Question on BUIS

[triggerjerk]

Fudd here. When red dots 1st came out, an LE buddy told me "fine until dark and the perp runs in front of a bright lighted sign and you lose your red dot aiming point. Couple of decades later, I had an AR with flip up irons. Got tired of acquiring front sight through a peep on that blaster gun. Ground the top half off of the big hole to make an open rear sight. Kinda liked it for bottles and cans. Ended up putting it on a co witnessed red dot ar pistole not long ago. In darkness I can flip irons up and still easily use red dot without rear peep interference. As I swing from dark to a light, transition to irons is automatic. On the back porch anyway.....

[Disciple]

The bottom line is we may need to get the next shot off too quickly to bring iron sights into the fray if our optic gets disabled. Train using the tube of the optic as a sight. If you've got a FSB rifle, where does it hit if you center it in the tube?

If your tube is a jagged hunk of metal you cant see through, traditional railed mounted BUIS aren't going to do you much good. If you have nothing else, how well do you shoot 'stance-directed' looking alongside the barrel?

My view through a lower 1/3 mounted Romeo 4 or 5 to a midlength-FSB puts the bottom of the window almost perfectly even with the shelf of the front sight when the red dot is at the tip of the sight post. I think that is a useful reference alignment if I don't have time to raise the rear sight.

I haven't tried shooting with a fully occluded red dot. Is it better to keep both eyes open and ignore the sights entirely, trusting motor memory of the alignment, or roll the gun and try to index off the the handguard and barrel? I probably couldn't hit the broad side of a barn in either case.

[ABNAK]

My view through a lower 1/3 mounted Romeo 4 or 5 to a midlength-FSB puts the bottom of the window almost perfectly even with the shelf of the front sight when the red dot is at the tip of the sight post. I think that is a useful reference alignment if I don't have time to raise the rear sight.

I haven't tried shooting with a fully occluded red dot. Is it better to keep both eyes open and ignore the sights entirely, trusting motor memory of the alignment, or roll the gun and try to index off the the handguard and barrel? I probably couldn't hit the broad side of a barn in either case.

That would be the modern-day equivalent to the Armson OEG of Son Tay Raider fame. It was designed to shoot with one eye open, and the same principle applies to an Aimpoint with the front lens cap closed.

It's been 20+ years ago that I had an Armson OEG on an AR carbine. It was cool for a "quick-shoot" CQB type of range (the dot was rather large, like 4MOA) but an actual non-occluded red dot was more accurate. Back then I shot a good deal more than I do now and noticed the difference, more so the further out you went.

[Disciple]

That would be the modern-day equivalent to the Armson OEG of Son Tay Raider fame. It was designed to shoot with one eye open, and the same principle applies to an Aimpoint with the front lens cap closed.

I should have been more clear. By "fully" I meant with both ends covered, simulating "your tube is a jagged hunk of metal you cant see through" as 26 Inf was talking about. I have tried the front lens covered and phoria makes it a poor option for me at more than across the room distances.

[davidjinks]

My personal opinion is……this is a direct representation with the ebbs and flows of the “gun community”.

Some dude/dudette/group/HSLD shows up with the latest and greatest gadgets or shows up without a particular piece of kit. When this happens, a lot of people just have to jump on it.

I have BUIS every rifle that has an optic. Hell, I have BUIS on rifles that have 2 optics. My thought process is; they’re light, small, low footprint, and they’re there when you need them. If you don’t need them, great, if you do, thank god you have them.

So Ive been noticing over the last few years that more and more people aren’t running BUIS on their AR and solely relying on the optic (red dot,lpvo,etc) is this the new trend? And are they obsolete now? Curious on thoughts.

[Molon]

That would be the modern-day equivalent to the Armson OEG of Son Tay Raider fame. It was designed to shoot with one eye open . . .

The Armson OEG gunsight was not designed to shoot with one eye open. It’s reason for being was to be able to aim with both eyes open. From Armson’s website:

“The O.E.G., or “Occluded Eye Gunsight” uses the brain’s ability to “blend” two images- it superimposes the red dot on the object you are looking at. This requires that both eyes remain open, which most shooters agree is tactically better at closer ranges.”



If you tried to aim with just your non-dominant eye open, you wouldn’t be able to see the dot.





If you tried to aim with just your dominant eye open, you wouldn’t be able to see the target beyond a few yards. If there was an armed combatant inside the doorway on the right side of the structure you wouldn’t be able to see it.





…

[Uncas47]

The occluded red dot (front lens cover on) also has the advantage of not having to constantly adjust brightness in varying light conditions. My house gun has it on, dark room, bright room, white light on or off makes no difference, the dot remains the same. Only a bright light from the rear will affect it, but still shootable.

