Hornady Frontier XM193 5.56 NATO 55gr FMJ Rifle Ammunition – 600 Round Case (4 x 150rd Ammo Cans) Stock up on dependable, high-velocity 5.56 NATO ammunition with the Hornady Frontier XM193 55 Grain Full Metal Jacket, packaged in a 600-round case containing four 150-round reusable ammo cans. Built for shooters who demand consistency and reliability, this bulk configuration is ideal for high-volume training, range days, and keeping your rifle fed with proven M193-style performance.