Trijicon TA31 ACOG Review: The Never-Fail Combat Optic

By Eric Perez

Combat veterans know all about the TA31 ACOG (Advanced Combat Optical Gunsight) prismatic scope from Trijicon. It’s been a mainstay of the troops since 1987 when it was first introduced, mostly because it “just worked” with minimal fuss while taking a lot of abuse. Quickly asserting itself as quite the force multiplier, the ACOG has changed since then, keeping up with the times and technology in the industry.

Specs and Stuff

The TA31 is packed full of features stemming from the latest tech while still staying true to the original purpose — a clear, solid all-around scope. Let’s lay out some of the specs first:

Eye Relief	1.5″
Exit Pupil	.32″
Field of View at 100 yards	36.8 feet
Length	5.8″
Reticle	BAC Horsehoe red dot
Waterproof	To 11 meters
Magnification	4x
Objective Diameter	32mm
Illumination	Fiber optic cable and tritium

At first glance, it seems like a regular compact 4X scope. To really understand why the TA31 is so good, you need to dive a little deeper.

Features of the TA31 ACOG

According to Trijicon, the TA31 is designed to “provide enhanced target identification and hit probability for the M-16 and AR-15 rifle out to 800 meters.” That’s 874 yards — not exactly the shortest of distances.

The glass is bright and clear, and considering the ACOG is very compact, I was pleasantly surprised to see how bright it was. Also, it features an illuminated reticle, but one that does not require a battery and will always be there when you need it. While a tritium insert provides one source of illumination, a fiber optic cable adds power when you’re in direct sunlight. If you find yourself on a day where you need to cut some of the brightness, a tiny piece of duct or electrical tape can black out part of the fiber cable. The best part is that there are no extra parts or tools to mess with — nothing to fail or corrode. The ACOG’s biggest draw, even here, is that it just works.

It’s also durable — the kind of durable I was accustomed to from previous ACOG models. In Afghanistan, I saw one get run over by a vehicle yet still operate flawlessly. While I certainly don’t advise you to run over your equipment just to see if it’ll still work afterward, it’s good to know that the TA31 can take a beating and still deliver.

One of the more fascinating features of the TA31 is the Bindon Aiming Concept, and this is where the bright glass really shines. It allows you to aim and shoot with both eyes open. While that might not sound like a big deal, once you understand how it works it becomes a lot more interesting.

Essentially, while one eye is viewing the larger, total picture, the other eye is looking through the reticle, where the optic’s horseshoe red dot is. The overall effect means that you’re seeing the red dot superimposed, like a holograph, over the total picture your other eye is seeing. In other words, it’s like looking through binoculars instead of a monocle.

Shooting with the Trijicon TA31

Conditions up here at high altitude in western Montana don’t always cooperate with what I need to get done, and yet sometimes those less-than-optimal conditions show me how something will perform in the real world. We all like the calm, clear days for shooting; I found myself, however, shooting with the ACOG in a blizzard: heavy snow, 25 mile-an-hour winds, and horrible visibility. After 45 minutes of setting up, my hands were cold and shaky, and I wasn’t sure if I’d be able to really showcase the TA31 accuracy that I had seen in better weather.

The TA31, it turns out, is even better than advertised. I mounted it on a custom, pared-down AR platform weighing just under 6 lbs. before optics. The scope barely made a difference in the total weight, which is exactly what I hoped and expected to see.

At 50 yards I put 10 rounds squarely into a quarter-sized group on a 3” target. At 75 yards on a 2” target, I did almost as well. With 100 yards, visibility was rough but the TA31 still did its job, seeing me to solid center-mass shots even with shaky hands.

Putting It All Together

While each of the features is great individually, the combination is a thing of beauty. The TA31 is a worthy optic, no matter what kind of rifle you’re running. The bottom line? You need one. It’s that good.

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