Think Twice About Co-Witnessing Your Rifle Sights
BY Herschel Smith
1 year, 10 months ago
I like being confronted by things I’ve never thought about before – or in other words, I like to learn. This is one of those many things.
My take: No glass is perfect, especially the less expensive glass used for fixed magnification sights (1X) and red dot optics. There will be some parallax, refraction, and lack of clarity.
Think about how you want to set zero on your rifle for later use with only iron sights. What Reid is saying is that you may not be able to co-witness the irons with the glass if both are to be correct.
Good point. I’d like to take one of Reid’s classes.
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On December 28, 2022 at 10:32 am, HouseWolf said:
I have used the older aimpoint comp series as well as the newer aimpoint pro red dots, co- witnessed with no issues. Same POI regardless. They are essentially parallax free systems.
Certainly not all red dot systems are as good, as the trijicon mro has considerable parallax issues.
On December 29, 2022 at 10:38 am, Thomas Madere said:
Zero the red dot then use the red dot as the zero point for the irons, simply adjust the irons so the red dot sits on top the front sight post when using the irons. It is also can be used to check the zero of the red dot if it was removed and reinstalled.
On December 29, 2022 at 10:53 am, Herschel Smith said:
@Thomas,
If you do that with an optic that has parallax, or lenses that are off-plane, or has other issues, and you remove your optic because it has failed in order to use iron sights, your iron sights won’t be point-of-aim / point-of-impact.
That’s Reid’s point.
On December 29, 2022 at 4:26 pm, Miles said:
For those whose eyesight is still good enough to let them use dots, this is good advice.
I have almost completely switched to LPVO & 1X prism sights due to the effects of age and also the capability of adjustable focus eyepieces to compensate for, and to make it so that I can use my rifles without having to wear my reading glasses.
As it is, the LPVOs I have are of a size that not just co-witness, but any use of back-up iron sights is impossible until the scope is removed (& I have QD mounts to facilitate that) but I do have one AR ‘pistol’ with a prism sight that I will have to check out to see if this effect occurs.
On December 30, 2022 at 1:32 am, Georgiaboy61 said:
The style these days seems to be to load as much crap onto your carbine as possible, from lasers to lights to the kitchen sink, for all I know…. but I come from the old-school and was taught about hunting, fishing, camping and the responsible use of firearms by the men of the WW2 and Korean Wars.
Those men generally believed that a long gun ought to be as “slick” and clean of extraneous attachments as possible. It would shoulder better, balance better, point better and aim better if it wasn’t loaded down with everything under the sun, and the same for carrying it slung, too. That went for grand-pa’s old 12-guage shotgun he used for duck hunting, your dad’s bolt-action hunting rifle, or that old M-1 Garand he bought from the CMP.
Apart from specialist uses, i.e., people who clear structures for a living, the average person most of the time has no need of all of that stuff hanging off his AR carbine. In the field, extra ounces on your rifle add up to pounds before you know it, and you’ll regret loading your rig with all of that stuff once you’re carried it all day. Ditto as you get older but only worse, since you probably don’t possess the strength and stamina you once did.
BUIS (back-up iron sights) complicate mounting and zeroing an optic. A much more workable system, IMHO, is to adopt a folding forward sight – thereby eliminating the need for co-witnessing with your optic – omitting the back-up rear sight altogether. This is carried in your kit per-zeroed and can mounted if necessary after removing your QD-mounted zero-hold optic.
Rather than use a folding rear BUIS such as a Magpul I much prefer to use a standard removable carry-handle AR 6/3 sight, which has been zeroed ahead of time. If the optic has been trashed or isn’t working, quickly remove it and install your carry handle, tightening down the thumb screws. Flip up your folding front sight, and you are good-to-go.
If you prefer, use a standard fixed AR front sight and just worry about mounting your optic high-enough to clear it when you use it, or if you like cowitnessing, set it up that way (I don’t happen to care for the practice, but YMMV). Regardless, just dealing with one sighting system at a time is far-simpler and less hassle.
On December 30, 2022 at 10:03 am, Thomas Madere said:
Quote, If you do that with an optic that has parallax, or lenses that are off-plane, or has other issues, and you remove your optic because it has failed in order to use iron sights, your iron sights won’t be point-of-aim / point-of-impact. Quote
If parallax does exist it is only apparent when the dot is viewed off the center of the optic window. If the dot and irons are sighted in with the dot in the center of the optic then parallax is of no concern for the irons. You wouldn’t sight in the dot with it at the edges of the optics window, you would sight it in with it in the center of the window coaxially with the irons.
A simple definition of Parallax: a noticeable shift in reticle placement while looking through your scope at different angles If you notice your reticle is moving off target while changing your viewing angle, that’s parallax. You need to adjust for parallax to ensure your reticle will be accurate at any viewing angle.
You can’t view irons from different angles like you can with scops and dots.
On December 31, 2022 at 9:32 am, Latigo Morgan said:
Reid is one trainer I’d like to take a class or two from. His prices are reasonable, too.
I’d been bugging him in his youtube comments to do his drill using his Garand, but he hasn’t paid any attention to that, yet. I think it would be a hoot. I’ll probably try it with mine when the mud dries up out where I shoot. Or, I guess I could do it in the mud like our men did in Europe during WWII….