The Advanced Combat Optical Gunsight (ACOG) is a series of prismatic telescopic sights manufactured by

Trijicon Trijicon, Inc. ( ) is an American manufacturing company based in Wixom, Michigan that designs and distributes sighting devices for firearms including pistols, rifles and shotguns. Trijicon specializes in self-luminous optics and night sights, ...

. 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

reticle A reticle, or reticule also known as a graticule, is a pattern of fine lines or markings built into the eyepiece of an optical device such as a telescopic sight, spotting scope, theodolite, optical microscope or the screen of an oscilloscope, ...

s are illuminated at night by an internal

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus o ...

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 An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means t ...

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 Dry or dryness most often refers to: * Lack of rainfall, which may refer to **Arid regions **Drought * Dry or dry area, relating to legal prohibition of selling, serving, or imbibing alcoholic beverages * Dry humor, deadpan * Dryness (medical) * ...

. 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 The United States Special Operations Command (USSOCOM or SOCOM) is the unified combatant command charged with overseeing the various special operations component commands of the Army, Marine Corps, Navy, and Air Force of the United States Arm ...

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

s, 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

. The

tritium illumination Tritium radioluminescence is the use of gaseous tritium, a radioactive isotope of hydrogen, to create visible light. Tritium emits electrons through beta decay and, when they interact with a phosphor material, light is emitted through the proces ...

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 An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...

. 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 ...

s. Some ACOG models incorporate rudimentary

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

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 sig ...

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 Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environme ...

up to . Although the ACOG is designed for the

of the

M16A4 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, 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 The Heckler & Koch HK416 is a gas-operated assault rifle chambered for the 5.56×45mm NATO cartridge. It is designed and manufactured by the German company Heckler & Koch. Although the design is based on the AR-15 class of firearm (specifical ...

, Bushmaster ACR, Enfield L85A2, and

FN SCAR The FN SCAR (Special Operations Forces Combat Assault Rifle) is a family of gas-operated short-stroke gas piston automatic rifles developed by Belgian manufacturer FN Herstal (FN) in 2004. It is constructed with modularity for the United State ...

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 An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks through the device. The ...

as a

collimator sight A collimator sight is a type of optical sight that allows the user looking into it to see an illuminated aiming point aligned with the device the sight is attached to, regardless of eye position (with little parallax). They are also referred to as ...

. 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 The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Humans a ...

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

has been the subject of some criticism for inscribing a reference to a

Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts of a ...

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 The Heckler & Koch MG4 (also known as the HK123) is a belt-fed 5.56 mm light machine gun designed and developed by German firearm manufacturer Heckler & Koch. It was developed in the late 1990s and first seen publicly in September 2001. It has be ...

. *:

British Army The British Army is the principal land warfare force of the United Kingdom, a part of the British Armed Forces along with the Royal Navy and the Royal Air Force. , the British Army comprises 79,380 regular full-time personnel, 4,090 Gurk ...

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 The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is the ...

(see below), various law enforcement agencies. **The

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

Air Force An air force – in the broadest sense – is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an a ...

and

Marine Corps Marines, or naval infantry, are typically a military force trained to operate in littoral zones in support of naval operations. Historically, tasks undertaken by marines have included helping maintain discipline and order aboard the ship (refle ...

field the Trijicon TA31RCO ACOG, a 4× magnification model with a 32mm

objective lens In optical engineering, the objective is the optical element that gathers light from the object being observed and Focus (optics), focuses the ray (optics), light rays to produce a real image. Objectives can be a single Lens (optics), lens or mirr ...

(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 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 ...

used by

Special Operations Special operations (S.O.) are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment". Special operations may include ...

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 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 co ...

-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 The Heckler & Koch G36 (Gewehr 36) is a 5.56×45mm assault rifle designed in the early 1990s by German weapons manufacturer Heckler & Koch as a replacement for the heavier 7.62×51mm G3 battle rifle. It was accepted into service with the ''Bu ...

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 Lewis Machine and Tool Company (LMT) is an American armaments company founded by Karl Lewis, in 1980. LMT manufactures weapon systems including the M4 carbine, and the M203 grenade launcher. LMT products are used by the military forces of the Uni ...

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