Trijicon | ACOG Army Rifle Combat Optic | 223 Rem | 5.56 NATO | Black

Trijicon's ACOG Army Rifle Combat Optic (RCO) is the fixed 4x32 scope developed for the U.S. Army's M4/M16 rifles, and it's become one of the most combat‑proven optics on the market. It runs Trijicon's signature battery‑free dual illumination -⁠- tritium for a glowing reticle in the dark, fiber optics that pull in ambient light to keep it visible in daylight -⁠- so there's no battery to fail or replace. The bullet‑drop‑compensating reticle is calibrated for 5.56 NATO out to 800 meters, and external windage/elevation adjusters mean no tools are needed to zero it.