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How to Choose an Optic for AR-Platform Rifles

Picking the right optic for your AR can be tricky. Here's a walk-through guide to find what's best for your application.

How to Choose an Optic for AR-Platform Rifles
Photo by Yamil Sued

In recent years. Regardless of the rifle’s configuration or intended purpose (defense, competition, hunting or leisure), there’s an option to fit any consumer’s need.

Deciding on what to buy is often aided by the best option being found in product lines aptly designated “AR,” “Tactical,” or similar attention-­getting tag. But don’t limit yourself by blindly adhering to suggestions of clever marketers, who are frequently targeting products to the neophyte. What you need is to find an optic that not only complements your AR’s specific design but also satisfies your requirements regarding zoom ratio, magnification range, dimensions, cost, etc.

So, let’s take a look at the advantages and drawbacks of today’s most popular AR optics: the variable-­power riflescope, the dot-­style (reflex) sight, and the categorically unique options, such as the prism sight/scope and the Trijicon Advanced Combat Optical Gunsight (ACOG). Additionally, we’ll provide suggestions for premium and moderate-­cost standout models for popular shooting disciplines. Ultimately, what is deemed the best for you, your budget and your AR is up to you.

Variable-­Power Riflescopes

The omnipresent variable-­power riflescope is a staple on most modern bolt-­action rifles, and it’s equally well suited for the AR platform, too, especially if precision bullet placement at distance trumps volume of fire. Such optics are available with seemingly incalculable combinations of zoom ratios, magnification ranges, lens coatings, glass, reticles, measurements and more.

Concerning zoom ratios, 3:1 is standard for most economical and midpriced models, though ratios up to 9:1 (or more) are available on upper-­echelon units. The benefit of a higher zoom ratio is that it permits a larger magnification range, and that lends flexibility to an optic. For certain uses, such as 3-­Gun shooting, home defense and some types of hunting, that’s an undeniable advantage.

The ubiquitous 3-­9X riflescope, for instance, is considered to be an “all-­around” choice for big-­game hunting and perforating paper at known distances out to moderate ranges. It’s that effective. So, too, is the 4-­12X. But, with their 3:1 ratio, the low-­end magnification setting is too potent for close targets. Conversely, if a model with excellent low-­end qualities is selected, the top magnification suffers. Stepping up to 5:1, 6:1 or 8:1 improves versatility.

AR Optics
Bushnell Elite Tactical SMRS II Pro 1-6.5x24mm

Some of the scopes I like with good ratios include the popular Leupold & Stevens’ 5:1 zoom-­ratio models including (but not limited to) the VX-­5HD 1-­5X, 2-­10X and 3-­15X, while a 6:1 ratio is found in their VX-­6HD 1-­6X, 2-­12X, 3-­18X and 4-­24X. In 8:1 ratio, the company offers the Mark 8 1.1-­8X and 3.5-­25X. Similarly, Bushnell, in their Elite Tactical series, has the 1-­6.5X, 3.5-­21X and 1-­8.5X, while the AR Optics line has 1-­4X and 4.5-­18X among others. Vortex has an immense selection of optics with some of the standouts being the 1-­6x24mm Razor HD Gen II-­E, Razor HD GEN II 4.5-­27x56mm, Razor HD GEN II 3-­18x50mm and the Viper PST GEN II 1-­6x24mm. You get the point.

Even with these ratios, there are no free lunches, and the tradeoff for high zoom ratios is larger, heavier and more expensive main tubes and the rings used to mount the scopes. Leupold, for example, uses 34mm and 35mm main tubes on its Mark 8 series scopes. Not only do they increase the amount of adjustment travel, but they also enhance brightness and clarity.

When selecting a zoom ratio (and magnification range), be realistic. Although riflescopes with high-­magnification settings and large, bulbous objective lenses are alluring to the eye, they’re impractical (if not detrimental) for close shots. First consider the intended use of the AR, and then choose the magnification range ideal for it. Better yet, go to a sporting goods store and examine several of them side-­by-­side before choosing.

As for the scope’s objective lens, don’t go too big. Unlike many bolt-­action rifles, which have elevated combs or adjustable cheek pieces to aid eye-­to-­scope alignment, most ARs don’t, so you’ll have a difficult time achieving consistent cheekweld. That is mandatory for achieving top accuracy.

An additional consideration when selecting a riflescope is the reticle in the first focal plane (FFP) or second focal plane (SFP). By far the most prevalent models, SFP scopes have a reticle that maintains its size while the image increases and decreases with changes in magnification. When the subtension is changing, the scope’s ranging or trajectory-­compensation systems are only accurate at a specific magnification setting.

Although costlier, a FFP scope’s reticle changes in size with adjustments in magnification, so subtension remains constant; therefore, holdover and ranging systems can be employed throughout the scope’s full magnification range. FFP scopes are well suited for dynamic types of shooting, such as 3-­Gun, the Precision Rifle Series (PRS) and long-­range hunting. These are perfect for anytime unknown ranges must be determined quickly.


Like magnification ranges, select a reticle that’s practical for the known application (i.e., don’t choose a complicated, tactical-­style reticle for close-­quarters hunting or a heavy duplex for distance work). Know that if you choose a basic trajectory-­compensating reticle, it will usually be limited to the caliber/bullet that it will ideally work for, and it takes patience and time well spent to fully learn the more precise systems.

The same applies to turret adjustments whether MOA, mils, centimeters and inches, and if the scope has return-­to-­zero features. The latter being most useful for those continually dialing in DOPE for long shots.

