So two firearm cartridges I had a long interest in since I heard about them during the late 80's are the 10mm and .41 AE. The 10mm was adopted by the FBI after the 1986 Miami after they reach the conclusion that they needed a more powerful Pistol, which saved the cartridge from extinction and later lead to the .40 S&W. The .41 AE was intended as an upgrade to 9mm Luger weapons by using a rebated rim the same size as the 9mm. Which only required changing a few parts. It had around the same performance level of the .40 S&W.
https://en.wikipedia.org/wiki/1986_FBI_Miami_shootout
https://en.wikipedia.org/wiki/10mm_Auto
https://en.wikipedia.org/wiki/.41_Action_Express
https://en.wikipedia.org/wiki/.40_S&W
As far as I know, the .41 AE is no longer manufactured but the brass is still produced for reloaders.
https://en.wikipedia.org/wiki/1986_FBI_Miami_shootout
https://en.wikipedia.org/wiki/10mm_Auto
https://en.wikipedia.org/wiki/.41_Action_Express
https://en.wikipedia.org/wiki/.40_S&W
As far as I know, the .41 AE is no longer manufactured but the brass is still produced for reloaders.