Co-witness iron sight on my AR - Why can't I see it?

[gunsrfun1]

I'm embarrassed to ask this question, but I am stumped.
I added a front sight to my AR with a 2-7x32 Burris scope. No real need for a front sight per se, but I thought it just "completed" the gun. Tacticool.
My understanding of co-witnessing is as a backup iron sight in case your optic fails.
So ... I look through the scope, and cannot see the iron sight at all, at any power.
You can see from the photo that the front sight post is in line with the horizontal axis of the scope. So I would think I would be able to see the post, or at least some part of the iron sight, like the ears.
But I can't.
Is that because even at 2X, the magnification is too large to get a sharp image of the iron sight at that short distance, and the magnification is "washing out" the iron sight?
And if that is the case, why have a co-witnessed iron sight on the gun if I can't see it?
Obviously I am missing something here (no pun intended.) Can someone explain this?
Thanks

 

[Varminterror]

Yup, even 2x is too much for cowitness.

Why have irons to cowitness at all? Well, don’t try to cowitness with a magnified optic… or, like the rest of us running BUIS’s with scopes, just remove the scope and flip up the irons if something happens to the glass.

 

[rabid wombat]

Smarter people will respond shortly. I have only dealt with cowitness issues with 1x optics like Aimpoints and etc. When the dot ‘dies’, your cowitness is either true or bottom third. I learned on bottom third….

Probably too much magnification in your case…..

 

[shoobe01]

Optics have a range in which they can focus (depth of field). If you could focus down to see the front sight (and you can't because scopes are optimized to likely ranges and that would be useless for adding money size and weight), you could also see a bit closer and maybe to 4 feet away, but you couldn't see any likely target.

Co-witnessing the irons is for RDS, to transition or to immediately fall back to emergency sights when the RDS fails.

Also, you don't have iron sights. You have iron sight. There's no obvious value to having just a front post. If you must have backup irons you need folding front and rear, and a quick-detach scope mount, so if the optic goes bad, you remove it, then shoot with irons. But... there's no obvious reason a scope would go bad. I'd just remove the front sight, and put it in a nice bag, in the box of spares. Problem solved!

 

[LonewolfMcquade]

Wont work through magnification.

 

[rabid wombat]

I'd just remove the front sight, and put it in a nice bag, in the box of spares.

And have it grow up into another AR….it works like AR seeds, scatter them about and they grow into another

 

[gunsrfun1]

OK thanks all. So basically, to put it bluntly, this particular set-up makes no sense, because:
1) I can't see the front sight because it's too close to the scope, since the scope is optimized for longer distances. Only way to see it would be to remove the scope.
2) I really need a front and back sight to make a co-witness scenario work.
3) Ideally I should have the scope mounted on a quick release mount, should I have to remove it
4) It's unlikely the scope will fail.
Let me know if I missed anything. Otherwise, I'll be removing the front sight.
Thanks again.

 

[Dave DeLaurant]

I think you've got the gist of the focusing problem now. Some of my low-powered scopes will pick up the front sight (or the hood) as a 50 MOA blur at the bottom of the field, but that's hardly a useful co-witness.



FWIW, I've got a cheap non-magnified red dot on my PAR that's the right height to co-witness with my irons just fine. However, other than confirming that both sighting systems are in agreement, I can't really imagine using the irons at the same time unless the electronics fail and I need to take aim through the tube in a big hurry.



I think having irons mounted as a backup to an LPVO isn't a bad idea, but I think you'd want a QD scope mount and both folding sights mounted. It doesn't look like you have the rail estate to keep the rear mounted on your rifle, so I'd be inclined to ditch the irons for now.

 

[Varminterror]

3) Ideally I should have the scope mounted on a quick release mount, should I have to remove it

Eh, not really necessary. Any mount with 1/2” nuts, especially with keyholes and driver slots, offer multiple options for removal in the field. Mounts using common screw options are pretty easily removed by an onboard tool kept in some part of the rifle. QD mounts certainly make it easier, but certainly aren’t required.

But personally, I’d ditch the front sight and forego irons at all. Co-witnessing and back up irons are largely a dead meme without relevant pertinence.

 

[LoonWulf]

While I can understand the desire to have BUIS....IMO

This

Eh, not really necessary. Any mount with 1/2” nuts, especially with keyholes and driver slots, offer multiple options for removal in the field. Mounts using common screw options are pretty easily removed by an onboard tool kept in some part of the rifle. QD mounts certainly make it easier, but certainly aren’t required.

But personally, I’d ditch the front sight and forego irons at all. Co-witnessing and back up irons are largely a dead meme without relevant pertinence.

+1

I do keep irons on any AR thats running a red dot, but I dont see a reason to have them on a gun with a scope.


I keep a small set of allen wrenches for my dads AR in the grip, shoved them thru a block of foam to keep em from rattling. Iit allows me to adjust his stock, or even swap his scope with a different one in the field.

 

[RainDodger]

A back-up sight on the front is fine. When I look at your rifle, I just kinda figure you need a back sight to go with it.

 

[Choctaw]

If you want BUIS with that set up just put 45 degree irons on.

 

[herrwalther]

Essentially, magnified optics sit above and look through your backup iron sights. Even with a 1.5X you are not going to see your front sight. Backup irons really shine when you are using a red dot. You can look through both sets of sights in the same plane, with no magnification.

