So some of you may remember my question recently about an accurate site picture using military iron sites. Thank you to those of you that offered the links to zeroing and accurate site pictures.
Since I last popped up with an AR marksmanship question, I have purchased a set of BUIS (Yankee Hill flip). These sites have been zeroed, using the improved battlefield zero I found on this site, and I am shooting while seated and with a rest at 1 MOA. I have no Red Dot at the moment as I can’t afford one considering the outdoor gear I want this summer, and the fact I feel I need to better understand, and improve with the iron sites before i drop 400+ on a new “flashy bit”.
So here is my question:
All of my shooting at this point has been done with the small aperture. I have 300+ rounds through the gun since I bought the sites, and I am happy with my average regarding hits. I am hitting with in three inches of dead center with every shot while standing at up to 60 yards, while firing every 1-2 seconds (not rapid fire, but semi controlled fire). This is all with the Small Aperture, and an HK style front site.
But, every time I have deployed the big aperture I feel like it is creating an optical illusion that is almost making me see double regarding the site post. All of the circumstances in which I have tried have been at close range, under natural light. I am finding it hard to see the post, but I like the site picture of the large aperture…
Under what circumstances is the large aperture intended for? Is it possible that it is the HK style front site that is making me see double due to the double circle?
Sorry, I’m a bit longwinded. It’s an Irish curse…
A lot of stuff in there; let’s see …
Anything s possible. We’re talking about the influence of eyes (most important) and the brain (second) in resolving the image that is creating a “double post” for you. I have used an aperture rear and circular-post front on two rifles and have never had this problem (one was a target setup, the other was on a Mini-14 with an HK front).
The possible influences could include various eye conditions, the distance your eye is from the rear sight, the design or color of the post, the sight radius (rear to front distance) … you get the idea.
I am assuming you are shooting one eye open. You might try shooting with two eyes open (a good practice in general). This will not directly affect the problem, but will change the circumstances drastically. I’m afraid this is pretty hard to diagnose. I (and others) have had problems with a famous red dot that rhymes with “Schmeotek” and I have taken mine to my eye doctor, who thinks it is a pretty good diagnostic tool when assessing my prescription. As a final possibility, you could just ask you eye doctor.
The large aperture is for rapid sight acquisition at shorter ranges. It is useful for this because it provides a larger sight picture available to the shooter, and, because the larger aperture admits more light, which, in turn, permits the eye to more effectively resolve the reflected light from the target.
Finally, I come from a long line of Emerald Isle exiles and I have the same problem.
Good luck. 
As Amicus said, the large aperture is not built for precision, it is built for speed and gathering light. If you want to hit faster you will need to invest in an RDS of some flavor.
I have a Hadley eyepiece on one of my long range black powder rifles. It has a dozen different apertures on it – each a different diameter. The choice of apertures is strongly affected by the time of day, atmosphere, and angle of the sun (time of year). Small changes in aperture size can make the front sight very clear or blurry given environmental conditions. I can also say that the smallest usable aperture always returns the best groups. I wish the GG&G ranging sight had different apertures and intend to approach them about that possibility.
Thank you everyone. I will see what I can do. Next time I go out I will change my stance according to where the sun is to see how much of it is atmospheric, and I may try using white out on the post to see if this helps.
Again thank you for your thoughts. They eye doctor is a last resort, but one I am considering.
Dude, all of that is unnecessary.
The intent of the 0-2 aperture is to rapidly acquire acceptable flash sight picture to put bullets through somebody’s chest as fast as you can. It will take so much effort and concentration to eek any repeatable precision out of it that it eliminates the very purpose of the sight. If you want/need to shoot 6" groups at 300, use the small aperture, if you are moving through an enclosure with a light, use the 0-2. It don’t need to be great, it just needs to be there.