The Trijicon ACOG RCO M4CP 4x32 Rifle Scope Chevron Dual-Illuminated Red Reticle (SKU TA31RCO-M4CP) is the USMC Rifle Combat Optic for the M4 and M4A1 carbine: a fixed 4x, 32 mm ACOG with a red chevron bullet drop compensating reticle cut for a 14.5 in barrel, lit by fibre optics in daylight and a tritium lamp after dark with no battery of any kind.
How It Compares
The RCO models are the issued configurations rather than the commercial ones. This is the Marine Corps optic for the M4 and M4A1, quoted for hit probability out to 875 yd (800 m); the RCO A4CP is the same optic calibrated for the 20 in barrel of the M16A4, and the RCO M150CP is the US Army M150 version. The commercial equivalent, without the service accessories, is the ACOG 4x32 Chevron .223 BAC. Browse all rifle scopes, the Trijicon ACOG rifle scopes range or the full Trijicon optics range.
Ideal For
- M4 and M4A1 carbines with a 14.5 in barrel, where the reticle holds are cut to that barrel
- Shooters who want the issued USMC specification rather than the commercial equivalent
- Duty use where the killFlash and the Scopecoat matter as much as the glass
Key Features
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Reticle: Red Chevron BDC, USMC Rifle Combat Optic for the M4 and M4A1 carbine; hit probability out to 875 yd (800 m)
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Illumination: Dual illuminated: fibre optics (day) + tritium (night); battery-free
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Calibre Calibration: .223 / 5.56, calibrated for a 14.5 in barrel
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Mount: Flattop Thumbscrew Mount TA51 (included)
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Warranty: Trijicon Limited Lifetime Warranty
Technical Specifications
| Magnification / Objective |
4x fixed |
| Objective |
32 mm |
| Reticle |
Red Chevron BDC, USMC Rifle Combat Optic for the M4 and M4A1 carbine; hit probability out to 875 yd (800 m) |
| Reticle Colour |
Red |
| Calibre Calibration |
.223 / 5.56, calibrated for a 14.5 in barrel |
| Illumination |
Dual illuminated: fibre optics (day) + tritium (night); battery-free |
| Eye Relief |
1.5 in (38 mm) |
| Exit Pupil |
0.32 in (8.1 mm) |
| Field of View |
36.8 ft at 100 yards (12.3 m at 100 m); 7° |
| Weight |
14.9 oz (422 g) with the TA51 mount |
| Housing |
Forged aluminium (7075-T6), matte black |
| Mount |
Flattop Thumbscrew Mount TA51 (included) |
| Water Resistance |
Submersion depth 66 ft (20 m); dry-nitrogen filled, fogproof |
| What's Included |
RCO, TA51 thumbscrew flattop adapter, TA91 killFlash anti-reflection device, TA96 Scopecoat, TA56 LensPen, TA71E lanyard assembly, PR15 logo sticker |
| SKU / MPN / UPC |
TA31RCO-M4CP / TA31RCO-M4CP / 719307302075 |
Warranty
Trijicon back this with their Limited Lifetime Warranty: the optical system and metal structure are covered against defects in materials and workmanship for the lifetime of the original owner. The tritium lamp carries its own multi-year term from date of manufacture.
UK Delivery & Support
Delivery is a flat £5 by Royal Mail Tracked 24, UK addresses only, with no free-delivery threshold. Allow 7–10 business days from order to doorstep — most of that window is sourcing, and the Tracked 24 leg is the last day of it. Duties and import fees are prepaid, so there is nothing to pay on arrival. Questions about reticles, mounts or fit? Email info@xtremetactical.co.uk, or message us on WhatsApp or by text on +44 7940 435857 — messages only, we don't answer voice calls.
Frequently Asked Questions
Does it need batteries?
No — the reticle is lit by fibre optics in daylight and tritium in the dark. There is nothing to switch on and nothing to run flat.
What calibre is the reticle calibrated for?
.223 Remington and 5.56 NATO, with the holds cut for a 14.5 in barrel. The 20 in barrel version is the RCO A4CP.
What is the difference between the M4CP and the A4CP?
Barrel length. The M4CP reticle is cut for the 14.5 in M4 and M4A1, the A4CP for the 20 in M16A4. The optics are otherwise the same.
Does it come with a mount?
Yes — the TA51 Flattop Thumbscrew Mount is included, along with the TA91 killFlash anti-reflection device and a TA96 Scopecoat.
Can I shoot with both eyes open?
Yes — the ACOG is designed around the Bindon Aiming Concept for both-eyes-open shooting at speed.
What warranty does it carry?
Trijicon's Limited Lifetime Warranty. The tritium lamp carries its own multi-year term from date of manufacture.
Is this a genuine Trijicon product?
Yes — factory-new, genuine Trijicon, covered by Trijicon's Limited Lifetime Warranty.
