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The Best AR-15 Optics in 2021

Kenzie Fitzpatrick


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Disclosure: Products are selected by our editors. We may earn a commission on purchases from a link. How we select gear.

When it comes to AR-15 optics, there isn’t a one-size-fits-all answer. A rifle’s purpose — what you are trying to achieve with your rifle — should inform your choice of optic.

From red dots to prisms, holographic sights, reflex sights, and long-range scopes, we’ll go over what to look for in a quality optic, as well as why you’d pick one type over another when fleshing out the AR platform. 

What to Look for in a Quality AR-15 Optic

1. Durability

AR15Optics- Holosun 510C
The Holosun 510c's hood protects the internals from all the bumps and bangs.

No matter what optic you choose, the number one thing it should do is hold zero. What does that mean? When you first zero a red dot or scope, it means you have set it up to hit bullseye every time at a distance of your choosing. 

If this accuracy changes and your shots start to impact a target one moa dot too far left or two moa dots low to the right, for example, your optic may have lost zero. Several things can cause an optic to lose zero, including a mounting issue, dropping the rifle, lower quality turrets, or even a defect from the factory. 

A quality optic will be durable enough that few things change it’s zero — being dropped doesn’t change it, quick detaching it and reattaching it doesn’t, and using it in harsh weather conditions doesn’t change zero. We aren’t looking for a “safe queen” when it comes to optics — you want something that will lock into a Picatinny rail and hold on for the long haul.

2. Warranty

The manufacturer’s warranty is an essential consideration in a quality AR-15 optic. Suppose the manufacturer stands by its products and offers a lifetime warranty, for example.

In that case, you can trust that if there ever is an issue with your optic, the company will take care of its customers and give you the freedom to use their products as intended.

3. Waterproof & Weatherproof

If you shoot outside, you’ll run into less than perfect weather conditions. 

Most red dots, holographic sights, and even scopes will have a battery insert with some sort of cover or which requires a screwdriver to open. Never purchase an optic that doesn’t offer waterproof housing or cannot be exposed to the elements. Also, a pressurized aluminum housing will prevent condensation and keep the glass clear for as long as you own it.

Whether you’re shooting for fun, competition, or building a rifle for home defense, the optic needs to be just as tough as the gun and useable in any condition. The adage
“buy once, cry once” isn’t just true for firearms.

4. Battery life

Battery life should be a key consideration if you plan to use a red dot on your AR-15. Compare the hours of life a manufacturer advertises their optic will last on a single battery. Some red dots will turn themselves off after a set amount of time and even run off solar energy. 

If you’re forgetful like me and often simply forget to turn the dot off, you should choose a dot with battery-saving functionality, or you’ll be swapping batteries as frequently as mags.

5. Parallax

If you are looking at AR-15 optics specifically for long-range hunting or precision shooting, parallax adjustment features are an essential factor in choosing a quality optic. 

On a scope with an adjustable objective (AO), you should be able to use the AO on the scope to eliminate reticle movement at the highest magnification point. 

A scope with a side focus can be beneficial for setting up deliberate shot adjustments, so you have a precise parallax when shooting longer shots & a faster means of adjusting to unknown yardages.

6. Eye relief/easy to mount

Eye relief and effective scope mounting go hand in hand. A quality optic will have enough eye relief to serve its purpose on a rifle while making it easy to mount. 

Eye relief is the distance from your eye to a clear picture in the scope lens. 

A high-recoil hunting rifle using a long-range scope will typically require 5 to 6 inches of eye relief, so the shooter doesn’t get hit in the face by the scope or the rifle itself when firing a shot. 

Look for an optic that offers a safe amount of eye relief when mounted and is clear enough to see what you’re aiming at through the lens.

7. Field of view

Holosun 510c reticle at 50 yards
You want to be able to see your target clearly -- but also maintain awareness of your your surroundings.

A quality AR-15 optic will have a large and clear field of view. If you use your rifle for hunting, long-range precision shooting, or competition, this should be a deciding factor when picking an optic. 

