Thoughts on Optics Selection

Like barrels, triggers, and any number of “choices”  on an AR-15, there are a lot of options out there for optics. There is also a lot of misunderstanding. I want to take a moment and discuss some thoughts on optics selection. There are already some really great guides out there, but they focus more on particular classes of optics. I will link to them as appropriate since I don’t feel the need to reinvent their excellent work. Rather, I want to look at a broader picture of why you might choose one class of optics over another, and how you might best employ them.

As a refresher, I have two fundamental rules for buying any firearms-related gear.

  • Let the mission dictate the configuration
  • Buy once, cry once

Now, let’s get to it.

The Everyday Marksman’s Five Classes of Optics

Zak Smith wrote a very detailed article for Shotgun News back in February of 2008 detailing his thoughts on fighting optics. In short, he categorized optics into three basic types: CQB, DMR, and SPR. Each type is best suited for different engagement ranges and weapon employment method. However, much has changed in the world of rifle optics since that article was written in 2008.

I break optics into five general classes:

  • Class I: Iron Sight Replacements
  • Class II: Low Powered Fixed Magnification
  • Class III: Low Power Variable Magnification
  • Class IV: Mid to High Magnification
  • Class V: Digital Hybrid

I derived these categories by using Zak Smith’s typography as well as the US Army’s
phased plan of optics evolution (previously mentioned as part of an Army conference back in June). Most shooters are reasonably familiar with the first four categories; the fifth may be news- but it is the future.

Screen Shot 2015-06-20 at 12.30.51 PMLet’s break down each of these classes.

Class I: Iron Sight Replacements / CQB


This class of optic is probably the most popular on the market, typified by the Red Dot Sight (RDS). Characteristics of Class I optics include zero magnification, parallax-resistance (not necessarily parallax-free), and a focus on speedy sight acquisition. This class of optic simplifies the sight picture by removing the need to align the front and rear sights with the shooter’s eyeball. The shooter keeps both eyes open and focuses on the target; the ‘dot’ is projected onto that same plane. From there, the task is simply to put the “dot” on the desired point of impact and squeeze the trigger.

I think of Class I optics as better versions of the M16A1 iron sights. You set your zero for a specific distance, usually a desired point blank zero, and then go fight. Use holdovers as necessary for anything outside of that point blank zero range. This class of optic excels from bad breath distance out to 250ish meters. They are lightweight, compact, and some can be left on for years before the battery needs to be changed. Some models do not have batteries at all, and will use fiber optics and tritium for illumination.

This class of optic rose to prominence during the conflict in Iraq and the intense CQB/urban operations it entailed. These optics are fantastic for use against moving targets or any situation where the speedy acquisition of a sight picture is the top priority. If you regularly shoot from unconventional positions where a proper cheek weld is difficult or unlikely, then these optics are king of the hill.


Class I optics are the only ones capable of co-witnessing with iron sights. That means that a shooter can attain a proper sight picture through the rear sight aperture and look through the optic to the front sight, and have all four elements (front sight, aiming point of the optic, rear sight, and the eyeball) all align simultaneously. This is valuable if the optic ever fails- the shooter can still use the iron sights without issue while leaving the optic in place.

While Class I optics are a great choice for a general use defensive weapon, they do have limitations. Shooters with uncorrected astigmatism may see imprecise blobs or clusters rather than nice crisp red dots (I find this is worse on battery powered options). The lack of magnification means that this type of optic is not ideal for observation tasks, and will be of little help for differentiating among targets or identifying a target in relation to its background. Furthermore, Class I optics are not designed to have their zero easily adjusted to account for various distance or windage scenarios. It’s all Kentucky Windage, all the time.

The New Rifleman has a very nice guide to Red Dot Optics and their use, so definitely check it out for more specific information.

My preferred Class I optics are Aimpoints (M3, M4, PRO, CRO, and T2), EOTechs (XPS series), and the Trijicon MRO (Note: With the recent revelations about EOTech’s performance issues in certain temperature ranges, I’m a bit more hesitant to recommend it for any purpose). There are other options out there at varying price points, but that is where the second law comes into play. If you plan on trusting your life to an optic, do not go cheap. The ones listed above are all extremely tough, and will handle more abuse than most people will probably ever throw at their rifles.

Class II: Low Powered Fixed Magnification


This class of optic is best typified by the ACOG. There are many others on the market, such as my ELCAN SpecterOS (pictured), the Leupold HAMR, IOR Valdada QR-TS, and the Zeiss ZO 4x30i. This class of optic  gained traction during the US Army’s Advanced Combat Rifle trials in the 1980s. Notably, Trijicon teamed with AAI to submit an early version of the TA01 ACOG on their rifle entry and ELCAN presented an early version of the C79 with Colt’s submission. While the replacement rifle never came to fruition, the optics did. Class II optics have grown more popular over the years as militaries have recognized the value of ruggedized magnified optics for general military use. They are typically compact, relatively lightweight, rugged enough to put up with the abuse infantry life, and offer huge marksmanship benefits over iron sights.