You still can use a scope and backup irons. You just have to remove the scope. Ideally this is done with a quick detach mount. In another life we had soldiers with ACOG 4x scopes with backup irons. The ACOG was on a QD mount that could be detached with thumb pressure, just in case an ACOG failed.

 

[Skylerbone]

I’m down to 2 that can co-witness, one with folding MagpulBUS, the other with FSB and Troy fixed. I used to feel the need on all of them but yeah, how often does a decent scope fail…

 

[sarduy]

Co-witness only work well with 1x or with reddot, the idea of co-witness is that if your reddot/reflex sight fails you can pop the front and rear sight and continue to run the rifle. If you are running any other magnification greater than 1X you can use what’s called Offset sights, which bring the sights to a 45 degrees of center and you can use the sights in case the optics/scope fails.

 

[Skylerbone]

Here’s your progression: normal optic use, emergency co-witness, optic removal. Most BUIS are ridiculously overpriced to begin with and offset tend to increase that cost with another 40-50% premium.

That puts you in the range of something like a Burris FF III which you could have stashed in a range bag or if you’re really concerned, use an adaptor scope ring to mount it off to the side. So many great modern solutions that don’t cost an arm and a leg.


Standard shooting.


Optic dies in a crunch.


You’ve got a moment to remove your RDS and carry on.

 

[JShirley]

If you want BUIS with that set up just put 45 degree irons on.

This. I typically have co-witness on unmagnified red dots, and have a couple of 45° sights on ARs with magnified optics. I do see value in having backup irons, but to me, the whole point of having BUIS, is to be able to instantly transition. This could be because your target is very close, or because you've had an optics failure. Removing your scope is in no way "instant".

I do see some potential value in being able to spot your front sight at very close range*, but would not expect to be able to see it through a magnified optic.

*when practicing reactive fire in the infantry almost 20 years ago, we were taught at very close range to swing our weapon up until the front sight covered the target and squeeze.

John

 

[JShirley]

.
But personally, I’d ditch the front sight and forego irons at all. Co-witnessing and back up irons are largely a dead meme without relevant pertinence.

What is your training and experience that leads you to this conclusion? I'll happily accept competition shooter, or small unit LEO or military.

John

 

[wiscoaster]

Getting a cowitness properly setup and zeroed for both, not even to mention working with that sight picture, is such a pain in the ass that I prefer to use red dots with QD mounts, and flip-down irons, so I use one or the other, not both together. (Plugging ears for the jeers coming my way).

 

[JShirley]

There is probably a lot of difference in planned mission for those of us that want most of our AR-15s to be potentially fighting rifles, as opposed to a purely recreational setup. If I expect my rifle to be purely a range toy, I can have whatever combination of nonsense I feel like. If I want it to be able to save my life, I probably have more rigid criteria. When I bought a new optic for one of my rifles yesterday, I spent the 50% extra for an etched glass reticle, all other options being identical.

 

[wiscoaster]

Range toy.

 

[Varminterror]

In the context of a civilian talk forum, I don’t expect many folks are planning missions into enemy territory, and de-evolution of a civilian scenario into demand for BUIS is pretty convoluted.

 

[Bcwitt]

I would perfer an optic that was removable. I generally do not use an optic w an AR, but if i did, it would in no way be primary to the best iron sight arrangement i can devise. Im a bit of an iron snob. I veiw optics as a crutch. With that said, a 1x to 1.5x is about as good as it gets in the under 300m zone.

 

[herrwalther]

Getting a cowitness properly setup and zeroed for both, not even to mention working with that sight picture, is such a pain in the ass that I prefer to use red dots with QD mounts, and flip-down irons, so I use one or the other, not both together. (Plugging ears for the jeers coming my way).

Easier than you think. Especially for absolute co witness. Zero your red dot then adjust your see through BUIS to the red dot. Shut off red dot (to simulate failure) and zero the irons. If you do the job you should be on or really close to where your red dot was hitting with your backup iron sights. We called it "lollypop" the sight.

I did not like lower 1/3 co witness. When Army doctrine got caught up to allow shooters to choose either, by picking the right risers. I shot it a few times to give it a try but stayed with absolute. And mimicked a similar setup on my civilian rifle.

 

[JShirley]

In the context of a civilian talk forum, I don’t expect many folks are planning missions into enemy territory, and de-evolution of a civilian scenario into demand for BUIS is pretty convoluted.

Sure. Maybe your 2nd Amendment protects different freedoms than mine does

No "devolution", no matter how much you want to torture one out. Even many older hunting scope mounts were see-through, to allow using the irons if there was a problem with the scope. If the OP thought he might want to use the front sight- which I understand- we are speaking to his intent. And you don't know "his scenario". More people almost certainly buy AR15s for home defense than anything else, and (IMO) a defensive rifle with only an optic and no irons is just plain foolish.

You stated a definitive opinion-"Co-witnessing and back up irons are largely a dead meme without relevant pertinence" absent of context. Now, you want to attempt to add context? No. Maybe you misspoke originally. Personally, I think you stated an opinion on a serious subject without the knowledge or background to make such a statement. I gave you the opportunity to explain why your opinion on such an important topic was valid, and you got defensive- demonstrating that your opinion was not an informed opinion, and therefore, was without value.


John