As you increase magnification on a scope, the field of view becomes smaller. On a quality optic, you will still have a large field of view even as magnification increases. Tunnel vision will impact your ability to range and land shots at significant distances.

If hunting at a distance, you need a clear view of both your target and what’s behind it. If you can’t get a clear picture or see wider than the animal through an optic, that is not high quality enough to use for this purpose. You’re over-extending the optic and will either need to move close to the target or consider higher-magnification glass.

Types of AR-15 Optics

Red Dot Sights

A red dot sight is a non-magnified optic that uses an illuminated red (or green) dot for a shooter to point and aim. These are most commonly used at close to moderate ranges for tactical and close-quarters combat (CQB). When it comes to a first optic, many run a dot as their first foray from irons.

Their lack of magnification and ability to keep both eyes open when using them maximizes field of view and situational awareness, which makes them great for fast target acquisition. Your eyes don’t need to balance the sight radius of your rifle — you just put the dot on the target and pull the trigger. 

They’re not as flexible as longer-range optics (generally no turrets and limited adjustability). Still, they’re incredibly popular for a reason — they work — and for many people, they’re the best choice for an AR-15 optic.

Trijicon MRO

The Trijicon MRO is a miniature, waterproof red dot reflex sight that is very simplistic in design. It has ambidextrous brightness controls and is optional with a co-witness mount. 

Co-witness means your red dot is aligned with your iron sights when you shoot a target, often creating a “lollypop” with the front sight post. Co-witnessing is beneficial because if anything goes wrong with your red dot or the battery dies, you can always use your backup iron sights without adjustment. No power, no problem.

Primary Arms SLX Advanced

Primary Arms SLX Advanced Push Button Micro Red Dot Sight - Gen II
  • Ultra-sharp 2 MOA dot
  • AUTOLIVE Motion activation, 50,000-hour battery life
  • Ambidextrous top-mounted push button controls, Low profile turrets

Primary Arms designed their SLX Advanced Push Button Micro Red Dot to be motion-activated and pack a 50,000-hour battery life. Just like the Trijicon MRO red dot, it can be co-witness mounted with iron sights.

Not only does it have a high-powered emitter for use in bright daylight, but it also is night vision compatible, so if you’re planning on tackling a hog problem or want to stalk around in the dark of night, Primary Arms has you covered.

Aimpoint CompM5

The Aimpoint CompM5 red dot is AR-15 ready and is one of the higher-end red dots on the market. If you’re on the hunt for a budget option, you may want to look elsewhere. Aimpoint crafts its optics for performance and durability under the roughest conditions, and the CompM5 is no different — with a battery that lasts over five years of constant operation. 

This optic features flip-up lens covers with the rear being transparent to allow a shooter to use their dot in an emergency or tactical situation. And who doesn’t love the QD mount on the CompM5? Easy on, easy off.

For a more budget-friendly Aimpoint product, check out the Aimpoint PRO. It has many of the same features (2 MOA dot, night vision compatibility), but the Aimpoint PRO be picked up for less than half the price of the CompM5. You don’t get the 5-year battery life of the CompM5, but most guys will be happy with the 3-year life the Aimpoint PRO provides.

Sig Sauer Romeo5

Sig Sauer Romeo5 1x20mm Compact Red Dot
  • Sig Sauer Romeo5 Compact Red Dot Sight - SOR52010
Sig Romeo5 Mounted
My Sig Romeo5 mounted on my DD M4A1. The one knock I have against the Romeo5 is the use of a star bit for mounting purposes, but it's a minor gripe.

The Sig Sauer Romeo5 is a very popular red dot with unique ultra-low parallax, motion-activated illumination, and get this — 40,000 hours of battery life. Sig Sauer has embraced optics development for years, and they’re well established in the red dot game.

Sig Romeo5 Top Buttons
Top-mounted brightness adjustment buttons & height adjustment under the smaller top cover.

