why do we need Co-Witness Sights?


February 3, 2011, 10:48 PM
I've seen this in a few posts lately and most recently a rifle was downgraded because it lacked the capability to "co-witness".

So my understanding (and I might be wrong) is that you can simultaneously use a scope with your iron sights to make sure everything is lined up. Is that right? If so it sounds like a waste of time.

If my assumption is wrong then I'm clearly off base but if not I'll trust my scope till it fails me. Then I'll rip it off and go to the irons. Why would I spend time lining up my irons with my cross hairs (or red dot)?

Please help me understand and thanks in advance.

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February 3, 2011, 11:01 PM
Co-witness, at least by my and many other's definition, is such.

Have a red-dot or halo type sight for primary use.
Have back-up iron sights that are able to fold down. (At least the rear folds down)
Use red-dot/halo type normally
If battery dies or something happened to make the red-dot/halo go way off point of aim; flip the sight up and look through the iron sight. The red-dot/halo type sight, being it uses infinite eye relief, allows you to see right through it so you can focus on the front sight. Basically, like the red-dot/halo wasn't even there.

Now there may be some that try and use an iron and red-dot/halo simultaneously. I don't know anyone who does. But I do know plenty with backup iron sights. If they 'CO-Witness, you don't have to remove the red-dot/halo prior to using the irons. There are some iron sights that are too low/high and might not allow you to see through the red-dot/halo. OR, you have a regular scope that requires normal close eye relief. Co-witness simply allows you to use iron sights without having to remove the red-dot first, when the battery dies.

Again; this is how I use the word co-witness, and this is how I define it. If someone else defines it differently, I'd like to know. As for using both the red-dot and irons simultaneously, I agree, that sounds really silly.

February 3, 2011, 11:08 PM
My duty AR has a Trijicon Reflex mounted on one of those carry handle spoon mount things. I still have the iron sights....Heck, I need them just to make sure the red dot is in the right place because that mount is flimsy and will move............Anyway, I look over the iron sights at anything under 50 yards and use the dot. Past 50 yards, I prefer the iron sights, however, the dot is annoying and kinda covers the front pin. I wish I had the option to turn it off.

February 3, 2011, 11:15 PM
As I understand it, "co-witness" is useful on non-magnifying optics, like Eotecs. On magnifying red dot optics co-witness usually becomes problematic at best.
If there's someone with more knowledge than I have feel free to correct me.

February 3, 2011, 11:43 PM
christcorp said it best. All I'll add is that if the reflex fails, the "window" makes for a decent big a$$ed rear peep without flipping up your rear BUIS. I wouldn't want to shoot a 200yd match with it, but for up close and personal it works fine.

February 4, 2011, 09:04 AM
Co-witness means being able to see the iron sights thru a red dot and still be able to use them IMMEDIATELY if the optic fails. Why? Because in the rough and tumble world of combat, optics fail.

Exit a combat hatch on a vehicle, and the optic bangs on the jamb. It's barely inches wider than the soldier. Third world country, no building codes or ADA mandates for wheelchairs, same thing. Some of those buildings have been standing for centuries, don't expect them to be a walk in the Mall. Five foot high doors two feet wide are normal.

And for some reason, the other guys like to shoot bullets and explosive devices at you, high speed pieces of steel and concussive overloads aren't glass optic friendly. You don't wait to take off a scope, or flip up sights, you need to shoot NOW.

It's not a quiet Saturday at the range. If it is, or they hunt, then relying on a scope that might fail isn't life and death. If the firearm is conflict oriented, cowitness is an edge.

It's one of the specific things done for combat firearms, like a lot of race gun or long distance precision stuff, it may not be any help at all on a hunting or plinking rifle.

February 4, 2011, 09:23 AM
From everything I've read, co-witnessing an unmagnified red dot or holographic optic with irons is almost always done on some sort of combat rifle/carbine. Most often referring to the AR15.

Whether it's 1/3 lower or absolute the idea is that you can transition immediately and effortlessly to your irons should your red dot fail. All of this can be down while having the red dot at the same height above the bore thereby giving you the same cheek weld as you would shooting irons. In theory and practice this works well and makes transition effortless.

Is it needed? How much insurance do you tend to purchase? For a carbine that is intended or has the chance to be defensive or even offensive weapon I would say it is highly desirable. For hunting or general plinking not at all.

If you are talking about traditional glass scopes the general consensus is to just have a folding BUIS ready to roll should the glass optic fail. You will not be able to see co-witness sights well enough through a magnified (glass) optic (even at 1x).

February 4, 2011, 12:49 PM
Even the best optic can fail. Tirod said it best. At the range it is a pain in the ass. On the battlefield it ends with you being dead.

Damage, bad luck, an EOTECH which has gone dead for whatever reason... All these are times when you want a set of BUIS that are properly co-witnessed.

February 4, 2011, 12:51 PM
So my understanding (and I might be wrong) is that you can simultaneously use a scope with your iron sights to make sure everything is lined up. Is that right?

No, it's in case the optic fails you can continue to fight with the irons with no downtime.

Do most of us need that functionality? Probably not but personally I don't find it annoying on my rifles. When I'm using the optic the front sight post sort of fades away and I don't even notice it unless I intentionally focus on it.

February 4, 2011, 02:20 PM
While I understand why it would be important in armed conflict, for my purposes, I want my sights flipped down out of the way.

February 4, 2011, 08:49 PM
I appreciate all the responses. My understanding of Co-witness was obviously not correct and given the concerns with red-dot failure in combat I think I get the concept. It's not something I need but I do appreciate learning new things here and there.

Maybe it just needs a better terminology than "co-witness". Just a thought. For those of you in combat, thank you for your service and come home safe.

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