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Precision AR-15 Builds: Rifle Scopes for Proper Target Acquisition

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On the topic of long-distance shooting, the AR-15 isn’t usually the rifle platform that comes to mind. Known for its modularity and adaptability in different applications, most standard AR-15s have an effective range of around 500 yards, which isn’t exactly “long range”.  

However, in truth, the AR-15 is more than capable of ringing steel past 750+ yards. We talk about this at length in our SPR guide, but it’s more than possible to build out an AR-15 rifle to be more than capable of making consistent and accurate shots across vast distances. As these types of rifle builds have become increasingly popular, enthusiasts have run into a notable issue, choosing the right optic.  

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Understanding Long Range AR-15 Builds 

Before delving into the intricacies of different optic options, it’s important to understand the platform. The AR-15, as we mentioned above, is one of the most modular and adaptable rifle platforms ever designed. As such, just about every part of one can be swapped out with another that better fits a different task; there are even dedicated lower parts kits with specialty components for precision builds.  

With so many specialized components available for them, AR-15s can easily be built to different specs. Even further, building a rifle gives you full control over what components go into your rifle, allowing you to have your choice of caliber, barrel length, and its lower components.  


When you think of what caliber an AR-15 is, you likely think of its main caliber, 5.56 NATO. Though it offers solid ballistics and lends itself to multiple applications, most standard AR-15s have an effective range of around 500 yards, which isn’t really “long range”. However, by using specific components and cartridge variants, like Mk. 262, this range can be extended to upwards of 750+ yards or more in a well-built rifle. Mk. 262 is the round the original Mk 12 SPR Models were built around. It featured a 77-grain Sierra MatchKing bullet which is still used today by enthusiasts for their precision rifle builds.  

In addition to 5.56 NATO, calibers like 6.5 Grendel and 6mm ARC are commonly used for long range AR builds. Both 6.5 Grendel and 6mm ARC are incredibly versatile rifle rounds and have flatter trajectories and higher ballistic coefficients compared to 5.56 NATO. Plus, they’re capable of accuracy beyond 1,000 yards. These calibers have become commonplace for precision builds and are even featured in precision rifle models from Geissele and Cobalt Kinetics. 

Barrel Length  

On standard upper receivers, common barrel lengths include 14.5, or 16 inches. which is optimal for routine use and competition. For precision rifle builds, it’s more common to see 18- to 22-inch barrels being used.  

Longer barrels are more conducive to long range shooting, allowing the projectile to reach higher velocities and increasing its effective range. It’s worth noting that you can still get solid performance out of a 16-inch barrel. The Mk 12 Mod H was a 5.56 SPR that used a 16-inch barrel instead of the standard 18-inch one. Though shorter, it was still capable of making consistent impacts on targets upwards of 700+ yards away.  

Just like with choosing a caliber, picking a barrel length is a matter of finding one that best aligns with your references. If you’re looking to get the most reach out of your rifle, a longer 20- to 22-inch barrel is a better option. Conversely, if you want a rifle that’s nimbler while still being effective when precision is needed, a 16- or 18-inch barrel is the way to go. At the end of the day, you can always have multiple uppers to pair with one lower receiver.  

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Choosing the Best Scope for Long Range Shooting 

For a dedicated long-range shooting, variable power rifle scopes are the best choice. They’re equipped with multiple magnification levels, are offered with a myriad of reticle systems, and can be effective for both close- and long-range engagements, depending on the optic. Still, there’s a lot to consider when choosing an optic such as its magnification.  

Magnification Ranges 

When shopping for an optic, it’s common for new enthusiasts to start looking for the highest power scope they can find, because the common misconception is that higher power scopes mean greater accuracy. While this isn’t necessarily a wrong mentality to have, you can benefit more from having a more optimized magnification range for your rifle. For instance, if your rifle is built for precision rifle build still needs to be nimble enough for use in close quarters without needing an offset optic, an LPVO with a 1-8x or 1-10x magnification range is more adaptable for that purpose. 

On the other hand, while an LPVO can certainly work well as a precision rifle optic, they won’t always give you the best results in terms of their overall sight picture. Optics with wider magnification ranges will provide you with a better sight picture at long ranges, as they’re able to zoom in on your target much further. As such, they’re often recommended for most precision builds. 

