I recently raised the question in another thread of whether it would be possible to shoot accurately if it wasn’t possible to see the target through an optical sight, specifically a “red dot” type mounted on a handgun. The scenario envisioned there was that only the front window or lens of the sight was obscured by something like firing residues blown back through a hole in the barrel hood extension of a SIG pistol. It therefore assumed that there would be no interference with projection of the reticle onto the rear element of the sight due to rain, snow, etc.

In response to my question it was stated that it would still be possible to aim the gun due to a particular visual phenomenon. If the shooter looks at the target with both eyes open and the front of a sight with an illuminated reticle is blocked, our brains will automatically combine what we see with the two eyes into one visual image. In that situation, if our dominant eye is seeing the reticle without being able to see the target through the sight, the brain will combine the reticle image with what we see (i.e., the target) with our nondominant eye.

That phenomenon is easy to demonstrate by simply looking at a target with both eyes open while blocking the front of the sight. We should see both the target and the illuminated reticle (dot or other). And because the reticle appears to be superimposed on the target as usual, we should be able to aim and shoot accurately as well—correct? That’s what I decided to determine for myself.

As I posted in the other thread, I originally conducted experiments with four sights that I mounted firmly with the reticles aimed at distant points. The sights were an ACRO P-1 and CompML3, both Aimpoints; a Leupold “Prismatic;” and a 3-15× riflescope with illuminated reticle. In every test when I blocked the front of the sight, I could still see the reticle with my dominant eye and the “target” with the other eye, but the reticle immediately and very significantly shifted position with respect to the target. With the ACRO positioned at arm’s length from my eyes, the shift was about a foot at 10 yards. The results of those experiments led me to believe that accurate fire with those sights wouldn’t be possible if the view through the sight were blocked at the front.

But I was only going on what I observed. Today I conducted a live fire test.

The test gun was an AR-15 chambered for 223/5.56 and the sight was an Aimpoint CompML3. Ammunition was Federal 55 grain FMJ AE223 (223 Remington). Weather conditions: overcast, wind calm, temperature upper 30s. I fired six three-shot series, three from a rested position using firm bags on a table, and three series offhand (standing unsupported). Two Post-It notes and a small target repair paster were used as aiming aids. The results:





1. Rested, 25 yards, looking through the sight normally.

Not numbered. Rested, 25 yards, front lens cap closed to prevent looking through the sight. Aiming was by using the superimposed images from my two eyes; right eye saw the reticle, left eye saw the target. That string was not numbered on the target because none of the shots hit the paper anywhere. Note that the cardboard backing sheet is 24 inches wide.

2. Offhand, 25 yards, lens cap closed. As indicated, only one of the three shots hit the target backer.

3. Rested, 15 yards, looking through the sight normally (and yes, that hole was made by three shots).

4. Offhand, 15 yards, lens cap closed.

5. Offhand, 15 yards, looking through the sight normally. That group isn’t the best I’ve ever fired in my life and my offhand skills have deteriorated significantly over the past 60+ years, but it was far better than number 4 pattern.

So, what to make of the results. As is clear, the rifle and ammunition are capable of good precision when shooting from a good rest and using the sight normally. Trying to use the superimposed image of the reticle on the target when it’s not possible to see through the sight: actually far worse than I expected even based on the previous tests, and totally unacceptable.

Not only does the apparent position of the reticle move (a lot!) when using just the combined visual images, but it was very difficult to aim consistently that way. The very slightest movement of my head, or even my eyes caused the reticle to shift and wander around on the target. When shooting with the front lens cap closed I did my best to try to fire when the reticle wandered back to the same spot as previous shots, but I wasn’t really ever very successful.

As I also mentioned in the other thread, and as is to be expected, the effect of the reticle shift when trying to use the combined visual images of reticle and target increases with target distance. I don’t currently have an optical sight mounted on a handgun to use at close distances, but I would expect any reticle shift to have less effect than the results I saw today. I will also point out, though, that users of optical sights on handguns commonly state that at close distances point shooting methods are more commonly used than aimed fire, and the primary advantage of such sights is greater accuracy at long distances.

I may have a chance to repeat the above experiments with a handgun mounted optical sight, and I’ll report the results when/if I am able. I would be very interested in anyone else’s experiences with shooting aimed fire when it’s not possible to see through an optical sight. If anyone expects to use the occluded sight method in a serious situation, I strongly urge them to conduct experiments to see how the technique would work in actual practice.

As a final comment, this post relates to the types of sights and conditions explained. It has nothing to do with using a sight like the Armson OEG that always blocks the vision of one eye. And for those who obsess over such things, I posted this in the pistols section because the primary interest is in sights mounted on handguns and which are much more likely to become obscured than rifle sights.

