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 si ...

. The ACOG was originally designed to be used on the

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

and

M4 carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO assault rifle developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively used by the US mi ...

, 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 size ratio called optical magnification. When this number is less than one, it refers to a reduction in size, so ...

levels from 1.25× to 6×. ACOG

reticle A reticle or reticule, also known as a graticule or crosshair, 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 electronic v ...

s are illuminated at night by an internal

tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...

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 ...

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

fiberoptic An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...

light pipe or are

LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresp ...

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

History

The first ACOG model, known as the TA01, was released in 1987. An example was tested on the Stoner 93 in the early 1990s by the Royal Thai Armed Forces. 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 A ...

selected the 4×32 TA01 as the official scope for the

and purchased 12,000 units from Trijicon. Between 2004 and 2005, the TA31RCO-A4 & M4 (AN/PVQ-31A & 31B) 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 or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionar ...

, prompting Trijicon to produce 100,000 units for the US Marines 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 to 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, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...

light pipe. 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 chevrons. Some ACOG models incorporate rudimentary

ghost ring Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescope ...

iron sights Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescop ...

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 aiming point or some image (helping to aim the device, to which the sight is attached, on the target) sup ...

s mounted on top, such as the TA11SDO (SU-258/PVQ) and the TA648MGO (SU-260P). The ACOG ECOS line features both of these secondary sighting systems on the same scope. Other features include

Picatinny rail The 1913 rail (MIL-STD-1913 rail) is an American rail integration system designed by Richard Swan that provides a mounting platform for firearm accessories. It forms part of the NATO standard STANAG 2324 rail. It was originally used for mount ...

s like the TA648MGO, flip caps, and the ability to be

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

up to . Although the ACOG is designed for the Picatinny rail of the M16A4 and M4, it can be mounted on the carrying handles of previous models by using a special adapter.

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 Optical telescope, telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks thro ...

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 a ...

. 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 angle, angular extent of the observable world that is visual perception, 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 elec ...

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 references to

Bible The Bible is a collection of religious texts that are central to Christianity and Judaism, and esteemed in other Abrahamic religions such as Islam. The Bible is an anthology (a compilation of texts of a variety of forms) originally writt ...

verses (e.g. JN8:12, referring to John 8:12, "I am the

Light of the World "Light of the World" ( ''Phṓs tou kósmou'') is a phrase used by Jesus to describe himself and his disciples in the New Testament.''Names and Titles of the Lord Jesus Christ'' by Charles Spear 2003 page 226 The phrase is recorded in the Gosp ...

") alongside the model numbers on their ACOG sights. Starting in late 2009, Trijicon began shipping sights to the U.S. military without Bible verses.

Users

Finnish Defence Forces The Finnish Defence Forces (FDF) (; ) are the military of Finland. The Finnish Defence Forces consist of the Finnish Army, the Finnish Navy, and the Finnish Air Force. In wartime, the Finnish Border Guard becomes part of the Finnish Defence For ...

: **The TA11 is used by

Finnish Army The Finnish Army ( , ) is the army, land forces branch of the Finnish Defence Forces. The Finnish Army is divided into six branches: infantry (which includes armoured units), field artillery, anti-aircraft artillery, Combat engineering, engineer ...

Jaeger platoons for

designated marksman A designated marksman (DM), squad advanced marksman (AD) or squad designated marksman (SDM) is a military marksman role in an infantry squad. The term ''sniper'' was used in Soviet doctrine although the soldiers using the Dragunov SVD were the ...

roles on

RK 95 TP The RK 95 TP (from Finnish , 'Assault Rifle 95 folding stock'), officially 7.62 RK 95 TP and commercially known as the M95, is a 7.62×39mm Finnish assault rifle adopted in relatively small numbers by the Finnish Defence Forces in the 1990s. T ...

and modernized

RK 62 The RK 62 (from Finnish , 'assault rifle 62'), officially 7.62 RK 62 and commercially M62, is an assault rifle manufactured by Valmet and Sako. It is the standard issue infantry weapon of the Finnish Defence Forces. The RK 62 was designed in ...

rifles **The TA11 is used also by

Finnish Navy The Finnish Navy ( , ) is one of the branches of the Finnish Defence Forces. The navy employs 2,300 people and about 4,300 conscripts are trained each year. Finnish Navy vessels are given the ship prefix "FNS", short for "Finnish Navy ship", but ...

coastal Jaeger units as a standard optic on

rifles * *: Used by Indonesian Army for standard Infantry Optic on Pindad SS2 rifles. also used by different units and branches. * *: Used on MARS-L rifles. *: Used on

Heckler & Koch MG4 The Heckler & Koch MG4 (also marketed as the HK123 and was previously known as the MG43 prior to its adoption by the Bundeswehr) is a belt-fed 5.56×45mm NATO light machine gun designed and developed by German firearm manufacturer Heckler & Koch. ...

. *:

British Army The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve perso ...

and the

Royal Marines The Royal Marines provide the United Kingdom's amphibious warfare, amphibious special operations capable commando force, one of the :Fighting Arms of the Royal Navy, five fighting arms of the Royal Navy, a Company (military unit), company str ...

. *:

United States armed forces The United States Armed Forces are the Military, military forces of the United States. U.S. United States Code, federal law names six armed forces: the United States Army, Army, United States Marine Corps, Marine Corps, United States Navy, Na ...

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

United States Army The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...

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 army aviati ...

and

Marine Corps Marines (or naval infantry) are military personnel generally trained to operate on both land and sea, with a particular focus on amphibious warfare. Historically, the main tasks undertaken by marines have included raiding ashore (often in supp ...

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

objective lens In optical engineering, an objective is an optical element that gathers light from an object being observed and focuses the light rays from it to produce a real image of the object. Objectives can be a single lens or mirror, or combinations of ...

(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 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 Special operations or special ops 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 ma ...

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 or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionary ...

-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 an assault rifle An assault rifle is a select fire rifle that uses an intermediate cartridge, intermediate-rifle cartridge and a Magazine (firearms), detachable magazine.C. Taylor, ''The Fighting Ri ...

rifle attached with Trijicon ACOG 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 File:Pindad SS2-V4 A1 dengan picatinny rail.jpg, An SS2 equipped with ACOG

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