Types of Rifle Scopes 

Like we mentioned before, variable power optics are some of the most popular optics for precision rifle builds. Still, they come in three different flavors, Medium-Power Scopes, High-Power Scopes, and LPVOs (Low Power Variable Optics). Each one is a considerable accuracy upgrade for the AR-15, but they each offer different benefits.  

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LPVOs: For close to medium range adaptability, LPVOs are usually the go-to optic for rifle builds that emphasize agility and precision. They’re most often available in 1-6x and 1-8x magnification ranges, with premium options offering 1-10x magnification. At 1x magnification, these optics offer fast target acquisition and engagement speed. While they aren’t as quick as red dot sights, they’re quick enough to not require the use of an offset dot sight. Magnified, they can range out to around 750 yards, and while it’s possible to shoot beyond this distance, they won’t offer the same sight picture as other optic variants.  

Medium Power Optics: Better for medium to long range engagements, Medium-Power rifle scopes are what most enthusiasts picture when they hear the phrase “rifle scope”. They’re often available in adaptable magnification ranges, with some popular ones for AR-15 builds being 3-18x, 4-16x, and 2-10x. At these ranges, you’ll be accurate at a wide expanse of distances ranging up to and beyond 750 to 1000 yards. While they’re not impossible to use at close range, they’re not the most effective, so most enthusiasts usually opt for an offset red dot sight. Regardless, they make for a great all-purpose optic for precision builds.  

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High-Power Optics: Like medium-power optics, high-power optics, as their name suggests, offer wider magnification ranges. Designed specifically for long-range precision, optics in this class are generally offered in 4.5-27x, 5-25x, and 4-32x magnification ranges, with select premium models offering 6-30x magnification at times. While some may consider this overkill for precision AR-15 builds, they can provide you with a solid sight picture of your target across vast distances. Just keep in mind that high-power optics like these are usually heavier.  

Top Rifle Scope Brands for Long Range AR-15 builds 

As we’ve mentioned throughout this article, there are a lot of optics to choose from, with dozens of high-quality manufacturers producing a myriad of excellent picks. This variety can make it difficult to pick just one optic. Below are some suggestions to help you get started in your search:  

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Primary Arms Optics: Primary Arms Optics offers a diverse line of optics that are tailored for multiple applications, and as such, we have many scopes with ACSS reticles that pair well with precision AR-15 builds. Out of our lineup, our GLx® 4-16×50 FFP (First Focal Plane) Rifle Scope with the ACSS® HUD DMR Reticle is a solid pick.  

Part of our renowned GLx line, this optic offers incredible durability and adaptability while being budget friendly. Additionally, it pairs well with precision AR-15 builds, offering a highly adaptable magnification range and a reticle that’s designed specifically for .223/5.56. Our ACSS® HUD DMR Reticle is calibrated for 5.56 and .308, offering leads for moving targets, auto-ranging elements, and bullet drop compensation out to 1,000 yards.  

If you’re more interested in an LPVO, our PLxC® 1-8×24 FFP Rifle Scope is a great pick. Better suited for close to medium range engagements, this optic comes with our ACSS Raptor M8 Yard 5.56/.308 Reticle. It can range out to 800 yards and can be used for quick target acquisition at close range. If you are shooting a different cartridge or prefer to use your own custom hand loads it is also offered in the Griffen Mil reticle, replacing the BDC with a full mill grid for ranging and calculating drops and drift. For added magnification, our SLx® 1-10×24 FFP Rifle Scope is worth considering. It comes with our ACSS Raptor M10S Reticle, which features many of the same benefits as the ACSS Raptor M8.  

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Vortex Optics: Vortex Optics is one of the most well-known rifle scope manufacturers, with many high-quality optics to their name. For precision 5.56 builds, optic models such as their Viper HD series and Strike Eagle and Razor LPVOs, are some of their most popular offerings.  

Vortex Optics’ Viper series riflescopes are available in multiple magnification settings, with some popular options being their 2-10x, 3-15x, 6.5-20x, and 5-25x optics. Out of the Viper lineup, the Viper HD is the most popular. It’s available with Vortex’s VMR-4 reticle, which can come in both an MOA and MRAD configuration. These optics offer incredible glass clarity and are perfect for long range AR builds.  