This message has been edited. Last edited by: sigfreund,

I haven't done formal testing as you have, but I have not had problems hitting intended targets with the Aimpoint Micro's front end completely covered. This is no doubt because of the two-eye open and looking at the target (not at the dot). This is AR shooting, btw.

I know some pretty fast guys who shoot in our weekly pistol matches who run an occluded sight as a training exercise and they don't seem to suffer much from it.

quote:

It has nothing to do with using a sight like the Armson OEG that always blocks the vision of one eye.

....

It is exactly the same as using an OEG. Some people experience dramatic phoria when trying the bindon aiming method, you seem to be off the charts.

It is better used in dynamic circumstance aka movers. I've hit small movers with the OEG @ 200m and the same with the aimpoint 5000 with the front cover up... and the later comp series.

Also, used the front lens cover up on an illuminated luepy 1.5-5x to create a defacto dot sight for short range fast option.

best zero can be had by setting in position, looking down and then up at the target and snap shot as soon as dot on target.

Done the same with the T2's on a glock... And also when a large suppressor blocks the front sight or red dot.

doesn't work for everyone

Maybe I’m reading this wrong but if I’m not you might be doing something wrong. I read it as an Aimpoint on an AR with the front cover in place.

I don’t have that particular optic but I have 2 Aimpoint PRO’s which are close enough to call them the same. I have optics covers and have shot many times with them down in place. In fact the covers are opaque for the front and clear for the back. Literally designed to be used in place if needed or desired.

I have never noticed any issue whatsoever hitting and grouping in this manner. Something else happened in your test that caused that. No disrespect but this is a you (physiologically speaking) issue not an actual optic issue.

I've shot occluded optic plenty in the past year. While it was mostly fast, dynamic type shooting and not slow-fire precision work, I was able to keep rounds in an 8" circle pretty easily from 5-10 yards with a handgun. I have not done it as much with a rifle.

It's an interesting test and I'd be happy to add some data points to your study if I have time to make it out to the range tomorrow. I'll try to take along a handgun and a rifle just to see if it makes a difference with my eyes and technique.

I was first exposed to this technique in a Pat Rogers class 20 or so years ago. Pat called it “the superior use of bi-nocular vision”. (You had to know Pat).

Since that time, it’s carried over to pistols with me and has become a major training aid for me. A major error that a lot of users make with the MRDS is they attempt to “aim” the dot versus looking at the spot where you want the round to go and superimposing the dot over that spot. I personally shoot way worse groups if I close an eye and try to “aim” the dot, instead of looking specifically where I want to put the bullets and applying great trigger control.

That being said, training with a front occlusion is one of the best ways to learn to shoot target focused instead of dot focused. I train that way a lot. Particularly in dry fire. I keep a roll of painters tape in my range bag for just such training.

A lot of people believe that you just throw a dot on a pistol and that’s that. There are nuances enhance the dots performance. I’m a firm believer in target focus shooting. People have some weird ideas about what target focus is, but when done correctly it’s fast.

It’s good to hear of others’ experiences, but I’m curious what I could be doing wrong.

I fix the sight in position, position the image of the reticle on a clearly-defined spot, without moving anything close the front lens cover or otherwise cover the optic so I can’t see through it, and now the reticle’s apparent position on the target has moved. When I shot my rifle today with it on a rest, it was obviously fixed firmly enough that I was able to produce the two reasonably-decent groups at the expected points of impact as shown above. When using the exact same rest and trigger control technique with the superimposed images of the target and reticle, the hits were widely scattered or shifted so far that they were not even on the paper.

I long ago learned that the proper method of using sights like that (and others) is to focus on the target and move the gun so that the reticle moves to the target. I have taught that concept for years as well, and I don’t just focus on the reticle and then try to find the target. But I obviously must be aware of where the reticle is within my field of view as I’m doing all that and the technique works just as it should when using the sight normally. (Today after the experiments described above, I fired 50+ rounds with the same rifle in drills that required engaging targets as quickly as possible at various distances.) When I’m using the superimposed images, though, the reticles shift position with respect to the target with any slight movement of my head or eyes.

I’m not aware of any vision defect that could account for all that, but I did have cataract surgery in my dominant eye recently: any explanations from the eye experts? (And if that could be the cause, it could be something that others might need to be aware of.)

And although it seems that many here can obtain satisfactory results for their purposes without being able to aim through the sight, I’m curious how many have compared group sizes and exact points of impact when switching between the two aiming methods.

noun. pho·​ria ˈfō-rē-ə : any of various tendencies of the lines of vision to deviate from the normal when binocular fusion of the retinal images is prevented.

This varies widely among people.. as mentioned earlier.

