Everything you need to know before choosing an optic for your AR

When it comes to building your perfect AR15, choosing the right optic is just as important as choosing the right barrel, trigger, BCG. With so many different optics on the market, choosing the right one for your rifle can be a daunting task. Understanding that a firearm is just a tool, and being able to customize your tool for the job is just as important. In this article, we’ll take a more detailed look at some key factors to consider when choosing the right optic for your AR15, as well as the right optic mount.

Consider the Purpose of Your AR15

The first step in choosing the right optic for your AR15 is to consider the purpose of your rifle. This is one of the first questions we ask a customer when they come to our office and are looking to purchase a rifle. Are you building a rifle for long-range shooting? Are you building a rifle for hunting or home defense? Are you looking into thermal optics or night vision? The purpose of your rifle will help guide your decision when it comes to choosing the right optic.

For example, if you’re building a rifle for long-range shooting, you’ll likely want an optic with higher magnification, such as a 4-16x or 6-24x scope. On the other hand, if you’re building a rifle for hunting or home defense, you may want an optic with lower magnification, such as a 1-4x or 1-6x scope. If you’re considering a dual purpose optic you may also look at a 1-10x.

Another consideration is budget, after a quick online search or visit to your local gun shop you’ll find optics ranging in a few hundred dollars to a few thousand. Understanding the price difference and quality of products will help you buy the right product for you.

Choose the Right Magnification

The magnification of your optic is another important factor to consider. Magnification refers to how much an object appears to be magnified when viewed through the optic. Optics with higher magnification can help you see targets at longer distances, but may make it more difficult to acquire targets quickly at closer ranges. Conversely, optics with lower magnification may be easier to use at closer ranges, but may not be effective at longer distances. Another aspect of choosing the right magnification is understanding Focal Planes.

The terms “first focal plane” (FFP) and “second focal plane” (SFP) refer to the location of the reticle within a rifle scope.

In an FFP scope, the reticle is placed in front of the magnifying lens, so that it appears to change size along with the target as the magnification is increased or decreased. This means that the reticle remains proportional to the target regardless of the magnification level. FFP scopes are useful for long-range shooting where precise holdovers and ranging are necessary. The reticle markings can be used to estimate distance to a target and holdovers can be applied at any magnification level.

In an SFP scope, the reticle is placed behind the magnifying lens, which means that the size of the reticle remains constant regardless of the magnification level. This can be useful for hunting or shooting at closer ranges where quick target acquisition is important. However, the reticle markings will only be accurate at one specific magnification level, typically the highest magnification setting. For example, if a shooter wants to use holdovers to compensate for bullet drop at a certain distance, they would need to adjust the magnification to the correct level that corresponds to the reticle markings.

One advantage of an SFP scope is that the reticle will appear finer and less cluttered at lower magnification levels, which can be useful for shooting at shorter distances or in low-light conditions. Additionally, SFP scopes are generally less expensive than FFP scopes.

In summary, FFP and SFP refer to the location of the reticle within a rifle scope. FFP scopes have the reticle placed in front of the magnifying lens, while SFP scopes have the reticle placed behind the magnifying lens. FFP scopes allow for accurate holdovers and ranging at any magnification level, while SFP scopes are useful for quick target acquisition and have a less cluttered reticle appearance at lower magnifications.

Consider the Reticle Type

The reticle of your optic is the crosshairs or other markings that you use to aim at your target. There are a variety of reticle types available, including crosshairs, red dots, and illuminated reticles. Consider which reticle type will work best for your intended purpose and shooting style. In the majority of optics on the market you will find two main measurement styles, MOA and MIL.

MOA (Minute of Angle) and Mil (Milliradian) are both units of angular measurement commonly used in the shooting and optics industry. They are used to measure the size of a target or the adjustment needed to hit a target at a specific distance.

MOA is based on the concept of dividing a circle into 360 equal parts, with each part being a degree. Each degree is then divided into 60 equal parts, or minutes of angle. This means that one MOA at 100 yards is equal to 1.047 inches, and at 200 yards it’s equal to 2.094 inches, and so on. MOA is commonly used in scopes for precision long-range shooting, and adjustments are made in 1/4 MOA or 1/8 MOA increments.

Mil, on the other hand, is based on the metric system, and is defined as 1/1000 of a radian. A radian is a unit of angle where the arc length of a circle is equal to the radius of the circle. One Mil at 1000 yards is equal to 3.6 inches, and at 100 yards it’s equal to 0.36 inches. Mil dots are commonly found in reticles of tactical scopes and are used to estimate the range to a target.

