by Ilya Koshkin

I have had a reasonable familiarity with the Trijicon ACOG for quite a while now, but I never really bothered to do an article on one since the bulk of my interest in AR scopes was with the low range variables. Indeed, in terms of flexibility and capability, good quality variables are the way to go. However, they are almost invariably heavier than I like and, often, bulkier than I like. There are some exceptions, of course, with Leupold VXR 1.254x20 coming to mind, but if I choose to go with a variable, I want true 1x on the bottom.

A switch power scope like Elcan Specter DR 1x/4x or IOR 1x/4x Pitbull is an interesting option, but they are a bit heavy weighing well in excess of 20 ounces. Besides, I like the idea of two independent sighting systems: if one goes down, I want the other one uneffected.

I am a precision guy at heart, so even on lightweight ARs I like to have some amount of magnification available to me. Hence, the next logical step was to consider the ACOG and similar compact fixed power scopes. An added benefit is that most of them can be paired with a miniature red dot. However, for this article I looked at three similarly configured sights with no additional accessories.

For comparison purposes, here are two pictures, one with the Trijicon ACOG mounted on one of my ARs and another that shows a rather conventionally sized 16x24 on the same rifle. Note the difference in size.

Compact AR Scopes

Compact Ar Scopes 1

Here is a spec table for the three scopes I looked at (in bold) along with a couple of others:

Compact Ar Scopes Table 1

All three of the scopes I looked at are 4x in magnification. The reason I picked 4x is that the HAMR is only available as a 4x24. Both Trijicon and Elcan offer other magnifications.

Here is a brief summary of what I found with these three scopes:

  • Optically, Elcan walks all over the competition, and it is easily the best one of the three for precision shooting, while being very capable for everything else. I really like the illumination scheme on the Elcan.
  • HAMR offers additional mounting flexibility, which came very useful for me, and is the lightest of the three once you actually weigh the scopes.
  • I do not particularly care for the reticle in any of these scopes, but Elcan gave me the most precision, while HAMR was the fastest. With the ACOG, I should have gotten the circle dot reticle which is similar to the HAMR. The holdovers are not especially useful with any of them once you get past 400 yards.
  • If you are getting older and your eyes are not what they used to be, the HAMR is the only one of the three with adjustable eyepiece focus.
  • The short eye relief of the ACOG made it much harder to get behind quickly and comfortably than the other two.

Now onto the details…

The rifle I used to run most of the tests on these scopes is very light. It has a pencil thin melonited barrel from Voodoo Innovations, carbon fiber handguard from Lancer and ACE ultra light stock. It is my SHTF rifle, so I insist on having two independent sighting systems on it . I already have a set of backup iron sights (BUIS) on it, so I have to mount the scope a little further forward than I could have without the BUIS. Couple that with a fixed length stock and what you get is issues with eye relief.

Compact Ar Scopes 2

I did bring another lower half with me that is nearly identical, except for having a collapsible Vltor Imod stock. That rendered the ACOG almost usable and made Elcan a perfect fit. A lot of the tests I ended up doing with the collapsible stock lower half to be fair to all three scopes.

Compact Ar Scope 3

Both the ACOG and the HAMR come with a flat top adaptor, but the ACOG adaptor can only be mounted one way, while the HAMR has a couple of positioning options that came really useful.

Here is a picture that shows the approximate location of the oculars of the three scopes sidebyside:

Compact Ar Scopes 4

Since the ACOG’s eyerelief is more than an inch shorter than that of Elcan and Leupold, it was difficult to use with a fixed length stock and BUIS in place.

The SpecterOS comes with a QD mount (ARMS levers) and external windage and elevation adjustments. I am not a huge fan of ARMS levers, but best I can tell this iteration is pretty sturdy and gave me exactly zero problems. Perhaps more importantly, the Elcan returned to zero sufficiently for me to not see a perceptible difference in POI.

Both the HAMR and the ACOG have the regular thumbscrews with two crossbolts on their mounts. The crossbolts on the ACOG adaptor are round, while the HAMR crossbolts have flattened sections. The HAMR also came back to zero well, if I was somewhat paying attention to even and consistent screw tightening. The ACOG shifted zero a fair bit more, but there are many better aftermarket options for an ACOG mount, if you need a quality QD mount.

In terms of mechanical qualities, all three scopes look like they can take a beating. I suppose the fiber optic collector of the ACOG is a weak spot, but there are LED powered versions of the ACOG, so you do not have to get the fiberoptic one if you do not like it. I did not have any durability issues with any of these and they held zero without any concerns on my part.

Compact Ar Scopes 5

If push comes to shove, the Elcan’s elevation adjustment allows for dialing in shots and I played with it a little. It worked surprisingly well. The large knurled adjustment ring under the scope body needs to be unlocked using a coin or a knife blade or a screw driver (or a sturdy thumbnail), after which it can be easily rotated. Of these three scopes, the Elcan is easily the best for precision shooting so experimented with it in that capacity with surprisingly good results. There is a lot to be said, I suppose, about nicely optimized designs even with moderate magnifications. I could easily use this sight to the extent of the range of the 5.56x45 round and would not have any issues using it on a precise semiauto 7.62x51 either.

