Barrett M82A1: This Is the Most Powerful Sniper Rifle To Ever Fire A Shot The Barrett .50 BMG was a shoulder fired, semi-automatic rifle designed around the .50 BMG cartridge. Unique among firearms, Barrett rifle’s barrel recoiled backward after firing. Here's What You Need to Remember: Today the Barrett M82A1 is used by more than sixty countries, mostly NATO countries and U.S. allies in Asia and the Middle East. All the major military powers field their own 12.7mm/.50 caliber-class sniper rifles, with Russia’s OSV-96 rifle serving with the Russian Ground Forces and China’s Zijiang M99 serving with the People’s Liberation Army.