The Advanced Combat Optical Gunsight (ACOG) is a series of prismatic telescopic sights manufactured by Trijicon. The ACOG was originally designed to be used on the

M16 rifle The M16 rifle (officially designated Rifle, Caliber 5.56 mm, M16) is a family of military rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56×45mm automatic rifle with a 20-roun ...

and

M4 carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO, gas-operated, magazine-fed carbine developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively ...

, but Trijicon has also developed ACOG accessories for other firearms. Models provide fixed-power

magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in siz ...

levels from 1.25× to 6×. ACOG reticles are illuminated at night by an internal tritium

phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or vi ...

. Some versions have an additional daytime reticle illumination via a passive external fiberoptic

light pipe Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

or are

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

-illuminated using a dry battery. The first ACOG model, known as the TA01, was released in 1987. USMC-08814

History

The first ACOG model, known as the TA01, was released in 1987. In 1995, United States Special Operations Command selected the 4×32 TA01 as the official scope for the

and purchased 12,000 units from Trijicon. Between 2004 and 2005, the ACOG was selected as the official Rifle Combat Optic of the

United States Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combi ...

, prompting Trijicon to produce 100,000 units for the

US Marines The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combi ...

in the following 18 months.

Design

The ACOG is available in a variety of configurations from the manufacturer with different reticles, illumination, and other features. Most ACOGs do not use batteries for reticle illumination, being designed to use internal phosphor illumination provided by the radioactive decay of tritium. The tritium illumination has a usable life of 10–15 years. Some versions of the ACOG have an additional daytime reticle illumination via a passive external fiber optic

. Normally this allows the brightness of the reticle to match the field of view since it collects ambient light from around the sight, although this can lead to a mismatch in lighting - such as sunlight hitting the light pipe directly, or standing in a shadow - causing the reticle to be much brighter or darker than the target. Reticles have other features such as a bullet drop compensator and other different reticle shapes such as

chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * ''Eulithis testata'', a moth * Chevron (geology), a fold in rock lay ...

s. Some ACOG models incorporate rudimentary ghost ring

iron sights Iron sights are a system of physical alignment markers (usually made of metallic material) used as a sighting device to assist the accurate aiming of ranged weapons (such as a firearm, airgun, crossbow or even compound bow), or less commonly ...

as a backup for targets that are within . Most ACOG models, when mounted to a carry handle, have an open space through the mount to allow the use of the rifle's iron sights without removing the scope. Others include Docter or Trijicon

reflex sight A reflector sight or reflex sight is an optical sight that allows the user to look through a partially reflecting glass element and see an illuminated projection of an aiming point or some other image superimposed on the field of view. These sigh ...

s mounted on top. The ACOG ECOS line features both of these secondary sighting systems on the same scope. Other features include

Picatinny rail The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail, 1913 rail or STANAG 2324 rail (cancelled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was o ...

s, flip caps, and the ability to be waterproof up to . Although the ACOG is designed for the

of the M16A4 and M4, it can be mounted on the carrying handles of previous models by using a special adapter. Trijicon later produced ACOG mounts and adapters for weapons besides the M16, including the

Beretta AR70/90 The Beretta AR70/90 is a gas operated assault rifle chambered for the 5.56×45 mm NATO cartridge, and is the standard issue service rifle of the Italian Armed Forces. The weapon is also designed to be fitted with a rifle grenade, and has gr ...

series;

SIG SG 550 The SG 550 is an assault rifle manufactured by Swiss Arms AG (formerly a division of Schweizerische Industrie Gesellschaft, now known as SIG Holding AG) in Switzerland. "SG" is an abbreviation for ''Sturmgewehr'' ("assault rifle"). The rifle ...

, Heckler & Koch HK416,

Bushmaster ACR The Adaptive Combat Rifle (ACR) is a modular assault rifle designed by Magpul Industries of Austin, Texas, and known initially as the Masada. In late January 2008, Bushmaster Firearms International entered into a licensing agreement with Magpul ...

Enfield L85A2 The SA80 (Small Arms for the 1980s) is a British family of 5.56×45mm NATO service weapons used by the British Army. The L85 Rifle variant has been the standard issue service rifle of the British Armed Forces since 1987, replacing the L1A1 S ...

