Most prevalent pistol cartridge in the world, and NATO standard. 'Nuff said.
9mm: The Cartridge of the Century? | An Official Journal Of The NRA (shootingillustrated.com)
"Originally made for German Navy Lugers in 1904, the 9mm is currently the most widely produced and sold pistol cartridge in the world.
"[Y]ou cannot deny the significance of what has happened. There is one hell of a lot of 9mm going through our fightin’ iron."
TDF INDEX: Cats, Guns, and National Security: THE DAILY FUDD index. https://catsgunsandnationalsecurity.blogspot.com/2021/03/the-daily-fudd-index.html