The Romeo5 has proven so popular you see other brands building very similar products (cough, Sparc AR, cough). Not that the Vortex Sparc AR isn’t a great product in its own right when it comes to red dot sights, but my personal preference is the Sig Sauer product.

Sig Romeo5 Co-Witnessed
Bright, daytime use is easy to adjust for with the top-mounted adjustment buttons.

The brightness adjustment buttons are top-mounted and have a nice tactile snap when pressed. The brightness changes of the red dot are easy to see from one to the next, and changing from a low setting in a dark room to bright daytime use is quick and easy.

I can snap to targets quickly with it co-witnessed on a front sight post, thanks to the taller mount on the Romeo5.

Sig Romeo5 Right Side
The right side of the Romeo5 houses the windage adjustment and battery compartment. Both of which have a slot for opening with a coin and knurled sides that allow for tooless opening.

Trijicon SRO

Trijicon SRO Sight Adjustable LED 5.0 MOA Red Dot, Black
  • LARGE, UNOBSTRUCTIVE FIELD OF VIEW: Parallax-free and compatible with suppressor-height iron sights
  • CLEAR, CRISP DOT: Fine-tuned, illuminated reticle, coupled with exceptionally clear front lens,...
  • EASY, ADJUSTABLE WINDAGE & ELEVATION: Tool-less design makes zeroing hassle-free
AR15Optics- Trijicon SRO
The SRO's buttons are easy to use with one hand.

Trijicon designed their SRO sight parallax-free and compatible with suppressor-height iron sights, making this an optimal home defense or tactical red dot. Plus, it pairs well with a tactical light if you’re looking for the ultimate home defense build.

AR15Optics- Trijicon SRO
The SRO gives you a massive field fo view.

The left/right oriented brightness buttoens have a nice tactile feel, and make for easy one-handed operation.

You get a massive field of view with the SRO and the same small footprint as Trijicon’s famous RMR sight, giving you the best of both worlds.

AR15Optics- Trijicon SRO
The tiny little red dot sight fits about anywhere.

Holographic Sights

A holographic sight is a non-magnified optic with a glass window that presents a holographic reticle for shooters to aim through. A holographic sight can provide better magnification than red dot sights and typically have oversized viewing windows.

Plus, they can still operate even if the front lens is damaged, unlike a red dot. They’re best for tactical setups and short to medium-range use, and many 3-gun participants swear by them.

Holosun 510C

AR15Optics- Holosun 510C
My 510C has been through some stuff.

Holosun is well known for its holographic sights, which pack 100,000-hour battery life with solar fail-safe technology. The Holosun 510C has an unlimited field of view with a huge window to see through.

It is waterproof and durable even with high-recoiling rifles. It also has a solar panel for backup battery life and comes with a QD mount for easy mounting on and off rifles.

AR15Optics-Holosun co-witnessed
The blocky 510C viewport is great for co-witnessing irons


EOTECH Holographic Weapon Sight, Ring with Single Red Dot Reticle, black
  • EOTECH XPS2-2: Holographic Weapon Sight in black with 68MOA ring and (2) 1 MOA dot reticle
  • Mount: Compatible with both 1" weaver and MIL-STD 1913 rails
  • Adjustable Brightness: The XPS2 has 20 brightness settings for use in any lighting scenario

EOTech designed the XPS2 green holographic weapon sight to be extremely light and compact with the green reticle rather than the traditional red, making it easier to see in daylight conditions when compared to a red dot.

The green color is often more accessible to the eye, which speeds target acquisition and awareness. For these reasons, 3-gun and competitive shooters will usually run a green dot.

Prism/Fixed Magnification

Prism and fixed magnification optics serve a specific purpose. These optics have an etched reticle that can be viewed without battery power — comforting in self-defense or tactical situations. 

In addition to running and gunning without power, prism scopes are best for shooters with astigmatism. They use both a lens and etched glass to produce the reticle, reducing distortion.

