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Every rifle needs an adequate sighting system. Your ability to see and hit your target depends on it. But if you don’t find factory iron sights satisfactory, an optical sight is the next best thing.
The standard AR-15 iron sights consist of a front post that you place inside a rear aperture sight. Although metallic or iron sights are simple, robust, and, with proper training, are highly efficient, many shooters prefer to use an optical sight. An optical sight is one of the most popular accessories for the AR-15 platform. There are a variety of reasons for this.
If your eyesight isn’t what it used to be, shifting your focus between the front sight, rear sight, and target — all at different distances from each other — can be difficult. If you need to identify a target far away, the lack of magnification can limit your precision. Furthermore, an illuminated reticle remains highly visible against various backgrounds.
Rifle Scope Reticles
When you’re searching for a suitable rifle scope for your AR-15, you’ll have to decide on the type of reticle that you need. There are numerous reticle designs, each serving a different purpose.
Non-Illuminated and Illuminated
Your first choice should be whether to buy a scope with an illuminated or non-illuminated reticle. Non-illuminated reticles are simply black crosshairs that you place over a target. In low-light environments, these can be difficult to discern, especially against dark-colored backgrounds.
Some low-power variable optics, especially those using the Bindon Aiming Concept, feature a brightly illuminated reticle or aiming marker. An illuminated reticle can allow you to acquire a sight picture and track targets rapidly.
The source of illumination may be fiber optics, a lithium battery, the radioactive decay of tritium, or some combination thereof. Fiber optics collect and transmit ambient light, illuminating the reticle during daylight hours.
The radioactive decay of tritium, a hydrogen isotope, releases electrons that produce a green glow when interacting with a phosphor material. Alternatively, the illumination may be provided by a battery-powered LED, the brightness of which is user-adjustable.
Night Vision Devices (NVD)
You can find relatively affordable thermal-imaging and night-vision rifle scopes for your AR-15. These allow you to identify targets at night by amplifying ambient light or detecting infrared radiation.
The original crosshair, or rifle scope reticle, consists of two black intersecting lines — one vertical and one horizontal. You place the center of the reticle, where the two lines converge, on the target. Standard crosshairs may also include a thickened center, center dot, or other marker for additional reference or visibility.
A duplex reticle comprises four black lines that taper toward the center. The outside lines of the crosshairs are thicker, allowing your eye to naturally determine where to place the center. The center lines are fine and don’t obscure the target for more precise aiming, especially as the distance to the target increases.
A BDC, or bullet drop compensator, reticle allows you to predict the trajectory of the bullet by providing holdover reference points. Some BDC reticles also have a rangefinder grid to help you estimate distance based on known information regarding the target or environment.
The dot reticle consists of a red, green, or amber dot or enclosed circle in the center of the sighting system. This dot may be alone or surrounded by additional markers. Many of them are illuminated and translucent.
The German #1 is a classic and simple sight reticle, consisting of two horizontal lines and a single vertical line extending from the bottom toward the center (6 o’clock). In some variants, there is no 12-o’clock crosshair and a noticeable space surrounding the target area. You place the tip of the vertical line on the target to achieve a sight picture.
This reticle is often associated with WWII German sniper rifle scopes; however, they are equally helpful to civilian target shooters and hunters.
In the #4 variant, thin crosshair lines extend horizontally and vertically for more precise aiming.
Mil Dot Reticle
Mil-dot reticles use a series of dots along the crosshairs for estimating the range of a target at an unknown distance. A radian is a unit of angular measurement, and a milliradian is equivalent to 1/1000th of a radian.
The space between each dot on the crosshair equals one milliradian. You can use these one-mil spaces to calculate the distance of a target of a known size, according to a formula. At 100 yards, one milliradian translates to 3.6” (10 centimeters at 100 meters).
Christmas Tree Reticle
The Christmas Tree, as it’s sometimes called, is an extreme long-range (ELR) reticle designed to provide multiple windage and range holdover reference marks. As these display as a tapered grid, they resemble the festive plant.
Rifle Scope Considerations
When searching for a suitable rifle scope, you have to ask a few questions regarding the reticle. Will it interfere with my ability to see the target at the ranges at which I expect to use it? Alternatively, will I lose my crosshair?
That’s why subtension is important to consider. Subtension refers to the thickness or weight of the crosshair lines. Thick crosshair lines that taper toward the center draw your eye toward the aiming point. Fine crosshairs with no thick outer lines can be challenging to acquire under certain lighting conditions or when shooting in an environment with poor contrast.
You need to find the best balance between your sight reticle remaining visible without obscuring the target or the target’s vitals.
Do you prefer your reticle to be at the first or second focal plane? If you prefer your reticle to change size as you magnify the target image, choose the first focal plane. The second focal plane will have the reticle remain fixed in size, regardless of the magnification setting.
When choosing a rifle scope or other type of optical sight for your AR-15, the reticle design can play an important role in your shooting experience. It can affect how easily you see both the reticle and the target at various distances and can provide useful elevation and windage reference points.