What is Caliber 9 mm Largo?

The 9 mm Largo is a semi-automatic pistol cartridge that originated in Spain and is also known as the 9 mm Bergmann-Bayard. It was developed in the early 20th century and is characterized by its slightly longer case compared to more common 9 mm cartridges, such as the 9 mm Parabellum. The 9 mm Largo was used in various military and police firearms, particularly in Spain, and has largely fallen out of widespread use in favor of more modern calibers. However, it is still encountered in some vintage firearms and among collectors.