While both MOA and Mil are used for similar purposes, there are some differences between the two. MOA is more commonly used in the United States, while Mil is more commonly used internationally. MOA adjustments are more fine-tuned, while Mil adjustments are coarser. This means that it can be easier to make small adjustments with MOA, while Mil may be more useful for making quick adjustments at varying distances. Additionally, Mil dots can be used for range estimation, while MOA does not have this capability built-in.

Armasight Contractor Reticle Sheet

Thermal vs. Night Vision Optics

When it comes to hunting, especially in low-light or nighttime conditions, having the right optic can make all the difference. Two popular options for hunting in the dark are thermal optics and night vision.

My personal favorite are Thermal optics, Thermal optics use infrared technology to detect heat signatures, allowing you to see in complete darkness or through camouflage. These optics work by detecting the temperature differences between objects and their surroundings, creating a heat map image. This can be incredibly useful for tracking game in the dark or in dense foliage where it might be difficult to spot with the naked eye. Some thermal optics also have the ability to record or live stream footage, making it a useful tool for documenting hunts or sharing experiences with other hunters.

Night vision, on the other hand, amplifies the available light, allowing you to see in low-light conditions. It works by gathering the small amount of ambient light that’s available and amplifying it through an image intensifier tube. This creates a green-hued image that allows you to see in the dark. While not as effective as thermal optics in completely dark environments, night vision can be incredibly useful for hunting in low-light conditions such as dawn, dusk, or overcast days.

When it comes to choosing the right thermal or night vision optic, there are a few things to consider. The first is the quality of the optic itself. Look for a reputable manufacturer that offers a high-quality image and reliable performance. You’ll also want to consider the size and weight of the optic, as well as the battery life and durability.

It is important to note that the entry into both Thermal optics and Night vision optics is significantly more steep in comparison to traditional optics. Often costing 2x-3x the price of normal optics.

Another important factor to consider is the type of game you’ll be hunting. Some animals, such as feral hogs, are more active at night, making thermal optics a great choice for tracking them. Other animals, such as deer, may be more active during low-light conditions, making night vision a better choice.

In terms of mounting these optics to your AR15, there are a variety of options available depending on the specific optic and firearm. Some thermal optics and night vision devices can be mounted directly to a rail system or a Picatinny rail. However, some may require additional adapters or mounting systems.

when it comes to hunting in low-light or nighttime conditions, thermal optics and night vision can be incredibly useful tools for any hunter. By considering the quality of the optic, the type of game being hunted, and the mounting options available, you can choose the right optic to suit your needs and enhance your hunting experience.

Choose the Right Optic Mount

Once you’ve chosen the right optic for your AR15, it’s important to choose the right optic mount to ensure that your optic stays secure and properly aligned. There are a variety of optic mount options available, including one-piece mounts, two-piece mounts, and quick-detach mounts.

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The height of an optic mount is an important consideration when mounting a scope on a rifle, as it affects the height of the scope above the bore of the rifle. The proper height mount will allow for proper cheek weld and sight alignment, which are essential for accurate shooting.

The decision to use a mount with a certain height is often based on the shooter’s preferences and the specific configuration of their rifle. For example, a shooter who prefers a more upright shooting position or who has a longer neck may prefer a higher mount, while a shooter who prefers a more aggressive, crouched shooting position or who has a shorter neck may prefer a lower mount.

Additionally, different types of shooting or different types of rifles may require different height mounts. For example, a shooter who uses a large objective lens on their scope may need a higher mount to avoid interference with the rifle’s barrel. Similarly, a shooter who uses an AR-style rifle with a flat top receiver may need a taller mount to achieve proper alignment with the rifle’s iron sights.

It’s also important to choose a mount that is compatible with the size of your optic. Some mounts are designed for larger optics, while others are designed for smaller optics. Be sure to choose a mount that is the right size for your optic to ensure a secure fit.


Choosing the right optic for your AR15 is an important decision that will impact your shooting experience. By considering the factors we’ve discussed, such as the purpose of your rifle, the magnification of the optic, the type of reticle, and the right optic mount, you can make an informed decision and choose an optic that meets your needs and shooting style. Remember to also take the time to properly zero and calibrate your optic to ensure accurate and consistent performance. With the right optic and optic mount, your AR15 will be ready for anything you throw at it.

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