The TA31RCO Advanced Combat Optical Gunsight (ACOG) is purpose-built for the M4 and M4A1 weapon systems with a 14.5" barrel. It features dual-illumination technology, combining fiber optics and self-luminous tritium to provide a constantly illuminated reticle—without the need for batteries.
In low or no-light conditions, tritium ensures a visible aiming point, while the fiber optic system automatically adjusts brightness in daylight based on ambient light. This enables rapid target engagement with both eyes open, maximizing situational awareness.
Designed to meet the exacting standards of the United States Marine Corps, the reticle supports fast target acquisition at close range and precise engagement out to 800 meters using an integrated Bullet Drop Compensator (BDC).
The TA31RCO also features external windage and elevation adjusters for tool-free zeroing, and remains waterproof up to 11 meters—even without adjustment caps. Integrated mounting bosses near the eyepiece allow for easy attachment of a Trijicon RMR® (sold separately).
Key Features
- Designed for M4/M4A1 (14.5" barrel)
- Dual illumination (fiber optic + tritium)
- No batteries required
- Auto-adjusting reticle brightness
- Supports both-eyes-open shooting (BAC)
- BDC reticle for engagements up to 800m
- Fast target acquisition at close range
- Tool-free windage & elevation adjustments
- Waterproof up to 11 meters
- RMR® compatible (mounting bosses integrated)
Includes
- Thumbscrew Flattop Adapter (TA51)
- killFlash Anti-Reflection Device (TA91)
- Scopecoat (TA96)
- LENSPEN (TA56)
- Lanyard Assembly for Adjuster Caps (TA71E)
- Trijicon Logo Sticker (PR15)
- RCO Manual
- Warranty Card
| Specification | Details |
|---|---|
| Dimensions (L×W×H) | 5.98 x 2 x 2.3 in (151.89 x 50.8 x 58.42 mm) |
| Weight | 14.9 oz (422.41 g) |
| Magnification | 4x |
| Objective Size | 32 mm |
| Reticle Pattern | Chevron |
| Day Reticle Color | Red |
| Night Reticle Color | Red |
| Bullet Drop Compensation | Yes (.223, 14.5" barrel) |
| Bindon Aiming Concept™ | Yes |
| Illumination Source | Fiber Optics & Tritium |
| Power Source | Fiber Optics & Tritium |
| Eye Relief | 1.5 in (38.1 mm) |
| Exit Pupil | 0.32 in (8.13 mm) |
| Field of View (Degrees) | 7° |
| Field of View (Linear) | 36.8 ft @ 100 yds (12.27 m @ 100 m) |
| Mount | Flattop Thumbscrew Mount (TA51) |
| Housing Material | Forged Aluminum |
| Finish | Matte Black |
| Submersion Depth | -66 ft (-20 m) |
