The .308-caliber Trijicon ACOG (Advanced Combat Optical Gunsight)

 by John N. Raguso

Trijicon ACOG

Trijicon’s TA11E-A is a sturdy and robust combat optic that will excel in the field, featuring machined 7075-grade anodized aluminum sections that are perfectly mated, a GE Lexan Polycarbonate fiber optic light-gathering tube, a sturdy machined aluminum TA51 flattop mount, plus protected windage and elevation turrets that enable you to zero it in just right, no matter what .308 WIN or 7.62 x 51 NATO ammo you prefer.

Trijicon’s self-luminous aiming systems have been battle-tested by those who protect and defend us around the globe, rightfully earning the reputation as having some of the most sophisticated and dependable optics on the planet. Whether you’re doing a night sweep through enemy territory, defending an established position against multiple moving targets, or something more mundane like sighting in a Pennsylvania whitetail or a Texas hog in the extremely challenging low-light conditions of dawn or dusk, you might want to consider equipping yourself with the same optics that are now standard issue with many government agencies and military outfits the world over: a Trijicon ACOG.

Having just purchased a new 7.62×51 NATO-caliber Rock River LAR-8 A4 flattop this past fall and in the process of experimenting with various iron sights and optic systems, I decided that field testing a new .308-caliber Trijicon ACOG (Advanced Combat Optical Gunsight) would be worth the effort. And I was right. Come join me as I take you through the step-by-step of how to set up your favorite .308 Win./7.62 NATO-caliber rifle with one of the neatest low-maintenance, dual-illumination, no-battery, multi-mission sights to hit the market—ever.

Paired with this 20-inch S/S barrel Rock River LAR-8 Predator, the Trijicon TA11E-A forms a potent combo that presents a quick and accurate aiming point at a variety of ranges, thanks to its handy bullet drop compensator (BDC).


Glyn A. J. Bindon, who founded Trijicon back in 1981, was born in 1937 in Pretoria, South Africa and immigrated to the United States in the mid-50s, where he received a degree in aeronautical engineering. Having worked at various defense contracting positions in the ’70s with Grumman Aerospace and NASA, and then with Ford Motor company, Bindon was contemplating going out on his own. While visiting his family in South Africa in early 1980, he met the developer of the Armson OEG gunsight, who was attempting to introduce the OEG sight to the American market. The concept whetted Bindon’s interest, and upon his return home, he began importing those sights to the USA. He named his company Armson, Inc., and the Armson sights were his only product from 1981 until 1985.

After some initial success, Bindon began developing his own ideas for self-illuminated sights. Once he obtained the first “exempt” license from the US Nuclear Regulatory Commission for the Armson OEG, Bindon developed a line of tritium-equipped iron sights for handguns. The “exempt” status also allowed the new tritium sights to be distributed separately from the firearms themselves, and one early success with the night sights was their adoption by the FBI for use on their new auto loading pistols.

ACOG package

The ACOG package includes the TA11E-A sight, a sturdy Pelican travel case, a Scopecoat to protect the ACOG from dings and scratches when mounted on your weapon, a functional lens pen to keep your optical glass clean, an operator’s manual, lens pen instructions, warranty card and Trijicon decal. The M134 Mini-Gun ammo belt is not included in the kit.

Bindon eventually renamed his company Trijicon, Inc., and those night sights became the basis for the family-owned and operated company that grew quickly through its constant experimentation with innovative optics that truly pushed the envelope in optic design.

Following his success with night sights, Bindon’s next product was a reflection of his true inventor’s spirit when the Advanced Combat Optical Gunsight (ACOG) was developed contrary to most existing optical theory. Throughout his life, Bindon developed things that according to conventional thinking “shouldn’t work.” The ACOG was one clear example.

The combination of the rugged design of the ACOG, along with the integration of an effective fiber optics system, set the ACOG apart from all other rifle scopes. Then, his discovery of the Bindon Aiming Concept (BAC) drove him to merge fiber optic illumination and magnified optics. The result was that the ACOG permitted the fastest aiming possible while still allowing a magnified view for distance discernment.

