The Trijicon ACOG is a legendary optic among many servicemen who have relied upon its durability and versatility during combat.  While I am lucky to count myself among that group, my time spent overseas was spent with the venerable TA01 which has been surpassed time and time again by more advanced offerings from Trijicon.  While researching optics I came across what seems to be a unique collaboration: a Trijicon ACOG using a non-Trijicon reticle.  In this case, it’s the ACSS reticle from Primary Arms.  While I can only speculate as to why Trijicon opened up its flagship optic to using a non-OEM reticle, this seems to be a one-of-a-kind partnership.

Given that we’re essentially looking at two products here, I want to cover some of the basics on each before diving into how they work as a whole.

First, the ACOG.  The Advanced Combat Optical Gunsite is a compact, fixed power scope of the “prismatic” design variety.  Rather than using a series of lenses (and a long tube), a prismatic scope uses a glass prism to focus the image.  The result is a much more compact scope, though one with a generally shorter eye relief (1.5″ here).  There are a variety of ACOG models with varying reticles, magnification and even power sources.  The specific model shown here is the TA31-R-ACSS.  It has 4x magnification in the aluminum alloy body, with the reticle being illuminated both by (mildly) radioactive tritium as well as a fiber optic cable.  This ACOG is much shorter than traditional scopes and weighs in at 9.9 ounces.  Water-proof, shock-proof and damn near Ranger-proof, the ACOG is the king of the hill regarding short-to-mid-range combat optics.

The Advanced Combined Sighting System is the patented reticle provided by Primary Arms.  It combines a number of features, intended to provide combat accuracy at extended ranges with little loss of speed.  The four areas of focus are:

• Bullet drop:

When shooting up close, one finds the aiming chevron surrounded by anattention-grabbingg horseshoe, both illuminated.  This is the section of the reticle intended for use in CQB distances.  Below that is the “ladder”, the bullet-drop compensation table.  While calibrated for M193 ammo through a 14.5″ barrel, slight changes in zero distance can provide “close enough” accuracy in other bullet weights of 5.56mm as well as 5.45mm and 7.62 nato.

• Windage

Fairly simple, the dots represent a 5mph wind’s effect on an M193 round at the given ranges.  If the wind is stronger, weaker, or not at full value, simply adjust as needed.  Combat accuracy isn’t the same as precision accuracy.  Getting really close on the first round then adjusting for a follow-up hit is just fine for a rifleman at 712 yards in the wind.  Give the shooter the tools to start out on it or near it and let him do the rest.

• Ranging

We’re given two methods of range estimation here.  Target height or target width.  Using the average human torso width of 18″, one can do some simple dividing and multiplying to work out an approximation of range.  Or, using the ACSS, you can simply be thankful the horizontal bars from 400 yards and down match up to an 18″ width.  As shown, the horseshoe is used for 200-300 yard ranging, which isn’t as needed since range estimation errors at that distance are their smallest and bullet drop isn’t nearly as severe.

Using average human male height of 5’10”, the shooter can easily put their target into the ranging bracket on the right (feet on the bottom line) and see where they line up.  Again, if they look taller or shorter than 5’10”, adjust accordingly.

• Leads

As per the ACSS insert that came with the ACOG manual, these lead calls are best used between 100-300 yards.  This isn’t intended to give the mathematical solution to every possible angle or movement speed.  The ACSS reticle simply and quickly lets the shooter put a hit on a target moving perpendicular to the shooters line of fire, either walking or running.

The ACOG’s first iteration created a legend.  The ACSS reticle has the shooting world abuzz with its efficient, effective communication of data.  While I’ve had a few range trips with the ACOG/ACSS, I want to get the round counts way up before I drop my final review.  The ACOG is a premium optic with a premium price point of $1277, thus potential buyers are deserving of as much info as they can get their hands on before making a purchase choice.  The ACSS reticle equipped ACOG is a Primary Arms exclusive, unavailable through other retailers.  So far, it’s just as good as the ACOG I remember from my days in 2/75, with upgraded illumination and aiming device.  Head over to the Primary Arms website here and check it out!  Full review inbound.

-Rex Nanorum