The “co-witness” refers to the alignment and interaction between iron sights and optics sights, such as a red dot sight.
Many wonder, “Why do you need a co-witness if you have a red dot sight?” or “Can’t I just co-witness with the front sight? Why do you say I need a rear sight?” There are reasons for these questions. I prefer having a complete backup for my red dot sight. I appreciate technology and enjoy using red dots, but having a reliable backup is crucial.
— Yankee
Co-witness sights, an integral component of modern firearm optics, refer to the alignment of iron sights with optical sights on the same plane. This alignment allows shooters to utilize both sight systems simultaneously or independently. In essence, co-witnessing ensures that if the primary optic fails or becomes compromised, the iron sights remain a reliable fallback.
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ToggleTypes of Co-Witness
There are two primary types of co-witness sights: absolute and lower 1/3, also referred to as 100% co-witness, and lower third. Each type is ideal for different scenarios. The best option for you will depend on what you find most convenient and comfortable for your shooting style. Both rifle and pistol optics can be co-witnessed.
1. Absolute or 100% Co-Witness: In this setup, the line of sight for both the iron sights and the optic are the same. This has significant advantages: zeroing is easier, and if the optic fails, no shift is necessary—simply refocus on the iron sights to continue.
2. Lower 1/3 Co-Witness: This setup places the iron sights in the lower third of the optic window. The advantage is an improved FOV since the sights are lower in the optic. However, it creates two sight pictures—one from the optics and one from the sights—which can be slightly disorienting, though acceptable if the irons are intended only as a backup.
Pistol Absolute Co-Witness VS Lower 1/3 Co-Witness
If you’ve been following the defensive, concealed carry, or competition handgun market over the past decade, you’ve likely noticed the increasing popularity of slide-mounted mini red dot sights (MRDS), either alongside or replacing standard iron sights. Today, most handgun manufacturers include at least one model with optics-ready options for a red dot sight.
An absolute co-witness places the iron sights in the center of the field of view (FOV), ensuring alignment between the sights and the red dot. These mounts are shorter in height compared to lower 1/3 co-witness mounts, positioning the iron sights at the same optical height as the red dot.
A lower 1/3 co-witness places the iron sights in the lower third of the field of view (FOV), providing a less obstructed viewing window. In this setup, the red dot remains above the sights. These mounts are taller than absolute co-witness mounts, allowing the red dot sight to sit higher above the iron sights.
Rifle Absolute Co-Witness VS Lower 1/3 Co-Witness
Currently, the most popular AR-15 setup features a red dot sight along with backup iron sights. The two most common types of co-witness in an AR are “Absolute Co-Witness” and “Lower 1/3 Co-Witness.”
AR-15 Absolute Co-Witness Sights
In this configuration, the red dot optic and backup iron sights are mounted at the same height. The red dot aligns directly with the sight post, both centered in the optical window. This setup allows for easier adjustments if your optic loses power or you transition from a darker to a lighter area. Quick responses are facilitated as no realignment is necessary.
AR-15 1/3 Co-Witness Sights
Here, the red dot optic is mounted higher than the iron sights. The iron sights appear in the lower 1/3 of the optic when the red dot is centered in the optical window. This provides a less cluttered sight picture, enhancing visibility. This setup is ideal if you need a clear view of your field and target, making target identification easier. Additionally, it offers more comfortable neck positioning and may reduce muscle strain.
Why should you use Co-Witness Sights?
1. Fail-Safe Backup:
Red-dot optics are typically favored for close-quarters weapons, where speed is crucial. Being able to instantly switch the focal plane from one sight picture to another and quickly re-engage is a significant advantage.
2. Ease of Transition:
Co-witness sights help shooters transition from iron sights to optics smoothly.Co-witnessed sights allow shooters to use iron sights as a guide while getting accustomed to the red dot, providing a backup on carry guns until the transition is complete.
3. Versatility for Different Purposes:
Shooters may prefer irons and optics for various tasks. For example, red dot optics are highly effective for longer distances (25 yards or more), while iron sights are favored by many for close-range engagements. Additionally, different lighting conditions may necessitate the use of iron sights or optics. Red dots without ambient light sensors might be too dim in daylight, but co-witnessed iron sights ensure you’re always ready.
Using this mounting method, you’ll gain increased precision and have a backup optic. It’s always advantageous to have a backup in case your primary optic or iron sights become inoperable. Having multiple options is beneficial, whether you’re at the firing range, on a hunting expedition, or in active combat.