An ACOG or Advanced Combat Optical Gunsight is a series of prismatic, telescopic sights manufactured by Trijicon. The ACOG was originally designed to be used on the M4/M16 series of rifles but has seen expanded use and product expansion to cover a variety of firearms.

What makes an ACOG different?

What makes an ACOG different than other weapon optics are its original, defining characteristics. It is worth noting that there has been significant product expansion and most of these options are customizable.

The original unique characteristics of an ACOG were:

• 4×32 magnification and field of view to work with the Bindon Aiming Concept (BAC). This was essential for its military application where utilizing a both eyes open sight picture is required.
• Battery free illumination. The use of tritium and a fiber optic light pipe allows the ACOG to have a bright reticle during the day and a fuller one at night without any adjustments by the operator. This technology enabled automatic lighting adjustments by the optic itself based on the surrounding ambient lighting.
• Bullet drop compensating reticle (BDC). A reticle which allows compensation for bullet drop at longer distances. In addition, the use of horizontal hash marks on the BDC reticle allows for quick range estimation at various rifle ranges.

Why does the military use ACOGs?

Well, this story is best told by Trijicon here. In simple terms, the ACOG was a revolutionary product that provided for enhanced marksmanship on all weapons platforms. The durability, usefulness, and reliability of the ACOG was and still is unmatched by Trijicon’s competitors.

Are there different types of ACOGs?

The initial TA01/TA31 ACOG is the product everyone thinks of when mentioning an ACOG, but Trijicon actually makes a variety of ACOGs. A very useful comparison chart can be found here. Today, there is essentially an ACOG for every desired level of magnification, field of view, reticle, reticle color, lighting source (battery or natural), and effective range.

Who sells ACOGs?

The gold standard of ACOGs is Trijicon. They make the optics that the U.S. military uses for its infantrymen, but they come with an unmatched reputation for quality and performance. In addition, they come with a price tag commensurate with that quality and performance. As such, a variety of competitors, including Sig, Nikon, and Burris make ACOG substitutes. A variety of smaller manufacturers make ACOG clones.