How to Use a Trijicon ACOG Scope

How to Use a Trijicon ACOG Scope?

Trijicon is a famous brand when it comes to ammunition accessories has developed a tactical scope known as Advanced Combat Optical Gunsight or ACOG. The scope is for tactical firearms in different kinds of lighting conditions.

The reticles of the ACOG scopes illuminate without batteries. The scope combines fiber optics that react to the background light, which provides optimum reticle illumination no matter how dark the area is.

Not all know how to use a Trijicon Acog Scope. So, we have written this guide to help you out. But, before we proceed with the process, you need to prepare the things you need.

The Primary Function of ACOG Scope

The ACOG scope was designed for American M16. But now, this Trijicon ACOG scope is a popular sighting system used for different purposes across several platforms. It has been used on and off the battlefield.

Trijicon ACOG scope has dominated the market because of its durability and versatility. Hunters, collectors, and hobby shooters love its design and features. For avid shooters, they do not care if the Trijicon ACOG scope is worth thousands of dollars as it is worth buying for.

What You Need

  • Firearm with flat-top scope mounting rail
  • ACOG Scope
  • ¼ inch flat-head screwdriver
  • Lenspen

Steps on How to Use a Trijicon ACOG Scope

Using the Trijicon ACOG scope is not as hard as you think it is. Just follow the steps below so you will not have problems using it.

Step #1 Check Your ACOG Scope

The first step is to inspect your ACOG by bringing it in the darkroom and give your eyes some time to adjust in the dark for around one to two minutes. The reticle is hard to see if your eyesight is not adjusted in the dark. Peek into the scope. If the ACOG is working well, it will be easy for you to see the illuminated reticle.

Step #2 Install the ACOG Scope

The next step is installing the ACOG scope. Loosen the knob found at the base of the clamp assembly. Position the scope on the flat-top rail, aligned the studs within the rail grooves. Tighten the knobs and use a flat-head screwdriver to make sure it won’t get loose. You can use a ¼ inch head screwdriver.

Step #3 Zeroing the ACOG

Make the needed adjustment to zero the ACOG. Next, determine the firearm’s point of impact in the center of the reticle using a boresighter or live ammunition at a target range. Make the needed adjustment on the scope axis until you hit the point of impact is near or almost the center of the reticle.

Zeroing your ACOG will help you hit your target accurately. The Trijicon Advanced Combat Optical Gunsight is an optical sighting system that enables you to hit your target using an illuminated target reticule.

The reticules are available in various shapes like a triangle, circle, chevron, or crosshair. The adjustment is done until you center the point of aim. Once zeroed, you can hit the target within a certain degree of accuracy, referred to as MOA or the minute of angle. The MOA and type of ACOG used are different for each firearm. Generally, the ACOG is zeroed at 100 meters, but you can also zero it at 100 yards.

The measurement of the ACOG increments is at a ¼ inch per click within 100 meters. So, you require four clicks to move the reticle center at a range of 100 meters. The reticle adjusters are found on the right side on top of the scope.

Step #4 Clean the ACOG

The final step is the cleaning of your ACOG. Your ACOG usually includes the cleaning device known as the lens pen. Use the brush side to remove any dirt or materials that could block the lens. After removing the particles of dirt, finish the cleaning process with the pen’s felt cleaner.

Frequently Asked Questions (FAQ)

New users of the Trijicon ACOG scope usually have some questions in mind. Some of their questions are as follows:

Which ACOG do the Marines use?

The United States Marine Corps use Trijicon ACOG TA31RCO 4 X 32 Scope in their operations. This rifle has 4x magnification with a 32mm objective lens, it has unique ballistic compensating reticles that are tritium and fiber optic illuminated for the M16A4 rifle and M4 Carbine.

It enables the aiming point to get illuminated even without the use of batteries. The sight is intended for Marine Corps AN/PVQ-31 Rifle Combat Optics. Additionally, every Carbine and rifle in the Marine Corps is equipped with an ACOG scope.

What Trijicon ACOG does the military use?

The US Army prefers Trijicon ACOG as their field carry optic. It features long eye relief, battery-free illumination, and a BDC reticle. The ACOG is designed for the M4 weapon system. Your target is illuminated even without batteries because of its dual illumination technology – a combination of self-luminous tritium and fiber optics.

The Trijicon ACOG meets the US military specifications. Its distinct reticle pattern offers easy acquisition of the target at close combat ranges as it provides enhanced target identification and can hit 800 meters with its Bullet Drop Compensator. In addition, the scope does not require any windage and elevation adjustments tool because it features TA31RCO-M150CP external elevation and windage adjusters. It also makes it waterproof up to 11m without caps.


If your ACOG requires some repair, make sure it is being handled by an expert or the manufacturer itself. It contains radioactive material, which is a bit dangerous when mishandled. For cases like broken or leaking scope, place the accessory into a sealed plastic bag. Ensure to wash your hands thoroughly with water and soap and call the manufacturer for instructions on how you will handle it. Never attempt to fix it on your own if you do not know about it, as it can cause bigger problems.


If you are having difficulties while zeroing your ACOG, do not force the reticle adjusters. It could affect the internal prism assembly. If this happens, call the manufacturer to assist you and give you instructions on what to do.

For defective ACOG, call the manufacturer for assistance as to how you can get a replacement.

Final Thoughts

The ACOG scope is beneficial for short-range and is best used on assault rifles. The primary advantage of the Trijicon ACOG scope, if appropriately used, is that you can see your opponents before they see you and eliminate them right away. Because of the accuracy and precision of ACOG scope, the US Military and Marines choose to use it for their ammunition. If you want to know more about the scope, comment below your questions. 

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