9 mm Largo

The 9mm Bergmann-Bayard (9x23mm Largo, 9mm Bayard Long), was developed in 1910 for the Bergmann-Bayard model 1910 semi-automatic pistol used by the Danish military. The model 1910 and its cartridge were adopted by the Spanish and later many Spanish-made pistols were chambered for the cartridge, which has become more commonly known by its Spanish nomenclature; 9mm Largo.

Power is slightly greater than a standard-pressure 9mm Luger, though 9mm Luger +P exceeds the performance of the longer, but lower pressure 9x23mm Largo. It should be noted that while dimensionally almost identical, the 9x23mm Largo is a very different cartridge form the modern, high-performance 9x23mm Winchester. Firing a 9x23mm Winchester round in a 9x23mm Largo pistol endangers the shooter, as 9mm Largo pistols cannot handle the pressure genreated by the 9x23mm Winchester.