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Trijicon ACOG Considerations [2006-01-01]

(Originally written in 2006, updated to add information on the TA33)

I purchased my first Trijicon ACOGs in 1998, a TA11 with red donut reticle, and a TA01NSN with crosshair .223 ballistic reticle. Since that time I have owned numerous ACOGs to include several TA11's, TA01's, TA01NSN's, TA31's, and the TA33.

The TA01 and TA01NSN have a reticle that is black in daylight and a red or amber tritium that can be seen in low light or no light conditions.

The TA11, TA31, and TA33 all have amber, red, or green reticles that are powered by both fiber optic and tritium. Thus the amber, red, green reticle can be seen in both daylight and low light or no light conditions. I find I am quicker with the dual illumination (fiber optic and tritium) reticle because it can be seen during daylight hours and I find that I can pick up a red reticle much faster than I can pick up a black reticle.

ACOG and reticle photos are property of www.trijicon.com, used with permission.

TA11 3.5x35: eye relief 2.4" - Field Of View at 100 yards is 28.9' - 14 ounces - 8" in length

Dual Illumination Red Donut .223 Ballistic Reticle:

TA33 3x30: eye relief 1.9" - Field Of View at 100 yards is 19.3' - 11.64 (with factory mount) ounces - 6.10" in length

Dual Illumination Amber Chevron .223 Ballistic Reticle

TA31 4x32: eye relief 1.5" - Field Of View at 100 yards is 36.8' - 9.9 ounces - 5.8" in length

Dual Illumination Green Horseshoe .223 Ballistic Reticle

TA01NSN 4x32: eye relief 1.5" - Field Of View at 100 yards is 36.8' - 9.9 ounces - 5.8" in length

Center Tritium Illumination Amber Crosshair .223 Ballistic Reticle

Per the Trijicon website it states that the TA01, TA01NSN, and TA31 all have an eye relief of 1.5". I have found this to be pretty accurate. Trijicon shows the eye relief on the TA11 as 2.4". In my experience the I have found that the eye relief on the TA11 is closer to 3".

Eye relief has much more utility than keeping the scope from hitting your face when the scope is mounted on a rifle that has heavy recoil. Eye relief aids in locating targets quicker (when engaging multiple targets at various distances) and getting on target quicker (because head position and scope shadow are not as critical with longer eye relief).

While I find the weight and size of the TA01NSN and the TA31 almost perfect for a fixed 4x optic, my main complaing about the TA01NSN and the TA31 is the short eye relief. Short eye relief is not a big issue if all your shooting will be done from a bench, but the short eye relief on the TA01NSN and TA31 ACOGs really expose themselves when running and gunning and shooting from non traditional positions. Note the short distance from the shooter's eye to the back of the TA01NSN ACOG (1.5" eye relief) from this picture from a LMS Defense carbine course:

I have owned both the TA01NSN and the TA31 and used both for shooting local run and gun rifle matches. I prefer the TA31 because I'm quicker with fiber optic powered daylight illuminated reticle in the TA31 (also found in the TA33 and TA11). Due to the short eye relief on the TA01NSN and TA31, I found it hard to locate targets down range when shooting at several targets at varying distances down range.

Another issue I encounted with a scope that has short eye relief is head position is very critical and a shooter can waste valuable seconds obtaining the correct head position when changing positions rapidly or shooting from unconventional positions. At most run and gun rifle matches, the shooter will shoot from one position, then have to run to the next barricade or shooting position, get into a standing, kneeling, squating, sitting, prone, or unconventional position, and start engaging targets down range. With the TA01NSN and TA31, after moving from one position to the next, I would often have to take an extra second or two to adjust my head position so I could obtain the proper eye relief. With the more generous eye relief on the TA11, I don't have this issue. With the TA11 I get into position, put my face on the stock, and can immediately see down range through the TA11 without any eye relief issues.

I shoot with both eyes open. When using the TA01NSN and TA31 in matches, often times during long range stages I found myself taking my face off the stock, and having to look over the top of the TA01NSN or TA31 to locate the next target. I have shot the same courses of fire with both the TA31 and TA11 back to back, I found the TA11 much quicker in locating targets down range, and I wasn't searching for targets or having to look over the top of the TA11 to locate the next target (steel targets at a local match, positioned from 175 yards to 425 yards):

(Photo Credit - Zak Smith Demigod LLC. - Pic used with permission)

(Photo Credit - Zak Smith Demigod LLC. - Pic used with permission)

Per the spec sheet listed on Trijicon's site the TA11 has a Field Of View at 100 yards - 28.9'. The TA31 has a Field Of View at 100 yards - 36.8'. The TA31 has approximately a 8' wider field of view at 100 yards. In theory a shooter should be faster and be able to see more with the optic that has a wider field of view. In this case the exact opposite was true. Due to the short eye relief of the TA01NSN and TA31 the shooter's face is closer to the ACOG and he can't see around the ACOG, the shooter's non-magnified field of view is somewhat limited. With the TA11 the shooter's face is further away from the ACOG and he can see around the ACOG much better, thus increasing what he can see in his non-magnified field of view.

