Iron sight eye relief

[divil]

When I first started shooting with irons, it was with AR-15s. I got into the nose-to-charging handle habit, because it was an easy way to be consistent, and it worked, in the sense that I got the best groups that way.

But recently I started experimenting more with ARs and my M1 Garand. And I found that now that I've shot a bit more, I get much better results with more eye relief. I think it's because with my eye up close to the aperture, I can't really see the aperture very well, so I'm relying 100% on consistent eye position to shoot consistently. But with my eye further back, I can see when the tip of the post is in the center, so I can do a more deliberate, geometric sight alignment each time. In other words I'm using the aperture in much the same way as the notch on an open rear sight.

If I go back too far, my groups seem to open up again. But I haven't tried this consistently enough yet.

Any iron sight target shooters have tips on the best eye relief, and how to maintain consistentcy? I've started putting blue masking tape on the stock to help me get a consistent position.

[zukiphile]

I wonder what would happen if you were to use a smaller aperture.

A small aperture can suppress alignment error and will work with a very slight distance between the eye and aperture. The point of perspective is fixed despite movement of the viewer's eye.

Now, if we move our eye from side to side a little bit, our first thought
is that the point of perspective would change. But since the point of
perspective is at the center of the sight aperture, and that is fixed, the
point of perspective does not move.

http://dougkerr.net/Pumpkin/articles/Aperture_Sight.pdf at p.6.

[divil]

I've seen that article linked and quoted everywhere on the web. It seems every discussion about how to use iron sights comes back to it. But it just doesn't make any sense to me.

Today at the range I set up my AR-15 on a rest with the small aperture (0.070") and lined it up with the target. By moving my head around without touching the rifle, I got completely different sight pictures. The target would move way off to the left or right of the post depending on where I put my head. Same issue up and down.

Doesn't this prove that alignment is critical? And how could it be otherwise? I did some calculations (well, ok I used the computer) and by my estimation, a misalignment of 0.010" with a 20" sight radius would produce a 1.7MOA error. That's just 1/7th of the diameter of the aperture, so it's not too hard to be off by that amount, especially vertically.

It sounds to me like the guys who wrote that article have found a fancy way to say "if you misalign your sights by enough to be off target by a lot, then you won't see the front sight through the aperture any longer, because it isn't there any more". In other words they are framing a simple statement about geometry as so much optical mumbo-jumbo.

But what I have found is that I can indeed still see the front sight roughly in the middle even after moving my head enough to put the target way off. If I had then moved the rifle to put the sights back on the target, it wouldn't have been aiming at the same place any more.

In any case I'm still struggling to get consistent results with any aperture sighted rifle. Every time I go to the range with any rifle I get one good group, and the rest are all over the place. Today I shot a 0.8" group and 50 yards with that AR-15, but most of the others I shot were more than twice that size. Same thing last time I went.


So what's the truth? How do people shoot well with aperture sights?

[Plainsman]

Consider all the National Matches shot with aperture sights on military rifles and how well the top shooters do…

I use Williams peep sights on lever actions and a 10/22 and do well with them.
I have two ARs and get good groups, but tend to “pull” left…

After writing that, Im wondering if Im torquing with my trigger hand with the ARs.

I too, like to have my nose at the charging handle for consistency with the ARs. Off the top of my head, Icant think of what I do for consistency with the levers, but Id guess my nose has something to do with it there too!

This thread and writing out my reply has me thinking now!

Thanks!

[44 AMP]

By moving my head around without touching the rifle, I got completely different sight pictures

Of course you did!!

Did you expect something different??? IF so, why?

Sights can only be aligned properly for one combination at a time. Move your eye to a different angle and they are no longer aligned properly.

Accuracy is repeatability. Doing the same thing, the same way, every time.

The first and most important part of the process is you, the shooter, being consistent. Do that well, the rest gets easier.

[ballardw]

"Spot weld" : consistent placing of the cheek in contact with the rifle for consistent sight picture and accuracy is one of the basics.

Where that spot is you should determine.

[David Todd]

I have never shot an AR, but have been shooting iron sighted match rifles since the mid 60's.
I still find myself checking my natural alignment, and am surprised at times how things move when it comes to stuff like cheek weld and head position- and this has become very evident since my latest shooting lens experiments!
Consistency in head positioning is certainly key. I have also found tht some shooters like less aperture opening than others, one just has to do some experimenting to find out what size is best. I used to shoot a wide open rear aperture, but have since closed it down to half, again because of the lenses I am using in my glasses.
David

[divil]

Of course you did!!

Did you expect something different??? IF so, why?

No, I didn't, but the article linked above said that I should.

[44 AMP]

No, I didn't, but the article linked above said that I should.

Yep, that's the Internet for ya!

[divil]

I have never shot an AR, but have been shooting iron sighted match rifles since the mid 60's.
I still find myself checking my natural alignment, and am surprised at times how things move when it comes to stuff like cheek weld and head position- and this has become very evident since my latest shooting lens experiments!
Consistency in head positioning is certainly key. I have also found tht some shooters like less aperture opening than others, one just has to do some experimenting to find out what size is best. I used to shoot a wide open rear aperture, but have since closed it down to half, again because of the lenses I am using in my glasses.
David

I hear this a lot but I don't understand it. Obviously you need to put your head in a place where you can look through the aperture and see the front sight, and maneuver the front sight into the center. But it's the alignment of the sights that matters, and it seems to be that there should be different head positions that allow you to center the sights.

