Co-Witnessing to Absolute Co-Witnessing: What Does It Mean?

Co-Witnessing to Absolute Co-Witnessing, sounds confusing, but really it isn’t. Sights are like a stopped analog watch except where a stopped analog watch (the one with hands) is right twice a day, a gunsight is actually right only once. Sights are perfect for the one distance the shooter has sighted the weapon in for. Making an accurate shot at any other distance requires — even with zero wind — either a mental calculation or an adjustment on the sight based on the known ballistics of the round. Bullets generally arc up when fired, so at a target closer than the zeroed point of aim, it will impact high. If shooting at a distance greater than the zeroed point of aim, it will impact lower. Now, the variables of how much deviation depend on the caliber, type of bullet and distance, but the “bullet drop” at distance can be measured in inches, feet, or yards. Generally, only long-distance shooters see the biggest difference, and that is why they have DOPE on where the sights need to be adjusted with the elevation knob to move the point of aim to match the distant point of impact.

At What Distance Does It Matter?

For carbines out to less than 600 yard and pistols out to fifty feet, the difference between point of zeroed aim and point of impact will be sufficiently close (except in competition) for center of mass impacts. But sights are important and now days a whole lot of folks have multiple sighting systems on their weapons. I have seen riflemen with a zeroed optic, a second zeroed optic either offset or on top of the primary optic for close-range threats and a set of back-up, flip-up iron sights. Red dot sights on pistols are now not only common but preferred, but almost all still have open sights as well. So, what, why and how does a shooter use these sights effectively?

Making all the sights perform to put a bullet where you want it involves co-witnessing the sights so that they compliment or match each other. My Glock 45 has an excellent optic that perfectly places its red dot right at the top of my front sight making it an exact co-witnessed pair, but on a carbine of mine, I have a lensed optic for longer ranges topped with a red dot for close-in engagements. On another carbine I have a primary red dot optic with a set of flip-up iron sights that fill the lower third of the red dot optic making it a lower one third co-witness.


What is a lower 1/3 co-witness and is it the best and why?

Best is what works for you. For some looking through an optic and having a blurry iron sight in your line of sight is an unacceptable distraction. Those shooters would tend to want the red dot sight slightly higher than the iron sights, so the iron sights are much less obvious when looking through the optic. The lower 1/3 co-witness height is called that because the iron or back up sights are only visible in the lower 1/3 of the optic. That is achieved either by using a slightly elevated mount for the red dot sight to have the lit reticle slightly above the top of the front sight. Generally, on an AR co-witnessed sights use a sight base .83 inch tall while lower one third co-witness height uses a one-inch-high riser. This provides the shooter a larger field of view, and (some say) quicker acquisition of the sighting reticle. The biggest advantage is that the lower one third co-witness eliminates the distracting, blurred sight post ghosted on the optic when co-witnessed exactly with the red dot. The biggest drawback is having to shift head position to view two different sight pictures resulting in a better chance for shooter-induced inaccuracy and inconsistent shots.

What’s An absolute Co-witness Sight?

Absolute co-witness is when the sighting systems on a firearm are matched so that the point of aim at the top of the front sight post is also the location of the red dot or optic reticle so that the rounds aimed by either land at the same spot. How does that help a shooter? Depending on the lighting conditions, at least one will provide an accurate target solution. It also means that practicing one presentation or hold to obtain a sight picture will work for both making training both consistent and more effective. Absolute co-witnessing also means that with a failure or loss of one set of sights (like a dead battery) will not render the shooter without any ability to properly aim the weapon. It also is good for long guns with a low cheek weld like shotguns and some rifles, that a shooter does not need to alter to use either one. The downside for absolute co-witness is that the iron sights are fully visible through the optic, so one of the best iron or open sights for absolute co-witness is pop-up sights Which co-witness sights are best for a shooter? First do you want them as a back up or to provide immediate targeting if a threat presents itself at a different (usually closer) distance. For a pistol, absolute co-witnessing works well, but pistols right out of the box have sights too short for exact absolute co-witnessing but require tall iron sights like those offered by Meprolight® with their suppressor sights. The taller sights on your pistol with a red dot sight like the Mepro microRDS will provide a pistol shooter with both red dot and open sight options for a common POA/POI. For carbines and rifles a set of pop-up sights absolute co-witnessing with a Mepro M21 red dot optic is superb as well as with carbines and rifles with already mounted fixed sights.

Co-Witnessing To Absolute Co-Witnessing; how do you co-witness your sights? First, do you want them both to match point of aim (POA) and point of impact (POI) or do you want one for near and one for far? For a dual POA and POI using an optic (red dot) and open sights, if one is already zeroed to the distance, you want both, using a LASER bore sighter (you can do this at home) match the sight to the already correct sight. Then go to the range and adjust on one or the other until your bullets match where they strike the target. Ideally the red dot reticle, top of iron sights and impact are all at the same spot for an absolute co-witness. For either lower one third mounts or sights for dissimilar zeros, each sight needs to be independently zeroed and verified.

What Is The Value Of Co-Witnessing to Absolute Co-Witnessing?

A point few make is if a shooter has both, but trains completely or mostly on just the primary sight is poor training. If you have multiple co-witnessed sights, train equally on all of them. During a training class shoot with one and then swap to the other. You don’t want to be the shooter suddenly stripped of using your experience and almost all of your training just because you unexpectedly had to revert to a set of sights last used when you sighted them in!


Co-Witnessing To Absolute Co-Witnessing Are The Marks Of A Pro

Overall co-witnessed sights are the mark of a serious shooter and pros who know the value of every shot and take every variable possible out of the targeting solutions, especially in a crisis situation. Obtaining excellent sighting systems from Meprolight® either using the Mepro Hyper-Bright™ or Mepro Tru-Dot® open sights with a red dot on your pistol or using the Mepro Tru-Vision™ on your carbine with a set of pop-up sights makes sure you know exactly every round down the barrel is fired true and accurate to match the desired point of aim to point of impact. Check out to find the aiming solution that best fits your shooting style.