Also, you might try changing the occluded eye to the other side, just for fun.

quote:

Originally posted by sigtacular:
pho·​ria

Ah. Well, that could be it*, I suppose, although I have never noticed any of the symptoms that the Internet says are associated with the condition.
I also have my eyes examined about yearly and it has never been mentioned about me. I will have to ask about it during the next exam.

I can't tell from the one article I read how common it is, but as I say it could be something that other shooters (and instructors) should be aware of if they plan on using the occluded sight technique.

Thank you.

* Nope: See 15Feb24 post about me and phoria.

This message has been edited. Last edited by: sigfreund,

quote:

Originally posted by sigfreund:
It’s good to hear of others’ experiences, but I’m curious what I could be doing wrong.

And although it seems that many here can obtain satisfactory results for their purposes without being able to aim through the sight, I’m curious how many have compared group sizes and exact points of impact when switching between the two aiming methods.

Obviously it's hard to tell without seeing you shoot but I have some ideas that you can play with the next time you are out.

You're trying to aim rather than make hits. You're switching your focus from your dominate (blocked) eye to your unblocked eye, that's why your seeing the shift of the aiming point. Maintain your focus with your dominate eye and and watch the aiming point appear on the target that you're seeing, but not focused on, with your non-dominate eye.

It isn't a pin point technique, trying to make shots fall on the same spot will only result in a jerked shot/slapped trigger....you're becoming overly investing in shot placement

Bear in mind that they only time you'd shoot with the lens occluded would be when you didn't have the ability to clean it off first...which means a slightly off-center hit is better than not firing the shot because you can see through the lens

quote:

Originally posted by 9mmepiphany:
Maintain your focus with your dominate eye and and watch the aiming point appear on the target that you're seeing, but not focused on, with your non-dominate eye.

Perhaps I did not explain it clearly, but that's what I do both when aiming normally by looking through the sight, and when I was shooting with the occluded sight during the above experiment. For that, though, I was also trying for exact shot placement because I wanted to compare the two methods.

I'm pretty sure that I wasn't jerking the trigger in any of the rested series. The 25 yard normally-sighted rested group could probably have been a little tighter if I had been using a much smaller target rather than the large blue Post-It note.

I do a lot of both types of shooting with my rifles: trying for tiny groups at exact points of impact, and getting hits as quickly as possible within a scoring zone without over emphasis on precise hit locations. The latter is what I did with the next 54 rounds after the occluded sight tests. All things considered, I am reasonably content with the results I usually get with both types of shooting.

quote:

Originally posted by sigfreund:

quote:

Originally posted by 9mmepiphany:
Maintain your focus with your dominate eye and and watch the aiming point appear on the target that you're seeing, but not focused on, with your non-dominate eye.

Perhaps I did not explain it clearly, but that's what I do both when aiming normally by looking through the sight, and when I was shooting with the occluded sight during the above experiment. For that, though, I was also trying for exact shot placement because I wanted to compare the two methods.

the fact that you can see the aiming pint "shift" would seem to indicate that you are trying to focus and "place" it

quote:

I'm pretty sure that I wasn't jerking the trigger in any of the rested series.

I wasn't meaning to say that you were during your test. What I was trying to say was trying to "time" the crossing of the aiming point and the desired strike zone usually implies anticipation of movement which can often lead to jerking the trigger

25-30 yards is about my limitation for reasonable groups with a pistol occluded.

FYI

quote:

Originally posted by jljones:
I was first exposed to this technique in a Pat Rogers class 20 or so years ago. Pat called it “the superior use of bi-nocular vision”. (You had to know Pat).

Since that time, it’s carried over to pistols with me and has become a major training aid for me.

Same here, on both accounts although it probably was more like 10 years with Pat. Interestingly, I've no particular deviation with pistol but had a lot with rifle then. I need to check with rifle again. It is also useful in a couple of special lighting conditions but this benefit has little practical value on carry guns unless one is willing to keep it occluded at all times.
I know a couple of strong shooters, M/GM class, for whom it doesn't work.

I did manage to make it to the range this morning and put this to the test.

First, a couple of environmental factors: Did you know that masking tape can freeze? Apparently it can. It was in the 20s this morning, and it had been out in my car all night. I couldn't get it off the roll. Probably didn't help that it got rained on last time I was out. Thankfully there was a piece that I was able to salvage from the front of my binder, but I had to shoot all the occluded handgun targets in one sequence and then go back and shoot the clear optic targets because I only had one piece of tape. I had planned to shoot the clear optic and then occluded optic targets right after each other at the same distance.

All rounds were fired standing unsupported. Target circles are 4.5" in diameter. 5 rounds at each target.