During the mid-1990s two of Bindon’s optics were adopted as part of the US Special Operations Command SOPMOD M4 Carbine Accessory Kit: the Day Optical Sight 4×32 ACOG (Model TA01NSN) and the RX01NSN Reflex sight.

More recently, several US Army combat units and the US Marine Corps have procured the dual illuminated BAC version of the ACOG (Model TA31F) for use in Afghanistan and Iraq, while numerous other Federal Agencies and foreign allies employ various aiming systems developed by Bindon. His products have contributed significantly to our military’s combat effectiveness over the past two decades.

Glyn Bindon, founder and Chairman of the Board of Trijicon, Inc., died in September 2003, when his small plane crashed near Palmer, Alaska. He will be missed, but his company, unique spirit and corporate policies carry on in his absence.

Here’s a close-up of the Trijicon ACOG’s windage and elevation knobs with their protective turret caps removed. Each click of the rotary adjustment knobs will change your projectile’s point of impact by ¼ inch at 100 yards.


I know things are changing all the time in the world of all things firearms, but as of the time of writing this piece (late December 2010), Trijicon offered a total of 11 different basic .308-caliber ACOGs (along with numerous variations within these sub-groups, such as different color reticles) and I needed to pick one of them to conduct this weapons accessory evaluation test. That list included the following:

v  TA01B (4×32), with red/black crosshairs reticle and BDC to 800M (MSRP $1,112)

v  TA11C (3.5×35), with donut reticle and BDC to 800 M (MSRP $1,377)

v  TA11E (3.5×35), with chevron reticle and BDC to 800M (MSRP $1,428)

v  TA11H (3.5×35), with horseshoe reticle and target reference system and BDC to 1,000M  (MSRP $1,428)

v  TA11J308-G (3.5×35), with crosshair reticle and BDC to 1,200M (MSRP $1,428)

v  TA33-9 (3×30), with amber chevron reticle and BDC to 600M (MSRP $1,173)

v  TA33R-9 (3×30), with red chevron reticle and BDC to 600M (MSRP $1,173)

v  TA55A (5.5×50), with chevron reticle and BDC to 1,200M (MSRP $1,887)

v  TA648-308 (6×48), with red chevron reticle and target reference system, top rail mount for reflex sight and BDC to 1,200M  (MSRP $2,500)

v  TA648-308G (6×48), with green chevron reticle and target reference system, top rail mount for reflex sight and BDC to 1,200M  (MSRP $2,500)

v  TA648RMR-308 (6×48), with red chevron reticle and target reference system, 8 MOA RMR sight and BDC to 1,200M (MSRP $3,163)

Since I didn’t need to equip an F/N 240 machine gun with an optic with a bullet drop compensator (BDC) out to 1,200 meters, I eliminated the TA648 series of optics. The TA55A was a bit too long and cumbersome for my applications, so that was an easy deselect candidate, as well. I’ve never been a big fan of the “crosshairs” reticle, so the TA01B fell off the short list, too. This steered me to the TA11 family of ACOGs, with the chevron-style of reticle being my personal fave versus the donut or horseshoe types.

Now, the only question was green, red or amber? The Trijicon folks made that choice easy for me, since they only had an amber flavor in stock and I didn’t want to wait another 10 to 12 weeks to get the red or green versions, which are currently the rage with our sons and daughters fighting over in the sandbox. So a TA11E- A was the choice of optic for this evaluation as a result of this very specific process of elimination.

the crystal clear view presented by this Trijicons amber chevron and 800-yard BDC

The optics on my Nikon digital camera just don’t do justice to the crystal clear view presented by this Trijicon’s amber chevron and 800-yard BDC


The standard Trijicon ACOG package comes with an assortment of case candy, including a really neat hard plastic Pelican travel case, a super-functional lens pen cleaning accessory, a Scopecoat protective cover to keep dust and debris from your optics when mounted on your weapon, plus a host of other things, such as an operator’s manual, summary brochure, warranty card, a lens pen usage instruction card, revised sight-adjustment procedures and a Trijicon decal.