Athlon Optics Midas TSP4

Athlon Optics Midas TSP4 Prism Scope, Black
  • Reticle etched on the glass or prism that provides excellent backing support for complex reticle...
  • Fully Multicoated optics effectively reduces reflected light and increases the transmission of light...
  • Smart Power Management System shuts the unit off when no adjustment is made in 6 hours. The product...

The Athlon Optics Midas TSP4 Prism Scope has a reticle etched on the prism that stays visible even without power.

The reticle shuts the battery off after 6 hours of no adjustment, and it’s waterproof — one of our critical consideration criteria for an AR optic.

Vortex Spitfire

Vortex Optics Spitfire HD Gen II 5X Prism Scope - BDC4 Reticle
  • The Spitfire HD Gen II 5x prism scope offers ultra-fast target acquisition while still being usable...
  • The updated optical design and fully multi-coated lenses provide improved resolution, and cuts...
  • The BDC-4 reticle is built for rapid target and acquisition holdovers out to 650 yards while...

The Vortex Spitfire 3x AR-15 optic is night vision compatible with 12 illumination settings. This fixed prism scope has a 3x magnification level with quick holdovers at known distances.

Variable Magnification

Variable magnification optics (or LPVO “low power variable optics”) allows the shooter to adjust from one magnification power to another. The magnification adjustment is made with a power adjustment ring located on the eyepiece of the scope. These scopes are popular among 3-gun shooters and hunters using their rifles for targets up to 500 yards away.

Vortex Optics Razor

Vortex Optics Razor HD Gen II-E 1-6x24 SFP Riflescope VMR-2 MOA
  • The Razor HD Gen II-E sheds nearly a 1/4 pound from its predecessor, is feature rich, and extremely...
  • The APO optical system delivers stunning image quality through premium, high density, extra-low...
  • A low-profile locking illumination dial has 11 levels of brightness with off positions between each...

The Vortex 1-6 Razor is durable enough for the heaviest heavy recoil rifles and is a waterproof optic. This scope includes illumination for 11 levels of brightness — plus Vortex also backs all of their products with a lifetime warranty, so if the Razor ever fails, you’ll know Vortex will stand behind it.

Trijicon Credo

AR15Optics- Trijocon Credo Mounted
The Credo mounted on a Warne mount

Trijicon recently released the Credo 1-8×24 scope. This platform falls under the first focal plane, variable magnification scope umbrella, but with Mils holds, this scope can be used for hunting and longer-range shooting as well.

It has both red and green illumination settings and includes a segmented reticle for CQB shooting.

AR15Optics- Trijicon Credo Turrets
The Credo's turrets provide a smooth but tactile feel

Kahles K161

One of the other popular brands for variable magnification scopes is Austria’s Kahles. They’ve been in the quality glass game since 1898 and know how to build bullet-proof optics.

The Kahles K16I 1-6×24 scope is a highly durable LPVO scope with a clear field of view and parallax adjustment settings to help you keep your shots on target at significant range.

Hunting Scopes

When it comes to hunting scopes, you should look for more magnification than a low-power variable optic.

This additional magnification doesn’t necessarily mean you’ll use the max magnification around the clock, but the minimum will be a lot clearer and provide a wide field of view — critical for surveying your targets when hunting animals.

Vortex Optics Razor HD

Vortex Optics Razor HD 5-20x50 First Focal Plane Riflescope - EBR-2B Reticle (MRAD), black, One Size
  • The Razor HD 5-20x50 riflescope is built to handle the needs of precision and tactical shooters...
  • High density, extra-low dispersion glass and premium XR coatings generate unparalled image quality...
  • The glass-etched, first focal plane reticle is incredibly versatile and ensures subtensions remain...

For starter hunting optics, the Vortex Optics Razor HD 5-20×50 is an approachable, reliable optic that stays under the $2k mark. This scope features a side focus to help with parallax removal.

Plus it’s waterproof, fog-proof, and coated to protect the lens from oil, dirt, and scratches.