[GTF425]

My house gun has it on.

Same; and for the same reasons you noted. Never washing the dot out with the weapon light or in changing lighting conditions is a big advantage for a home gun.

For the guys who run bino NODs; you can still aim with the RDS and use an IR light if you run the front cap closed. Nice tool to have in the toolbox.

[Molon]

Occluded-eye sighting also has a significant disadvantage of decreased precision and huge point-of-impact shifts due to phoria, depending upon the individual's eyes.

The Effects of Phoria When Using the ACOG as an Occluded-Eye Gunsight






Phoria: the visual effect that occurs when one eye is blocked from seeing the same view of a target as the other eye; the blocked eye does not get the same sensory input as the other eye and can begin to wonder off, usually to one side or the other.

I installed a Progressive Machine and Tool flip-down front lens cover on a Trijicon TA-11 ACOG.. With the lens cover in the up position (blocking the view through the scope) the ACOG can function as a non-magnified occluded-eye gunsight; functioning more like a non-magnified red-dot sight, than a magnified scope. However, when the ACOG is functioning as an occluded-eye gunsight, the view of the target for the eye looking into the scope is blocked and the effect of phoria comes into play.











In order to determine just what the effects of phoria would be when using the ACOG TA-11 as an occluded-eye gunsight, I conducted a test comparing the accuracy and points of impact when shooting with the lens cover down (normal sighting) and the lens cover up (occluded-eye sighting.) Testing was conducted at a distance of 25 yards, the farthest distance that I would anticipate using the occluded eye-method of sighting.

Shooting off of sand bags, I zeroed the TA-11 for point of aim equals point of impact at 25 yards using the normal sighting method. I then fired a 10-shot group with the normal sighting method that formed a tidy group with an extreme spread of 0.56”.







Next, I placed the lens cover in the up position, transforming the ACOG into an occluded-eye gunsight. The left eye views the target, while the right eye views the reticle in the scope. The right eye is blocked (occluded) from seeing the target due to the lens cover. The impact of the initial shots using this method had such a large horizontal deviation to the left that they were off the targets that I originally was using. I had to change to a 24” wide target and aim at the far right side of the target to capture the impact of the rounds. The aiming point for this portion of the test was the numeral “7” on the target.

Using the occluded-eye method of sighting, I fired a 10-shot group. This group had an extreme spread of over 7” and the center of the group was 14” to the left of the aiming point!






….

[Uncas47]

Occluded-eye sighting also has a significant disadvantage of decreased precision and huge point-of-impact shifts due to phoria, depending upon the individual's eyes.

The Effects of Phoria When Using the ACOG as an Occluded-Eye Gunsight






Phoria: the visual effect that occurs when one eye is blocked from seeing the same view of a target as the other eye; the blocked eye does not get the same sensory input as the other eye and can begin to wonder off, usually to one side or the other.

I installed a Progressive Machine and Tool flip-down front lens cover on a Trijicon TA-11 ACOG.. With the lens cover in the up position (blocking the view through the scope) the ACOG can function as a non-magnified occluded-eye gunsight; functioning more like a non-magnified red-dot sight, than a magnified scope. However, when the ACOG is functioning as an occluded-eye gunsight, the view of the target for the eye looking into the scope is blocked and the effect of phoria comes into play.











In order to determine just what the effects of phoria would be when using the ACOG TA-11 as an occluded-eye gunsight, I conducted a test comparing the accuracy and points of impact when shooting with the lens cover down (normal sighting) and the lens cover up (occluded-eye sighting.) Testing was conducted at a distance of 25 yards, the farthest distance that I would anticipate using the occluded eye-method of sighting.

Shooting off of sand bags, I zeroed the TA-11 for point of aim equals point of impact at 25 yards using the normal sighting method. I then fired a 10-shot group with the normal sighting method that formed a tidy group with an extreme spread of 0.56”.







Next, I placed the lens cover in the up position, transforming the ACOG into an occluded-eye gunsight. The left eye views the target, while the right eye views the reticle in the scope. The right eye is blocked (occluded) from seeing the target due to the lens cover. The impact of the initial shots using this method had such a large horizontal deviation to the left that they were off the targets that I originally was using. I had to change to a 24” wide target and aim at the far right side of the target to capture the impact of the rounds. The aiming point for this portion of the test was the numeral “7” on the target.

Using the occluded-eye method of sighting, I fired a 10-shot group. This group had an extreme spread of over 7” and the center of the group was 14” to the left of the aiming point!






….

Not my experience at all, I also don't have a 25 yd problem in my house. It's a specific application for me, not general usage. I also have a lot of time on the gun this way, it's not a one time event.