Charlie, It's all ammo made originally for the Korean Military. When the Koreans went with the M16and later their own rifle in 5.56, the carbine became a standard secondary weapon. This was so till the government had enough weapons for all troops and reserves. That is when the carbine was phased out and all the ammo is slowly being sold off. It's really excellent ammo and as good as USGI and it's made to US specs.