Leopold VX-6HD

The Leopold VX-6HD 3-18 scope is the ultimate hunting scope. Some features include an in-scope electronic reticle level, a removable throw lever, and a zero lock elevation dial.

It also has motion sensor technology that saves the battery by shutting off after 5 minutes of no activity and is reactivated when movement is detected.

Athlon Optics Argos

Athlon Optics Argos BTR GEN2 10-24x56 Riflescope - BLR SFP IR MOA, Black
  • 0. 125 MOA Click Value, 50 MOA Total Adjustment, 15 yards to infinity Parallax adjustment
  • Fully Multicoated optics effectively reduces reflected light and increases the transmission of light...
  • Precision Zero Stop system allows you to lock down your zero position and dial back to it with a...

Athlon Optics Argos BTR GEN2 10-24 scope has 15 yards to infinity parallax adjustment. This scope is waterproof and features a zero stop system to lock your zero and dial back to it easily when needed.

Long Range Scopes

Long-range scopes should have a clear field of view, whether at their lowest or highest magnification. These scopes should have adjustable parallax settings and enable the user to dial-up or down target distance quickly and reliably.

They will also often include on-rage specific features like a bullet-drop compensating reticle (or BDC) and high-quality turrets, but they can also be heavier than other optics so it’s best to contrast the additional weight against your specific needs.

Nightforce ATACR

The ATACR 7-35 rifle scope by NightForce has a vast and clear field of view even at its highest magnification. It also has parallax adjustment down to 10 meters, features the zero stop elevation adjustment, an illuminated reticle, and has a built-in throw lever for ease of use, helping to hit those long-range targets quickly.

Plus, Nightforce’s ATACR MIL-SPEC ATACR 4-20×50 F1 was recently selected for inclusion into the USSOCOM program. Hard to get better recognition than that.

Kahles K525I

Kahles designed the K525I 5-25 scope with long-range competitors in mind. This scope has a parallax spinner, an illuminated reticle, and an extra-long throw lever.

Schmidt & Bender PM II

Schmidt & Bender’s scopes are known for their durability on some of the largest caliber rifles with heavy recoil (think .50 cal). Their PM II/LP 5-25 scope allows for parallax adjustment from 10 meters to infinity.

The glass on this scope is so clear that it can stretch out to over 2,000 yards.

Back-Up Iron Sights (BUIS)

Back up iron sights are a good idea whether they co-witness with your red dot or are run offset. The saying “two is one, one is none” speaks to the idea that if you run an optic without backup irons, you have no failsafe, which is unacceptable in a self-defense or combat scenario. 

Magpul MBUS

Magpul MBUS Flip-Up Backup Sights, Black, Rear Sight
  • Impact resistant polymer construction provides light weight and resists operational abuse
  • Spring-loaded flip up sight easily activated from either side or by pressing the top
  • Detent and spring pressure keeps sight erect but allows for unobstructed folding under impact, etc.

One of the easiest BUIS to install is the Magpul MBUS PRO Steel Sight Set. They mount onto about Picatinny or STANAG rail. The sights are made of steel and include a windage adjustment knob.

Meprolight FRBS

The Meprolight FRBS is a set of flip-up sights with tritium rear dots that illuminate in low-light settings as well as toolless adjustment so you’re always in the fight.

Midwest Industries

All rifles should have a set of offset sights. Midwest Industries created the AR-15 combat rifle offset sight set for easy mounting and with the use of an optic on the top rail.

In closing

As you can see — there are a TON of AR-15 optics available, each with their own nuances and best uses. Brands from every corner of the firearms world ply their trade with AR optics, and these products from Vortex, Sig Sauer, Primary Arms, Trijicon, and Aimpoint are just the tip of the iceberg. 

Decide what the purpose of your rifle will be before looking at AR-15 optics. Once you have a goal for your AR platform rifle, choose a high-quality optic that will last you a lifetime and have you shooting better than ever.

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