, and FN SCAR weapon systems; and the

Steyr AUG The Steyr AUG () is an Austrian bullpup assault rifle chambered for the 5.56×45mm NATO intermediate cartridge, designed in the 1960s by Steyr-Daimler-Puch, and now manufactured by Steyr Arms GmbH & Co KG. It was adopted by the Austrian Arm ...

Bindon aiming concept

Several ACOG models are designed to be used with the "''Bindon Aiming Concept''", an aiming technique developed by Trijicon founder and optical designer Glyn Bindon. The technique is essentially using the illuminated part of the reticle and its focusing rear eyepiece as a collimator sight. As in any other collimator sight, the user does not actually look through the sight but instead keeps the collimated (infinity) image of the illuminated part of the reticle in focus with the dominant eye while the other eye views the entire field of view to acquire the target. In this both-eyes-open technique the brain superimposes the aiming reticle on the target. An added part of the technique is to shift focus after acquisition to the dominant eye/telescopic image for more accurate shooting. This overcomes the problem of centering or acquiring fast traversing targets common with all telescopic sights. Only certain models of the ACOG are designed with bright enough daylight-lit fiber optic or battery-powered LED reticles that facilitate this technique.

Controversy

Trijicon has been the subject of some criticism for inscribing a reference to a Bible verse ( JN8:12, referring to John 8:12, "I am the Light of the World") alongside the model numbers on their ACOG sights. Starting in late 2009, Trijicon began shipping sights to the U.S. military without the Bible verse.

Users

* *: Used on MARS-L rifles. *: Used on Heckler & Koch MG4. *: British Army and the

Royal Marines The Corps of Royal Marines (RM), also known as the Royal Marines Commandos, are the UK's special operations capable commando force, amphibious light infantry and also one of the five fighting arms of the Royal Navy. The Corps of Royal Marine ...

. *: United States armed forces (see below), various law enforcement agencies. **The United States Army, Air Force and Marine Corps field the Trijicon TA31RCO ACOG, a 4× magnification model with a 32mm objective lens (4×32), with specially designed ballistic compensating reticles that are fiber optic & tritium illuminated, for the

and M16A4 rifle. This sight is designated the ''M150 Rifle Combat Optic'' in Army service and ''AN/PVQ-31 Rifle Combat Optic'' in the Marine Corps. After an October 2005 evaluation, the USMC fielded 115,000 ACOGs so that every rifle and every carbine in the Marine Corps inventory would be equipped with one. **The TA01NSN, a 4×32 ACOG with only tritium night illumination and backup

, is included in the Special Operations Peculiar MODification (SOPMOD) kit for the M4A1 carbine used by Special Operations personnel to configure their weapons to individual preferences and mission requirements. Other Trijicon models have also seen service after being purchased at the unit and individual level. ** The Marine Corps field the Trijicon 3.5x35 SU-258/PVQ Squad Day Optic on the M27 assault rifle.M27 First Impressions
- Thefirearmblog.com, 20 April 2013

Gallery

File:M4-Transparent.png, An

with a TA01NSN ACOG. File:US Marine M16A4 Rifle ACOG.jpg, USMC-spec M16A4 fitted with ACOG, vertical foregrip, and AN/PVQ-31. File:Saber Strike 2017 Norwegian STX Lane 170604-A-YI894-0138.jpg, Latvian soldiers using a Heckler & Koch G36 rifle attached with Trijicon ACOG. File:USMC-08814.jpg, USMC 4×32 rifle reticle File:24th MEU's Headquarters and Service Company conducts live-fire exercise 150310-M-WA276-018.jpg, TA648 6×48 Machine Gun Optic reticle File:L129A1 Sharpshooter rifle MOD 45162218.jpg, A L129A1 sharpshooter rifle with a TA648-308 6×48 ACOG fitted

References

External links

* {{Official website
Japanese article with cross-section drawing of ACOG internal optical lay out

US patent 4806007A Optical gun sight
Firearm sights United States Army equipment Equipment of the United States Air Force United States Marine Corps equipment British Army equipment Military equipment introduced in the 1980s