I think maybe that the reason that head position matters so much is because the shooter is not really centering the front sight in the aperture. Instead, their head position causes them to misjudge where the center really is. (For instance, tilting the head down can flatten the bottom of the aperture as I mentioned in my other recent thread). This misjudgement is consistent as long as the head position is consistent, which is why people say that a rifle zeroed for one person is not necessarily zeroed for someone else.

[tangolima]

I think I know what your issue is. The peep hole should show up as a circle and the tip of the front sight is to be placed in the middle of that circle. The eye's pupil should be reasonably coaxial to the rear sight's peep hole for this to happen, and that's the part being done subconsciously/automatically with practice.

With a hard cheek weld, the peep sight peep hole may appear to have a flatten bottom. It is because the low eyelid gets pushed up and starts to obscure the lower part of the pupil. But the most part of the circle is still intact and the center of the circle can still be located. The front sight tip must be placed at the center of circle, not the center of the image appears. In order not to have the flattened rear sight image, try having your head a bit upright when welding your cheek on to the stock.

Zeroing is particular to shooter is not only because of that. The rifle moves between primer ignition and bullet clears the muzzle. This part of movement is different from shooter to shooter.

-TL

Sent from my SM-N960U using Tapatalk

[44 AMP]

I hear this a lot but I don't understand it. Obviously you need to put your head in a place where you can look through the aperture and see the front sight, and maneuver the front sight into the center. But it's the alignment of the sights that matters, and it seems to be that there should be different head positions that allow you to center the sights.

There are different head positions that allow you to center the sights. EVERY SINGLE ONE that allows you to look through the sights and see your target.

Not sure what part you don't understand. Using iron sights requires aligning 4 things. YOU (your eye - head postion) the rear sight, the front sight, and your target. All these things need to be aligned in a straight line , and with each other in the process.

You can adjust to "center" or "line up" your sights with each other and your eye and the target in about any position you put your head. But, this alignment only works for that one head position.

Move your head to a different position, and the alignment is now "off" and has to be redone, in order to put you back on target.

Each time you change something involving how you look at and through your sights, it can result in your previous alignment now being off target.

Sights can be adjusted for almost anything, but only for one specific set of factors at a time. Just as your sights can only be "perfectly zeroed" for one weight and speed of bullet at ONE range. Change any of those factors and your sights are now "off".

Perfect on target at 25yds, cool. Same exact everything at 100yds, not so much, you need to make an adjustment to be back on, due to the change of bullet trajectory. In this case the change was the target range.

What part of that don't you get?
(not trying to be rude, trying to understand, so we can help)

[divil]

There are different head positions that allow you to center the sights. EVERY SINGLE ONE that allows you to look through the sights and see your target.

Not sure what part you don't understand. Using iron sights requires aligning 4 things. YOU (your eye - head postion) the rear sight, the front sight, and your target. All these things need to be aligned in a straight line , and with each other in the process.

You can adjust to "center" or "line up" your sights with each other and your eye and the target in about any position you put your head. But, this alignment only works for that one head position.

Move your head to a different position, and the alignment is now "off" and has to be redone, in order to put you back on target.

Each time you change something involving how you look at and through your sights, it can result in your previous alignment now being off target.

Sights can be adjusted for almost anything, but only for one specific set of factors at a time. Just as your sights can only be "perfectly zeroed" for one weight and speed of bullet at ONE range. Change any of those factors and your sights are now "off".

Perfect on target at 25yds, cool. Same exact everything at 100yds, not so much, you need to make an adjustment to be back on, due to the change of bullet trajectory. In this case the change was the target range.

What part of that don't you get?
(not trying to be rude, trying to understand, so we can help)

I don't know if I can explain it any better than I have, but I'll try: the part I don't get is why everyone says that a consistent head position is fundamental to shooting accurately.

If you put the rifle down and pick it back up again, then (with most ordinary rifles) your head is more or less guaranteed to be in a different position than last time unless you work very hard to make it consistent. What I'm saying is, I don't see why that should matter (unless you're in a hurry I suppose, which is a thing for some people). You've just picked up the rifle so you have to align your sights anyway, even if your head position is extremely close to where it was the last time.

Yet there seems to be universal agreement out there that consistent head positioning is essential.

In the second paragraph of my last post, I was just speculating as follows: the idea that consistent head position is essential does start to make sense if you combine it with the oft-quoted internet advice that you shouldn't pay any attention to sight alignment. Because if you're going to shoot with misaligned sights then yes you better be misaligning them the same way every time.

[tangolima]

Target, front sight, rear sight; all three need to on a straight line. The eye is there to make sure of that. If the eye detects misalignment, the shooter makes corrections. Consistent head position makes the above process go faster. That's about it.

-TL

Sent from my SM-N960U using Tapatalk

[44 AMP]

the oft-quoted internet advice that you shouldn't pay any attention to sight alignment.

