Co-Witnessing?

10 Mar 08

Co-Witnessing?

When a rifle's optical sight (usually 1X, or minimal magnification)and iron-sights simultaneously share the same sight line, the two a said to be " co-witnessed." In an age of rails, precisely aligning two (or more) sighting systems on the same plane has become a simple task. I'm not sure "co-witnessing" is the most descriptive of terms, but at this point it appears we are stuck with it. Presumably, when two sighting systems use separate sight lines (one directly on top, and the other cast off at a forty-five-degree angle), they are "split-witnessed."

Co-witnessing is a good thing!

(1) Operators can use virtually the same mount and cheek weld with either sighting system. Accordingly, effective use of both is readily available from nearly identical postures.

(1,a) Deliberately mounting an optic well above, or just above, iron-sights usually renders an unsatisfactory result. When an optic is mounted too low, its bottom edge will block the line of sight between front and rear iron-sights, and iron-sights are thus rendered useless until the optic can be removed. Mounting optics far enough above iron-sights to permit their utilization usually places the optic too high for effective employment. And, even then, iron-sights are only marginally useful, as the scope body still blocks out much of the downrange area.

(2) It facilitates, indeed encourages, continuous confirmation and re-confirmation that both sighting systems are adjusted correctly. Iron-sights can be easily compared with the aiming reticle of the optic, and visa-versa. Any time an Operator suspects a sight misadjustment, with either his optic or his iron-sights, one can be quickly compared with the other as the weapon is mounted normally. When both are aligned, he can be assured both are still adjusted correctly. When they are not aligned, one has obviously changed since the last confirmation. This confirmation technique is particularly useful when the rife or optic have been subjected to a blow, or the optic, or iron-sights, have been removed and subsequently reinstalled.

(2, a) Iron-sights, correctly sighted-in and verified through live-fire, can subsequently be used to adjust an optic that is mounted, and co-witnessed, on the same rail, and visa-versa. It is my preference to sight-in the optic first, then adjust iron-sights accordingly, but the process works just as well in reverse. Ultimately, of course, all sight adjustments need to be confirmed through live fire.

(3) It permits the Operator to default to iron-sights when the optic's reticle is no longer visible, because of a battery, electronic, lighting, or contrast issue. Such a default can take place instantly when iron-sights are deployed continuously. The default process will require a second or two when iron-sights are normally folded down. A useful compromise is leaving the front iron-sight continuously deployed, and the rear one normally folded down.

(3, a) Unless the optic is frosted over or otherwise obscured, there is no need to remove it, even when it is non-functional, as co-witnessed iron-sights are altogether useable, through the optic. In fact, a crude, but effective, aiming technique can be accomplished via the front iron-sight and an Aimpoint with no reticle visible. The Aimpoint body itself can function as a large " ghost-ring," rear sight. The further forward the optic is mounted, the more positive this sighting technique becomes.

Mark LaRue makes a wonderful quick-release mount for both Aimpoints and EOTechs. In addition, he makes mating risers, in various heights, that are designed to facilitate co-witnessing with nearly any railed rifle. In my opinion, there is no point in having a 1X optic on a rifle and not co-witnessing it with iron-sights, be they permanent or fold-down.

Marks's system is what I use in order to successfully execute co-witnessing on all my serious rifles. Highly recommended!

/John