The Trijicon TA31RCO-M855 (MPN TA31D100582) is the Rifle Combat Optic variant built for the M16A4/M4 family, combining tritium and fiber-optic illumination so the horseshoe-and-dot reticle never needs a battery.

Key Specifications

• Magnification: 4x
• Objective Size: 32mm
• Illumination Source: Fiber optics and tritium
• Reticle Pattern: Horseshoe w/Dot, Target Reference System
• Calibration: .223, 14.5 or 20 in. barrel
• Length/Weight: 6.0 in. / 14.2 oz.
• Eye Relief: 1.5 in.
• Mount Included: LaRue Tactical LT799
• Housing Material: Forged aluminum

Frequently Asked Questions

What mount comes with the RCO?

It ships with a LaRue Tactical LT799 mount along with external 1/10 mil adjusters, a scopecoat, and a LENSPEN.

Does the RCO need a battery?

No, the dual illumination system uses fiber optics for daylight and tritium for darkness, so it never depends on a battery.

What barrel lengths is the M855 reticle calibrated for?

It’s calibrated for .223 out of either a 14.5 in. or 20 in. barrel, covering both the M4 and M16A4 platforms.

Buy the Trijicon ACOG 4×32 TA31 RCO Riflescope, Dual Illuminated Red, M855

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