Ultimately, all three of these scopes are designed to be used primarily with holdover reticles. From left to right: Elcan, Trijicon, Leupold

Compact Ar Scopes 6

To my considerable surprise, the ACOG’s chevron reticle did not agree well with me at all. I’ve used chevrons in a variety of scopes over the years and liked them. However, that was usually in different designs. In the ACOG, I suspect that the Horseshoe Dot reticle would work much better for me. Please note that in terms of visibility, all three reticles were quite visible (much more so than in these small pictures).

All three of the reticles have holdover marks out to 800 yards with rudimentary "shoulder width" ranging feature based on the width of the holdover hashmark. That is not the most precise way of figuring out distance and I have never been able to make it work beyond 300 yards or so. The Elcan reticle does have a chokestyle rangefinder on bottom left which works much better for me.

The Leupold reticle is designed with NATO standard M855 ammo in mind. Ditto for the Elcan, although neither mentions barrel length. The ACOG reticle (except for the TA01NSN model) is calibrated with a 55gr 5.56 bullet out of a 20” barrel.

The only problem is that I use 77gr and 75gr ammo (similar to Mk 262) virtually exclusively.

Here is how the external ballistics compare (typically) in terms of drop and wind, both in milliradians (courtesy of JBM Ballistics website):

Webyshops Compact AR Scopes 7

The drop is pretty close, especially if you stay within 400 yards, but the windage is not.

Optically, the comparison turned out to be far simpler than I had expected: the SpectreOS walked all over the other two scopes with HAMR edging out the ACOG for second place. In all fairness, all three scopes performed better than I expected, but the ACOG is the oldest design here and it shows.

I stretched the legs of the rifle the scopes were sitting on and as far as precision shooting goes, the Elcan has a clear advantage over the other two scopes here. I could resolve better with it, contrast was better and the scope was easier to get behind.

In terms of actual usability, the difference was also considerable with the Elcan and Leupold being very easy to get behind and the Trijicon turning out to be a bit tricky. I suppose it is the combination of short eye relief and small ocular lens.

The reticle illumination scheme was also different between these three sights, but before I get into that, it is worth mentioning that Tijicon offers the ACOG with a variety of different illumination schemes: tritium only, tritium with fiber optics, LED only, etc. The version I looked at is tritium with fiber optics and I specifically chose this one to see how I like it. I know full well that I like the ACOG with a battery powered LED, but the fiber optic version was interesting to look at.

As it were, I found all three illumination schemes to be quite serviceable. The Leupold and Elcan have battery powered illumination with the Leupold offering a conventional turret on the right side of the scope body, It has sufficient dynamic range for both low light and bright light shooting and proved to be pretty fast in use. The illumination is easily day visible even on bright California days.

The Elcan illumination is also controlled by a rotary turret except it sits on the left side of the scope body, which works quite well on ARs. When I needed to make a quick adjustment on the HAMR I had to reach over the scope with my left hand, since ARs are designed to be run with the left hand. When I tried shooting with a support sling, it was easier to run the HAMR, since I was doing it with the right hand. The left arm was locked in place by the sling.

I wonder why the reticle brightness adjustment is not on top of the scope body. A low and wide turret there would be convenient for operation with either hand. It might interfere with topmounted mini red dot sights though.

The SpectreOS illumination differs from the HAMR in another significant way: it has two modes depending on which direction you rotate the turret two away from the OFF position. The bright light mode illuminated the tiny center crosshair and is visible during the day. The low light mode illuminated the whole reticle pattern, but faintly enough to keep you eyes night adjusted. Both modes have several brightness levels. I found the setup to be well conceived and well executed. In low light mode, I could executed precision shots in very dim lighting and the generally excellent optical quality of the Elcan definitely helped as well. Here is a look at the operation of the Elcan illumination controls.

Webyshops Compact AR Scopes 8

The ACOG illumination has some strengths and some weaknesses. The biggest strength is also the biggest weakness: it is always on. It is bright and easy to use. It is fast to pick up as well. However, if the lighting conditions where you are differ significantly from where you are aiming, it does not always work all that well. Aiming at a bright spot from inside a dark room was not optimal, while aiming from a brightly lit area into shadows had other set of problems with a very overpowering reticle. Still, those are fairly extreme conditions and if you do not like this illumination scheme, Trijicon offers a variety of illumination options.

Here is how I rank the different attributes of these scopes:

  • Optical quality: Elcan > Leupold > Trijicon
  • Mechanical quality: Tie
  • Ease of use: Elcan=Leupold > Trijicon
  • Veratility: Elcan Leupold > Trijicon

For a lightweight carbine, the HAMR is probably the best option owing to its light weight and overall good performance.

If you can live with four extra ounces, the Elcan SpecreOS is a more refined and versatile scope with the best optics of the bunch.

If you need ocular adjustment in your scope, the Leupold is the only game in town.

Having played with these 4x scopes, I found that while I can use them with good speed, adding a miniature red dot is a good idea. All three have provisions for mounting a red dot and I will likely do so in the near future.