanks as primers, and 0.310" or 0.315" roundball plus black powder/pyrodex.
There are two companies in Belgium & France that offer reloading kits and supplies form many of the various obsolete rimfire & center fire cartridges.
A few American shooting supply companies also sell similar 6mm blank primed brass cases.
I lucked out and have bought 11 x .32rf short and 14 x .32rf Long cases from a terrific fellow in Alberta, Canada.
They aren't cheap, the last 10 x .32rf Long cases cost $102 including postage, and arrived 3 business days after I paid for them!
I have read that people report reloading these cases 30 times, and they are still in great shape.