6.5 x 55

6.5 x 55, also known as 6.5 x 55 Krag, 6.5 x 55 Mauser and 6.5 x 55 Scan among others, was developed by a Norwegian-Swedish committee in 1891 for use in the new rifles then under consideration in the two nations. Allthought agreement was made on the standard cartridge, Norway adopted the Krag-Jørgensen, while Sweden adopted a Mauser type rifle.

Due to different interpretations of the standard, i.e. the standards of manufacturing using maximum chamber in the Krag vs. minimum chamber in the Swedish Mauser, a small percentage of the ammuninition produced in Norway required a certain push on the bolthandle to chamber in the Swedish gun. After the rumor first surfaced in 1900, it was examined by the Swedish military. They declared the difference to be insignificant, and that both the Swedish and Norwegian ammunition was within the specified parameters laid down. Despite this finding, the Swedish weapon-historian Josef Alm repeated the rumour in a book in the 1930s, leading many to believe that there was a significant difference between the two types of ammunition.

Early Norwegian ammunition was loaded with a 10.1 grams (156 grains) long round nosed bullet (B-projectile) had a muzzle velocity of around 700 m/s (2300 ft/s), while later rounds had a 9 grams (139 grains) spitzer bullet (D-projectile) and offered a muzzle velocity up to 870 m/s (2854 fps).