10 yards with the P320



15 yards with the P320



25 Yards with the P320. I sucked on this one, both occluded and clear. 1 round with the occluded sight impacted 2" to the right of the paper, but based on the other 4 I'd say that was definitely me. My clear optic group was more like a shotgun pattern with one round impacting about 3" above the paper. Both "groups" were high...probably due to my 15 yard zero.



Next the rifle. I shot my 16" CMMG RDB 9mm AR, with a Romeo 5 on it. It used to have a Holosun 407C on a riser, but I stole that for my MkIV a few months ago and only recently mounted the Romeo on it. I think I've only had it out once with that optic, just to fire a few rounds to get a basic zero.

When I took that rifle out of the safe this morning I checked to confirm that the optic was working. It was. When I got to the range, it was dead. Thankfully, I had my "range mom" bag with me and had spare batteries in there, which fixed it. This rifle is a range toy, so I don't hold it to the same maintenance standard as some of my others, but it was a good reminder to not rely on the factory battery because you have no idea how old it is and apparently it might be dead in less than 2 months. I do wish optic manufacturers would build some kind of early warning into their sights to let you know when it's about to die, because it was working just fine and then 2 hours later it was completely dead.

I had a front lens cover for the Romeo5, so I didn't have to rely on my frozen masking tape and I was able to shoot the clear glass and then occluded optic strings one after another at the same distance. All rounds were fired standing unsupported.

AR-15 at 10 Yards (ignore my stupidity in not accounting for offset on the first shot. I also dropped one round of the "occluded optic" string about half an inch off the right side of the paper):



AR-15 at 15 yards. Again, I had a round to the right barely half an inch off the edge of the paper. Based on the rest of the group I blame myself.



AR-15 at 25 Yards. Clearly there was a visual alignment issue resulting in impacts to the right, because the group isn't terrible, but they are all off the paper to the right. I took a picture of this one before I removed it from the cardboard backer so you could clearly see the distance of impacts from the center (marked holes are the misses from earlier stages).




Overall, I think the occluded optic theory is workable. There is clearly some shift in point of impact based on the shooter's eye, but the degree to which it occurred wasn't as extreme for me as it was for Sigfreund. Interestingly, though, the impacts were pretty consistent through my entire string of fire, and my drift was consistently to the right with both the handgun and the rifle. I am right-handed and right-eye dominant FWIW.

I observed a greater degree of POI shift with the rifle than I did with the handgun. While shooting I found it harder to get a binocular view of the target around the rifle optic body, as it was larger and closer to my eye than the handgun optic. I'm kind of curious to try mounting it further forward to see if that makes it easier to achieve an unobstructed view of the target with my left eye, and if that provides any change in the point of impact.

Based on my results, I'd say that the technique would still be "combat effective" out to 25 yards with the handgun, and borderline with the rifle at that same distance (assuming the goal is to keep everything within an 8" circle centered on the vitals).

Great effort, 92fstech. Thanks for doing that and posting the results here.

If the condition known as phoria* that sigtacular told us about has its own medical name, then it was obvious that I couldn’t be the only person it affects, and no doubt to different degrees among individuals. That prompted an Internet search for “phoria and occluded handgun sights,” and discussions immediately surfaced in which shooters described experiences that were similar to what I posted above.

As I mentioned, and as optical sights on handguns become more common and shooters are encouraged to learn that they can be used even if the front lens is covered, it’s also important for the condition and its effects be understood. There are any number of YouTube videos in which the technique of shooting a handgun optic with the front obscured is discussed and although I haven’t tried to watch them to determine, I can only wonder how widely it’s recognized that not all shooters can achieve the same results when using the technique as an instructor.

My experience has reminded me of the problem many people have with the lack of clarity of the illuminated reticles in common “red dot” sights these days. It’s usually blamed on astigmatism, but for me the problem became progressively worse over time to the point that I switched the sight on my training AR to a prism type. When I had cataract surgery, though, the problem disappeared immediately. If, however, I’d always had perfect vision and not seen the discussions here about the problem, it would never have occurred to me that an otherwise unrecognized vision defect could be the reason a student was struggling to achieve good accuracy with an Aimpoint sight.

As the song goes, this whole thing has been a lesson to me, and thanks to everyone who contributed to it.

* Nope, that wasn't it: See 15Feb24 post about me and phoria.

This message has been edited. Last edited by: sigfreund,

I wonder if it’s like those magic eye pictures, I have trouble with those as well.

Sigfreund, I'd be interested to see your results with a handgun optic to see if they mirror my own where the POI shift is less pronounced compared to the rifle-mounted optic. I'm curious if there's a pattern there or if it's just something unique to me.

quote:

Originally posted by 92fstech:
Sigfreund, I'd be interested to see your results with a handgun optic to see if they mirror my own ....

I hope to be able to do that at some point. Will post if I do. Thanks again.