My TA11E-A ACOG was equipped with a standard heavy-duty TA51 flattop mount that allows it to be almost surgically attached to my Rock River LAR-8’s T-marked A4 flattop upper. This format enables it to be mounted in the same T-section of the upper each and every time in an attempt to keep your zero as sacrosanct as possible and to also put it in a known spot to maximize personal sighting and eye relief.

You want a rock-solid connection from your sight to your weapon with no shimmy, rattle or shake, even after dropping it on the ground multiple times? Well this is as good as it gets. The twin thumbscrews give it a super solid and relatively quick connectivity and disconnect, which is spread across the 3½-inch-long base of the forged aluminum TA51 mount. The screws also offer slot cutouts in the plastic end caps so you can employ the blade of a standard slotted screwdriver to really crunch these thumbscrews down for a semi-permanent connection, if desired.

My first look through the 35mm x 3.5X magnification of the TA11E-A can be described in only one word: “wow!” What a picture. Clean, bright, crisp, clear… and with that nasty little dual-lit amber chevron ready to mark any target of choice, glowing brightly day or night, dawn or dusk.

The secret to the chevron’s “always on” status is its ability to draw illumination from two super-reliable light sources: the sun, the center of our solar system and an abundant resource since the dawn of time, which is gathered in the ACOG’s unique fiber-optic light collector located on top of the sight body; and via an internal self-luminous tritium phosphor lamp. The tritium component has a useful life of over 20 years, so you should be able to range many targets in future seasons after acquiring one for your personal kit.

The chevron and bullet drop compensator range scale seemed micro-sized at first, but as I sighted in different targets at varying distances (25, 50, 100 and 200 yards), my eyes quickly adjusted to the scale of the reticle pattern versus the targets at hand and all was good to go.

This dual-illumination technology, originally developed for the US military and proven thousands of times in combat all over the globe, allows the aiming point to be /always/ illuminated. Tritium illuminates the chevron (or donut, horseshoe, crosshairs, triangle, etc.) aiming point in total darkness, while the fiber-optic array increases reticle brightness according to the ambient light levels of your environment. This automatically balances aiming-point brightness with shooting conditions, allowing the Bindon Aiming Concept (BAC) to function at max efficiency.


Simply put, the Bindon Aiming Concept, named after Trijicon’s founder Glyn Bindon, employs a “both eyes open” aiming technique that combines traditional long stand-off marksmanship capability with the ultimate in close-quarters transitional aiming. According to the Trijicon folks, this is accomplished by allowing two-eye-open aiming in a magnifying optical system by taking advantage of the “glowing” reticle (sort of like that nasty laser cannon on the Predator’s shoulder harness kit).

This bright aiming reticle, which is illuminated by both the external fiber optic systems and the internal tritium phosphor lamp, is a significant improvement over red dot reticles or other collimator sights and enhances the speed and accuracy at which the eye can track and aim the reticle. The simple substitution of a bright red dot (or a chevron) for the usual crosshairs found on other types of scopes makes it very easy to keep both eyes open with the Trijicon ACOG.

During dynamic movement, the scene through the telescope blurs because the image moves more rapidly due to the magnification of the optics. The one eye sees the bright dot against the blurred target scene, so the brain picks the scene from the unaided/unmagnified eye. The shooter swings the weapon towards the target while perceiving the dot indicating where the weapon is pointed. As soon as the weapon begins to become steady in the target area, the brain switches back to the magnified view.

The BAC principle is automatic, it happens instinctively. It does take some practice, but once your eyes and brain are both working on the same page with your magnified optics, it’s a heck of a system and produces impressive results.


And how did this little mil-spec accessory add to the shootability of my relatively new Rock River LAR-8? Well, let’s just say that I am so spoiled, it’s really hard to go back to using open iron sights. The groups that I was shooting with standard grade current mil-spec and historical mil-surp 7.62×51 NATO 147-grain FMJBT ammo were truly impressive. My shot groupings were twice as tight as when shooting with the Rock River’s high-quality ½-inch MOA iron sights. Yet, that was only half the story.

