Trijicon TA31RCO-M855 ACOG | 4×32 Red RCO

The Trijicon TA31RCO-M855 ACOG is a battery-free 4×32 combat optics sight that combines fiber-optic and tritium illumination for a consistently visible aiming point in a wide range of lighting conditions. Designed to the United States Marine Corps specifications, the reticle features a horseshoe with center dot and a Bullet Drop Compensator (BDC) calibrated for .223 with either a 14.5″ or 20″ barrel. The unit offers quick target acquisition at close ranges while providing reference holds for extended distances.

Applications include duty/field optics for service rifles and precision target reference at the range. Its rugged forged-aluminum housing and external adjusters are suited to professional and serious recreational use.

Product Specifications

• The magnification is 4x for consistent mid-range sighting.
• The objective size is 32 mm for a compact profile.
• The optic includes a Bullet Drop Compensator (Yes) for elevation reference out to longer distances.
• The overall length is 6.0 inches.
• The weight is 14.2 oz.
• The illumination source is Fiber Optics & Tritium, providing day and night visibility without batteries.
• The reticle pattern is a Horseshoe w/Dot w/ Target Reference System.
• The day reticle color is Red.
• The night reticle color is Red from the self-luminous tritium element.
• The calibration is .223 (14.5 or 20 in. barrel) for the included BDC markings.
• The Bindon Aiming Concept compatibility is Yes.
• The eye relief is 1.5 inches for consistent cheek welds on service rifles.
• The exit pupil is 8 mm to aid sight picture clarity.
• The field of view is 7 degrees (approx. 36.8 ft at 100 yards).
• The adjustment at 100 yards is 2 clicks/in and the unit features external adjusters without tools.
• The mount included is TA51 thumbscrew mount.
• The housing material is Forged Aluminum.
• The UPC is 719307312135.

Durably built and purpose-designed, the TA31RCO-M855 offers a straightforward aiming solution for users who require a battery-free illuminated reticle and a factory-calibrated BDC. Its compact footprint, proven reticle layout, and rugged construction make it suitable for professional service roles and disciplined range work where fast acquisition and consistent reference holds matter.