A feature that is most beneficial to competitive and defensive shooters, as well as hunters, is an illuminated reticle. In riflescopes with low-­end magnification settings, the illuminated reticle provides the rapid sight acquisition of a red dot with the benefit of magnification when needed. This is well illustrated in the new Bushnell Elite Tactical SMRS II PRO 1-­6.5x24mm.

Whatever scope design you ultimately choose, ensure that it has fully multicoated lenses, is waterproof, fogproof and shockproof. It should also carry a warranty as a guarantee of quality. I cannot stress this enough: don’t skimp, or you’ll pay for it later, again. The same can be said of the mounting hardware.

Buying top-­tier optics ensures repeatability of clicks (especially important for long-­range targeting), clarity, brightness, reliability and durability. Among the companies offering standout variable-­power optics for ARs (and bolt guns), they include Nightforce Optics, Leupold, Kahles, Swarovski, Zeiss, Schmidt & Bender, Bushnell, Vortex and Burris.

Dot-­Style (Reflex) Sights

Whereas variable-­power riflescopes give the user an undeniable edge for shooting at distance, the same can be said of dot-­style (reflex) sights for close-­quarters work. Generally featuring a radiant dot for aiming, the eye instinctively finds it for rapid target acquisition. They are a boon for self-­defense within an abode or close-­ to mid-­range targets at the range, for competition or afield hunting.

Unlike traditional riflescopes, eye relief is not critical on nonmagnified dot sights, and they can be fired with both eyes open, preserving your peripheral acuity. The aforementioned traits also increase engagement speeds. Ensure that the sight you’re considering is parallax-­free, though. Otherwise, inconsistent sighting will result in poor accuracy. Personally, I favor closed, over-­exposed, red-­dot sights.

Most quality units are lightweight, even when you factor in the mount, battery and lens covers. For example, the Aimpoint H-­1 only weighs 4.1 ounces and is dimensionally unobtrusive, increasing portability and maneuverability.

Because dot sights are subject to being utilized in varying lighting conditions, units are generally equipped with a rheostat featuring multiple intensity settings. The aforementioned Aimpoint has 12 settings, while the Leupold LCO has 16. Crimson Trace’s CTS-­1000 has 10 settings. You get the picture. One must be cognizant of ambient lighting, as it’s easy for the aiming point to be too bright in low light or have insufficient illumination in high-­intensity lighting.

Perfect Red-Dot for ARs: Check the price and purchase the Crimson Trace CTS-1000 sight

When selecting a dot-­style sight, ensure that it has long battery life; unlike the other optics mentioned in this article, when the battery dies on a dot-­style sight, there’s no way to aim your AR — unless you have backup iron sights. Companies have decreased the draw on batteries to the point that it’s practically a nonissue. Aimpoint’s ACET technology enables a single CR2032 battery to power the H-­1 for 50,000 hours (that’s more than five years) of continual use. The Bushnell AR Optics Enrage Red Dot is reported to have the same run time.

AR Optics
Aimpoint ACRO

As for the reticle (or aiming point), I prefer those that are 2 MOA in size. Even at distances approaching 200 yards, it’s surprisingly easy to make quick, aimed shots. This is important for me because I primarily employ them for big-­game hunting rather than defense or competition. For general targeting out to 100 yards or so, a larger 4-­MOA dot might be preferable. It’s best to see them side-­by-­side when making your selection.

It bears repeating that you shouldn’t penny-­pinch when buying a dot-­style (reflex) sight. Among the most frustrated range users I encounter are individuals who purchased a poorly designed and manufactured (at times, outright counterfeit) reflex sight. Common problems include short battery life, inaccurate adjustments (clicks), no shockproofing or being parallax-­free — all are equally frustrating.

Go with a reputable manufacturer and read reviews of the product from numerous sources before committing to a purchase. They should also warranty their products or have stellar field-­proven track records. Top names in the category include Aimpoint, Leupold, Meprolight and Trijicon. Other companies to consider are Vortex, Bushnell, SIG Sauer and Crimson Trace. Like riflescopes, dot-­style (reflex) sights should be waterproof, shockproof and fogproof.

Unique Options

The prism scope/sight offers the precise aiming of a riflescope at distance with the rapid acquisition of a red dot and has an etched reticle that can be illuminated. Incidentally, if the battery dies, the optic is still usable via the etched reticle. That’s an undeniable advantage when used for defense and competition.

The units are usually measurably insignificant, too, so they only add a trivial amount of weight and bulk to your AR. Among the most diminutive models available, Bushnell’s new 1x11mm Lil Prism sight weighs only 4.4 ounces. Yet optics of this type can have greater magnification than dot-­style sights, though eye relief is much more critical. Still, they can be fired with both eyes open. Some of the other companies offering prism scopes/sights include Vortex, SIG Sauer, Burris and Steiner.

AR Optics
Trijicon ACOG

Like prism sights, Trijicon’s fixed-­power ACOGs share many of the advantages of red dots and then some. The tritium/fiber-­optic illuminated reticle is self-­adjusting in brightness and requires no batteries — the optic is always ready to go. The battlefield-­proven optics have a range of reticle types and sizes, as well as magnifications ranging from 1.5 to 6X. Meprolight’s Mepro M21 has similar features to the ACOG.

Because ARs are modular and subject to myriad modifications based upon personal preference, as well as employed for different targets in widely varying scenarios, there’s no one-­size-­fits-­all optic for them. Although not all optics on the marketplace suitable for use on ARs was covered in this article — that would take a whole magazine — I did cover a wide swath. Hopefully, this information will help you to make an informed decision about what primary optic should top your AR.

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