But Army officials here say the new M855A1 Enhanced Performance Round -- with its steel core instead of a toxic lead slug -- is far more effective than the current round, doubling the effective range and for the first time giving M4-wielding Joes the ability to penetrate barriers once reserved for higher-caliber rounds.
Army engineers at Picatinny Arsenal, N.J. designed a 5.56mm rifle cartridge that incorporates a jacketed copper slug pushing a sharpened steel "penetrator." Testers showed during a May 4 demonstration here that the round can punch through quarter-inch steel armor out to 300 yards with ease.