How to Co-Witness Your Sights

By Frank Melloni

The absolute co-witness allows for iron sight backup in the event of electronic failure and is easy to set up. (Photo: Frank Melloni)
Regardless of what optics you attach to your rifle, it’s always handy to have a back-up in the event of an electronic failure of the red dot – be it a malfunction or the battery dies. Having iron sights will permit co-witness and engagement of targets even if the red dot dies. Let’s take a closer look at co-witnessing and how it works.
What is co-witnessing: 1/3 and absolute
Co-witnessing refers to a method of mounting iron sights in a manner that allow for them to align with the red dot’s point of aim. This is achieved through the optics lens in one of two ways — lower 1/3 co-witness or absolute co-witness.
Absolute co-witness means that your red dot will sit on the top of your front sight post when aligning your irons and looking through your red dot lens. Lower 1/3 co-witness will require a riser for your red dot and therefore means that the red dot in your lens sits above the front post of your iron sights and your iron sights will appears in the lower 1/3

Source: Guns.com