M855

British SS109 5.56mm Ammunition: Cartridge, Caliber 5.56mm, Ball, L2A2 (United Kingdom) Under STANAG 4172 (standardization agreement)5.56x45mm NATO is the standard intermediate cartridge chambering for NATO forces.  SS109 NATO (known as M855 in the United States) is the 62 grain cartridge with a copper jacket, lead …