I would venture to say that Class II optics embody the skill set of the last generation of riflemen, before the focus turned to vehicle-borne operations and CQB. Class II optics truly reward proper execution of marksmanship skills, and they excel at the medium ranges that militaries have historically operated in (think 50 to 500 meters). The use of this type of optic assumes that the shooter will have time to see a target, move to appropriate cover, identify the target as a threat, and then apply marksmanship fundamentals to eliminate the threat.


The reticles in these optics usually have some form of rangefinding stadia and a calibrated bullet drop compensator (BDC). These are intended as field-expedient methods of estimating where hits will land and not intended for true precision shooting. The BDC reticles are usually calibrated to a specific bullet moving at a specific velocity under specific environmental conditions. Deviating from these standards means that the BDC will not be correct, but should still be “close enough.” This type of optic lends itself very well to Sniping 4th Generation (S4G) style shooting.

Class II optics are limited by the characteristics inherent in the bending of light to create magnification. That means that the shooter must have a consistent cheek weld to account for eye relief, parallax, and the exit pupil of the optic. Incorrect alignment results in poor sight pictures and missed shots. Relative to Class I optics, magnified optics are slower to move from target to target since the eye has to readjust and refocus as targets come into view. Class II optics, like Class I, do not usually allow for easy zero adjustment in the field for “dialing” shots. They are meant to be zeroed and left alone. Again, it’s all holdovers, all the time. Lastly, Class II optics are typically fixed at a certain parallax setting and do not have diopter adjustments to account for different people’s eyes.

A “horseshoe” fiber optic powered reticle on an ACOG
The “daylight” turned up to maximum power on my ELCAN SpecterOS
The “low light” setting, illuminating the entire reticle

Some of the more modern Class II designs indlue methods of illuminating the reticle. This works both for illuminating the aiming point at night, but also helps speed up shooting during the day. Brightly illuminating the center of the reticle helps “draw the eye” and give it something to focus on. This is the same concept as the old Armson Occluded Eye Gunsight (OEG), a 1970’s era South African precursor to Class I optics (Trijicon actually got its start as the importer for Armson). If the shooter keeps both eyes open and allows the brain to superimpose the illuminated reticle in front of one eye over the wide field of view of the other, it can be almost as fast as a Class I optics. Note that using magnified optics in this fashion can be affected by phoria, the intensity of which varies from person to person depending on eye dominance and other factors. Phoria is how far the alignment is off between each eye when focusing on a target. When I shoot using this OEG method, I know I will actually be aiming about 4-6 MOA to the right of the target when I switch focus back to my right eye.

Class II optics are best suited for practical marksmanship and general dismounted shooting, where a balance must be struck between speed and accuracy at a variety of distances (known and unknown).

My personal picks for Class II optics include the aforementioned Trijicon ACOG line (particularly the TA-11, TA-31, TA-33, and TA-44), ELCAN SpecterOS 4x, and Leupold HAMR. Note that all of these are fairly expensive, nearly double the cost of a quality Class I optic. Remember, you’re not just paying for magnification here, you’re paying for the durability.

Class III Optics: Low Power Variable


This class is fairly new and was developed to bridge Class I and Class II optics for competition. They will usually have some way to switch between 1x (“No” magnification) and some number greater than 1 (usually 4x or 6x). The traditional method is by moving the optics internal lenses via an exterior mechanical knob. That method allows the shooter to choose a magnification anywhere between 1x and whatever the top end might be. Another method uses a rotating prism and cam system that switches only between 1x and the top end, with no options in between.

I said “No” magnification because even though the image appears to not be magnified, the light is still passing through lenses and being bent. That means that you will still have to deal with the limitations that come with bending light, particularly eye relief, exit pupil, and parallax.

View through a Trijicon TR24G 1-4x scope set on 1x magnification. As long as the head is positioned correctly, this is almost as fast as a red dot sight

Class III optics will have a variety of reticle patterns and illumination methods. Some will have similar BDCs to Class II optics; others will have the MRAD and MOA reticles of Class IV optics. Some will illuminate the entire reticle, others will only illuminate certain segments that best draw the eye in CQB situations. The turrets on Class III optics may or may not be easily adjustable, it really depends on the design of the scope and where it errs more towards speed or precision. These optics usually have a diopter adjustment for eyes, and may or may not have a parallax knob (AKA a focus knob).


