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Advanced Combat Optical Gunsight

A 101st Airborne soldier searches for targets with his Advanced Combat Optical Gunsight (ACOG)

Until quite recently most infantrymen didn’t have an optical sight on their rifle. There were exceptions, of course; British infantry were issued with the SUSAT in 1986, every Canadian soldier got an Elcan C79 when the C7 rifle replaced the C1A1 SLR and Germany’s version of the Heckler & Koch G36 has two optical sights – a 3x scope graduated out to 800m and an unmagnified reflex sight for close quarter battle. Most armies stuck with iron sights, though. That really started to change during the current operations in Afghanistan. The US Army finally started issuing optics on a wide scale, and one of the designs they chose stood out so much that other armies quickly adopted it too. That design is the Trijicon Advanced Combat Optical Gunsight, or ACOG, and it’s actually a family of related scopes. It’s now in service with many nations, including the USA, UK, Germany, Norway, Finland, Saudi Arabia, Israel, South Africa, Turkey and others. Thousands of civilian marksmen have bought them too, despite a price tag that’s often well over €1,000.

Advanced Combat Optical Gunsight with reflex sight

An ACOG with built in reflex sight, mounted on a British L85A2 assault rifle.

What makes the ACOG popular? Well, for a start it’s compact. Most models don’t have a zoom function and use a fixed 4x magnification, so the lens size can be kept down to 32mm. This combination of size and power gives an 8mm “exit pupil” – the optical path directed out the back. 7.5 to 8mm is as much as a human eye can handle, so a larger lens is pointless. 8mm gives the best combination of brightness and small size. Trijicon do make a few larger ACOGs, including a 6x version used by the British Army on its L129A1 Sharpshooter rifle; this has a 48mm lens, so again the exit pupil is 8mm. Keeping the size down like this makes for a lighter scope, and one that won’t snag on obstacles so much or get in the way of operating the rifle’s action.

The Advanced Combat Optical Gunsight is tough. The body is a one-piece aluminium forging and compared to most hunting scopes it’s immensely strong. It’s also sealed so well that it’s watertight to 100 metres, meaning it’s totally proof against rain or immersion in rivers. Reticules are illuminated by tritium gas capsules at night and, in some versions, fibre-optic collectors during the day, so the scope doesn’t need any batteries. With the increasing number of batteries troops have to carry for night vision equipment, radios, GPS and other gear, not needing one for the rifle sight is a big plus.


Advanced Combat Optical Gunsight on mp5

The tiny size of this 2×20 ACOG makes it suitable for mounting on weapons as small as an MP5.

Finally the Advanced Combat Optical Gunsight is flexible. Many versions have an integrated reflex sight for close quarter battle; others have an M1913 rail on top so an emergency sight can be fitted. Different reticules are available to suit different calibres of rifle or styles of shooting. Some versions can be used together with night vision equipment. So many options are available that whatever you need from a scope, there’s an ACOG that can do it.

Trijicon have had public relations upsets, like when it was discovered that they were stamping coded Bible references onto their products, but overall they’ve come up with a great product and done a very good job of marketing it to western armies. Expect to see the ACOG showing up more and more often over the next few years.