In the pictures below note how much distance is between my eye and the back of the TA11, then compare this to the eye relief of the TA01NSN shown earlier in this article:

(Photo Credit - Zak Smith Demigod LLC. - Pic used with permission)

(Photo Credit - Zak Smith Demigod LLC. - Pic used with permission)

The barricade is so low I have cant my carbine just to be able to see the target. I would have been much slower and in a much more uncomfortalbe position if I was using a TA31 with 1.5" eye relief. Just another example of how important eye relief can be:

(Photo Credit - Zak Smith Demigod LLC. - Pic used with permission)

My preference is for the TA11, as it has the same features as the TA31 with longer eye relief. The only down side to the TA11 is that it's larger and heavier than the TA01NSN and TA31. I prefer the smaller size and weight of the TA31, but the eye relief issues are why I use the TA11. What is writen above is not ment to take away anything from the TA01NSN or the TA31, both are excellent mid-range optics, but many people underestimate the importance of longer eye relief.


I often get asked what reticle I use and why. Since 1998, I have always used the red donut reticle. I have tried both amber and red reticles and I have used the donut, chevron, triangle, and crosshair reticles.

I have used amber colored ACOG reticles in the past, but have had problems with the reticle being difficult to pick up on some backgrounds. An example of time when I've had problems seeing the amber reticle: a cardboard target at 400 yards, a target that was mixed in weeds (from the pics above you can see how an amber reticle could blend in with the prarie grass), a card board target close to a dirt berm at distance, etc. Red stands out much better to my eyes than amber and provides more contrast against everything I have come across with the exception of orange targets. Nothing in nature is red or close to red. On the other hand, amber doesn't provide enought contrast for me against items that are tan or light brown in color.

The reason I prefer the red donut reticle is because every optic that I have that has an illuminated reticle has two things in common, the illuminated reticles are all red and they are all round. This commonality in my optic reticles makes transitioning from one optic to another much easier.

With only a couple exceptions most of the reticles (Aimpoints, TA11s, etc.) all have close to a 4 MOA dot. If I'm shooting at distance I don't have to think too much about hold overs.

-At 50 yards, center of the dot = point of aim / point of impact.

-At 100 yards, top of the dot = point of aim / point of impact.

-At 200 yards, center of the dot = point of aim / point of impact.

-At 300 yards, bottom of the dot = point of aim / point of impact.

-At 400 yards, hold the dot just above what you want to hit = point of aim / point of impact.

No matter if I'm using an ACOG or an Aimpoint, my hold overs are close to being the same.

I have eighteen AR-15's (15 Aimpoints, 2 ACOG TA11s, and a Leupold MR/T). I can pull anyone of them out and everything is very close to being the same. My Leupold MR/T 1.5-5x is the only optic that deviates from the rest, but it's so simple it's hard to screw up.


In late 2008 I received a TA33 for test and eval. I only had the TA33 for a short period of time, so my opinion of the TA33 is based on this short T&E.

I loved the weight and size of the TA33. Clairity of glass was outstanding, eye relief was so generous that I had the TA33 mounted toward the forward end of the flat top receiver. Field of view was outstanding because I was able to mount the TA33 far foward enough and the TA33 was such a compact package that I could see around the TA33 very easily, both on the right and left side of the ACOG. This made transitioning from one target to the next very easy. The field of view of the TA33 is 19.3' at 100 yards, which is 9.5' smaller field of view than the TA11, but do to the extremely generous eye relief the shooter can easily see everything around the TA33, which increases his non-magnified field of view.

My complaints about the TA33 were the fact that it only came in a chevron reticle (I prefer the donut reticle, but Trijicon recently released a horseshoe reticle that I wouldn't mind trying) and the mount had the optic sitting to low and it effected my head position in a negative way. I want to be able to snap the gun up and have the reticle on target without having to adjust my head position. With the TA33 I had to push my face into the stock to get proper cheek well for the height of the TA33. That being said, I was using the factory TA33 mount and I was using the TA33 on a carbine that had a Magpul UBR stock, which has a slightly raised cheek piece. Either the mount or the UBR or both may have been factors in the TA33 sitting too low for me. I only had the TA33 for a short period of time and wasn't able to mount it on several different carbines.

I was impressed enough with the size, weight, and long eye relief, that I may be giving the TA33 another try now that Trijicon has released the TA33 with a red horseshoe (circle / dot).