Class III optics offer a fantastic range of capabilities. Set at 1x, they are nearly as fast and user-friendly as Class I optics. Set at higher magnifications, they retain much of the same capability as Class II optics. I used to shoot several local 3-Gun matches with my trusty Trijicon TR-24G. Being able to use the big glowing green triangle up close at 1x and then quickly switching to 4x for 200-300 yard shots gave me a huge advantage. To an outside observer, they really offer the best of both worlds. But there are tradeoffs.

Class III optics are heavier than either Class I or Class II optics, usually weighing between 1 and 2 lbs without a mount. They also have increased mechanical complexity, which means there is higher risk of parts breakage. Overcoming the durability issue means increased cost in engineering, manufacturing, and parts. Trijicon’s VCOG, a Class III optic designed to be as tough as their ACOG line, costs around $2500. The ELCAN SpecterDR, which switches between 1x and 4x, is around $2200. If you don’t mind losing the ruggedness aspect of the high end options, other quality Class III optics cost between $600 and $1500.

Class III optics occupy a solid middle ground where they are the jack of all trades, but master of none. They are can be nearly as fast as Class I optics up close, but lose out due to eye relief and parallax. They can be as useful at distance as Class II optics, but are heavier and less durable. If you do not need to operate on the extremes of speed and/or durability, then the Class III is probably a good option for you.

If this is the way you want to go, I highly suggest The New Rifleman’s guide to variable optics.

As for myself, I wouldn’t spend less than $600 in this category. There are a lot of options out there, so do your homework.

Class IV Optics: Mid to High Magnification


This is the same as Zak Smith’s Type III optic for SPRs. I look at this category as optics geared more towards precision than anything else.

For the most part, Class IV optics have all the same traits as Class III optics, with a few notable changes. The low end magnification in this class is greater than 1x, and will usually be 2.5, 3, or 4x. The high end will probably be somewhere between 9x and 16x, or beyond. The reticles will almost always be of MRAD or MOA design, and turrets should be readily adjustable to account for range and windage. These are designed to effectively take the rifle to the limits of its capability.

The higher magnification levels of Class IV optics are useful for observation and target identification, but can severely limit how a rifle is used. More magnification means  more movement in the scope. Things that you might not notice with a Class I optic, or barely notice with a Class II or III, like your heartbeat or muscle tremors become readily apparent and frustrating from unstable positions. For this reason, Class IV optics are mostly limited to supported positions where these instabilities are mitigated.

I only advise Class IV optics for AR platform rifles if the rifle will primarily be used from a bench or other stable platform in a long-range or precision shooting format. For practical marksmanship or field use, most shooters will be better served by an optic from Class I, II, or III.

Class V Optics: Digital Hybrids


In a way, Class V is the world of science fiction. Class V is a new category of computerized rifle optics. I’m not talking about night vision or thermal sights that overlay a reticle, but rather actual computers that provide real time information to the shooter and/or calculate ballistics on the fly.

I attribute the creation of this class to the Tracking Point system introduced a couple years back. The company has struggled mightily since its introduction, but I predicted back then that the technology would get smaller and cheaper over time. This optic integrates laser rangefinding, a ballistic computer, a digital display, and even includes a fire control system to automatically fire the rifle when the correct point of aim has been achieved. I don’t particularly care for the last bit, but it exists. The shooter is not looking through glass with the Tracking Point scope, but a digital picture that is zoomed in like a video camera. Something to remember with this optic is that if the electronics fail, the whole scope is dead, you cant see through it.


Trijicon has teamed with Kopin Corporation to develop a digital heads up display inside of the ACOG. This has more promise, as losing the digital display still leaves the ACOG in play. This is still in the conceptual R&D stage, so there is not much to say. I would expect that the future is in combining this technology with other classes of optics.

A final note on Optic Combinations


Something I left out is the combining of more than one class of optic on the same weapon to overcome the shortfalls of either one individually. The most obvious example of this is putting a QD or flip-to-side magnifier behind a Class I optic. Another example is placing an offset miniature red dot sight (Class I) next to a higher magnification optic (Class II, III, or IV). At the last SHOT Show, Leupold demonstrated their new D-EVO, which uses an offset 6x scope and mirrors to place a magnified sight picture just below a red dot sight, allowing the shooter to choose which one to use by merely looking downward with their shooting eye.

These are all viable solutions. If you are willing to pay the penalty in increased weight, cost, or complexity to go this route, then go for it.


This is a lot of information. If you were simply looking for what optic you should buy, then I’m sorry. My goal is for you to think about your probably uses, and choose a class of optic that best meets your needs. Once you have decided on that class, then there are many web sites out there that can get you closer to which one you should buy. But at least you know you’re going in the right direction.


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