Target acquisition with the Trijicon TA11E-A was just about instantaneous, and at any range. See the target…put the chevron on the target…squeeze the trigger…hit the target, each and every time. By the numbers, it was that simple to become an “expert” shooter just by adding this ACOG to the flat top rail of my Rock River. In contrast, the sighting, aiming and shot selection process using the open iron sights required a lot more deliberation, and was much slower in comparison.

I had target hits using current mil-spec M80 ammo that were literally touching each other like small clover leafs at 100 yards. I don’t know if that was luck, or the 1-MOA quality of the Rock River’s 1:10 twist S/S barrel, or the exceptional clarity and 3.5X magnification of the Trijicon TA11E-A ACOG or the hand of God working in a strange and wonderful way. Or maybe a little bit of everything.

Current mil-spec 7.62×51 NATO ammo from both Federal (Lake City) and Winchester has a 2-to-3 MOA accuracy standard for 100 yards, so to have these projectile hits touching each other on the target at that range was great to observe and made for a very “feel-good” reassurance that I had the right tools for the job working in harmony to achieve a single mission objective.

Right out of the box, the sight required some adjustment as can be expected, but it was no big deal. All it took was about 10 minutes of shooting a few spotters at 100 yards (about 20 rounds downrange total), checking the relationship of the POA (point of aim) to the POI (point of impact) with my spotting scope, making the necessary adjustments to the windage and elevation knobs located on the top (elevation) and starboard (windage) sides of the ACOG, and this girl was totally ready to rock.

With Trijicon’s 35×3.5 series of ACOGs, one click is equal to ¼-inch adjustment at 100-yards, so if you need to move the POI one inch at this range, it will require four clicks in the appropriate direction to make it happen. POA/POI repeatability with these zeroes after intentionally taking the ACOG on and off the Rock River’s flattop upper was good to go as long as I mounted the ACOG back in the same T-marked position on the upper. The detailed operators’ manual had a neat section on estimating hold-overs for windage and for ranging moving targets that is definitely a must read.


Built with a solid, military-grade forged 7075-T6 aluminum alloy housing (the same proven material used to construct the M16’s upper and lower), the housing is precision machined and hard anodized giving it a rock hard surface. The fiber optic housing is manufactured from GE Lexan Polycarbonate material, due to its proven impact resistance, light transmission and optical qualities. The fiber optic tube is set into a protected channel in the upper sight’s aluminum housing for additional security and is attached via a roll pin in the forward section of the sight for integral stability. The ACOG’s multi-layer coated lenses ensure peak optical performance and a large exit pupil allows maximum eye latitude.

The Trijicon TA11E-A ACOG is so advanced that the user does not need to make any special adjustments between shots at different ranges, since ranging is already built into the parallax-free reticle once the initial zero has been established at 100 yards. I was really impressed with the precision craftsmanship of this Trijicon ACOG that featured matching engraved serial numbers on all of the component parts, which is a nice touch.

The MSRP of the TA11E-A complete with the sturdy TA51 forged aluminum flattop mount is $1,428, with a street price usually a few hundred bucks less, so this Trijicon is not a cheap date and will probably cost as much or more than the rifle you intend to mount it on. However, backed by a lifetime warranty, this robust made-in-USA ACOG is one of the finest purpose-built sights in the world at this moment in time for accomplishing its intended objectives and it will make a great rifle even better, as demonstrated by the morphing of my Rock River LAR-8 from a marginal tack driver into a designated squad marksman sniper’s tool.


Trijicon TA11E 


Magnification: 3.5x
Objective Lens Size: 35mm
Bullet Drop Compensator: Yes
Length: 8″
Weight (oz): 18.5 (Mount Included)
Illumination Source: Fiber Optics & Tritium
Reticle Pattern: Chevron
Day Reticle Color: Red, Green or Amber
Night Reticle Color: Red, Green or Amber
Caliber Calibration: .308 Cal (7.62mm)
Bindon Aiming Concept: Yes
Eye Relief (in): 2.40
Exit Pupil (mm): 10.00
Field of View: 5.50 Deg
Field of View @ 100 Yds (Ft): 28.90
Adjustment @ 100 Yds (Clicks/In): 4

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