Trijicon ACOG 4×32 Dual-Illuminated M855

The Trijicon ACOG 4x32 is a fixed-magnification optical sight that uses dual illumination—fiber optics for daylight and tritium for low-light—to provide a consistently visible red aiming point without batteries. It is described as calibrated for .223/M855 ballistics on 14.5 or 20 inch barrels and is intended for AR/M16 platform use where rapid target acquisition and sustained situational awareness are required.

The provided product text references both TA31USN-M855 and TA31RCO-M855 designations and lists a package for the TA31RCO-M855 that includes a LaRue Tactical LT799 mount and several accessories; see notes for data conflicts and verification needs.

Key Specifications

• The magnification is 4x.
• The objective lens measures 32 mm.
• The illumination source is fiber optics and tritium, providing day and low-light visibility without batteries.
• The reticle pattern is a horseshoe with center dot and Target Reference System in red.
• The sight includes a bullet drop compensator and is described as providing engagement data out to 1000 meters.
• The calibration is .223 for 14.5 or 20 in. barrels.
• The eye relief is 1.5 inches.
• The field of view at 100 yards is 36.8 ft (approximately 7 degrees).
• The unit is described as waterproof to 11 m without caps.
• The housing material is forged aluminum.

Built around a proven fixed-power optical system and a rugged forged-aluminum housing, this ACOG configuration is presented for users who need a low-maintenance, daylight-to-dark aiming solution for AR/M16-style platforms. The dual-illumination reticle and built-in ballistic compensation make it suitable for disciplined shooters who prioritize reliability and straightforward aiming references in mixed light conditions.