The Strike Eagle is one of Vortex’s most popular LPVO models. It’s available in both 1-6x and 1-8x magnification ranges and can come with either their MOA, MIL, or BDC reticle system. Each one offers exceptional ranging abilities that are perfect for precision AR-15 builds. For a greater magnification range, the Vortex Razor Gen III LPVO is available with 1-10x magnification. Being a premium choice, it comes with enhanced glass clarity and is available with either an MOA or MIL reticle choice.  

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Steiner Optics: Steiner Optics is a maker of many durable optics. Their optics are renowned for their rugged designs, being commonly used competitively or for duty use. Optics such as those in their T6Xi line pair exceptionally well with precision AR-15 builds.  

The T6Xi is available in multiple magnification ranges, with some of the popular ones being their 2.5-15×50, 3-18×56, and 1-6×24 options. For medium to long range engagements the 2.5-15×50 and 3-18×56 rifle scopes are your best bet. They’re both equipped with durable scope bodies, Steiner’s Never-Lost™ locking adjustment turrets, as well as a locking diopter ring for ease of use. Both can come equipped with either MIL or MOA reticles that are illuminated for increased visibility.  

Steiner also has an LPVO option in the T6Xi 1-6×24 scope. Being in the same series as the other optics, it shares many of the same features, albeit in a lower magnification range. Currently, it’s only available with their KC-1 MIL reticle. At 1x magnification, this reticle provides you with a clear center dot and a large outer ring for quick target acquisition, with more adjustments and ranging stadia present when further magnified.  

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Nightforce Optics: One of the most well-known optic manufacturers around, Nightforce provides the industry with some incredible rifle scope options. Out of their lineup, the ATACR 4-16×42 and ATACR 1-8×24 are some of the most popular.  

The ATACR series of rifle scopes is one of the flagship optic series’ from Nightforce. Their 4-16×42 rifle scope can come with multiple reticle systems, ranging from MIL and MOA based options to proprietary designs like their MOAR F1. Regardless of which you choose, each option is constructed from lightweight durable aluminum, has premium extra-low dispersion glass, and comes with Nightforce’s DigIllum reticle illumination.  

Being in the same optic family, the ATACR 1-8×24 shares the same quality as Nightforce’s other ATACR scopes. However, aside from its lower magnification range, this optic comes with a daylight visible center dot, a wide field of view at 1x magnification, and it comes standard with Nightforce’s FC-DMx reticle. Weighing only 21 ounces, it’s a great optic choice for lightweight, agile rifle builds.  

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Mounting your Scope on your Rifle 

Once you’ve selected your optic, you’ll need to mount it onto your rifle. Mounting an optic to an AR-15 is incredibly simple, with one of the most common mount types available is a one-piece mount. One-piece mounts have both the front and rear mounts housed in one unit. If preferred, you can opt for two separate picatinny scope rings, but we recommend one-piece mounts for rigidity and simplicity’s sake.  

Most, if not all, modern AR-15 uppers have a picatinny rail section along the top for mounting optics. As such, AR scope mounts usually have picatinny mounts, so adding one to your rifle is as simple as tightening the mounting screws. Mounting an optic to your AR-15 is simple too, but we recommend using added tools such as a bubble levels and an upper bench vise block to ensure your optic is sitting level in your mount. One commonly overlooked tool is a torque wrench. Torquing your hardware down properly is essential for a secure optic that is not damaged. Once it’s secured, you’re ready to head out to the range to get it zeroed. 


AR-15s will continue to be some of the most adaptable rifles available, and with precision builds rising in popularity, finding the right optic is crucial. Having a good optic can significantly enhance your shooting experience, as well as your rifle’s capabilities at long distances.  

Given that optics can be a costly investment, it’s crucial to consider all your options before choosing one. Remember that your optic needs to align with your needs and preferences. So, if you’re still on the fence about which optic is the best choice for you, our long-range rifle scopes buyer’s guide is a suitable place to further your knowledge of what’s available.  

Finally, while a quality scope is essential for long range shooting, it isn’t the only thing you need to maximize it. Our guide on how to accessorize your AR-15 goes over some of the popular accessories you can add to your rifle to have a more cohesive and effective setup.