The 6mm Ball International Match Cartridge was a Remington development in July 1960 and was based on the 250 Savage case necked to 6mm. At the same time the Advanced Marksmanship Unit (AMU) at Fort Benning developed a similar cartridge but with the neck moved slightly back. This specimen is the same as Fig. 790(B) in HWS 3 p. 535.