This kind of "advice" is, to me, on the level of "its a shotgun, you don't need to aim, you can't miss" kind of thing.

It's NOT TRUE.

Some of it is PARTLY true, in certain specific situations, but as overall general advice, it is barking STUPID.

the part I don't get is why everyone says that a consistent head position is fundamental to shooting accurately.

First thing is, we're talking about target shooting here, right??? Winning matches (or just shooting small groups) is about consistency, both the mechanical precision of the arm and its ammo, AND its about the shooter's consistency.

What may be valid advice in a combat situation, where shooting (getting the shot off) fast enough aimed well enough to hit somewhere on the target (enemy) can be vital to your survival. Maximum precision isn't required, only the shot being "good enough" to save your butt.

Target shooting is DIFFERENT. You have the time you need to get precise. To get into that one position you've sighted in with, to adjust yourself to make getting into that position as reliably repeatable as humanly possible.

IF you don't do that, then despite you lining up the sights, all the things you line up (you, the sights, the target) DO get lined up, BUT they are lined up slightly differently than the last time and so the bullet will go somewhere slightly different than it did the last time, and that is what opens up your groups and spoils accuracy.

The reason we all say CONSISTENT head position is vital is because if you aren't consistent, neither will your bullet impacts be. If your head isn't in (as close as you can make it) the same position, even though you are lining up the sights, each shot is literally sighting in the rifle all over again for the (new) position your head is in when you fire.

Does this explanation make sense to you?

[divil]

Yes I'm talking about precision target shooting, where time is not a factor. But I don't get this:

BUT they are lined up slightly differently than the last time and so the bullet will go somewhere slightly different than it did the last time, and that is what opens up your groups and spoils accuracy.

I don't see why this should make the bullet go somewhere different. If you line up the sights, then move your head without moving the rifle, the sights won't look lined up any more. If you now keep your head where it is, and fix the sight issue by re-aligning them, are you not aiming at exactly the same point as before?

What you are saying implies that having your head in a different position will cause the sights to appear to be lined up the same way they were before, when they're actually not.

[Scorch]

Aperture sights are a very simple tool, but if you use them other than the way they were designed to be used you will get strange results. Put your cheek on the stock in EXACTLY the same place every time. Get EXACTLY the same sight picture each and every time. Breathe EXACTLY the same each time. Squeeze the trigger EXACTLY the same way every time. And you will get very consistent results. There are still record groups fired 100 years ago using peep sights on the books from what I've been told.

I talk with a lot of people who are having difficulty shooting. They always think it's the rifle, when I ask most tell me they are very good shooters. When I bring them the targets I shot using their rifle, they seem to think I shot the groups at 50 yds or closer. And I'm not a great shot! Most rifles shoot better than the shooters. Quit messing around and learn how to shoot.

[zukiphile]

Originally Posted by divil

I've seen that article linked and quoted everywhere on the web. It seems every discussion about how to use iron sights comes back to it. But it just doesn't make any sense to me.

Today at the range I set up my AR-15 on a rest with the small aperture (0.070") and lined it up with the target. By moving my head around without touching the rifle, I got completely different sight pictures. The target would move way off to the left or right of the post depending on where I put my head. Same issue up and down.

Doesn't this prove that alignment is critical?

Yes, alignment of the sights is critical. That doesn't mean that alignment with the center of the pupil is critical. Where the image projected is smaller than the pupil, the eye position can shift somewhat without a change in the image.

A smaller aperture produces a smaller image than the eye's "aperture" and acts as a lense. This masks some of the shooter's alignment error.

I've performed that same test with a small aperture and observed that the image of post and target remain constant. With a large aperture, I get the result you describe.

[divil]

I've performed that same test with a small aperture and observed that the image of post and target remain constant. With a large aperture, I get the result you describe.

How small are we talking here?

[Jim Watson]

When I was shooting BPCR the idea was to get the Soule vernier tang sight as close as possible without the sight poking you in the eye from recoil. The Hadley eyepiece to be set for the smallest aperture the lighting and your eyesight allowed.

The front sight was a globe, usually with an aperture insert that gave you concentric circles all the way - bullseye, insert, globe, peep. It worked well enough for irregular metallic silhouettes although some shooters use a post. There was an outfit selling inserts the shape of the targets but that meant you would have to change inserts every time you changed targets.

[zukiphile]

Originally Posted by divil

How small are we talking here?

Nothing special. Just an A2, so probably a .065" to .070".

[divil]

Nothing special. Just an A2, so probably a .065" to .070".

Then you got a very different result from the one I got with the same sized aperture.

[darkgael]

I shot my all time best five shot group years ago…one inch at 100 yards…..using the little aperture on the ladder sight on my 1903 Springfield. That tiny hole is nearly a foot from the shooter’s eye when used.

[divil]

After experimenting a bit I can see the parallax reduction effect that the article talks about using a magpul AR-15 rear sight I had lying around. It's more noticeable if you compare the amount of parallax with and without the aperture, all else being equal. It's very impressive but it still doesn't seem to work for with with the actual rifle pointing at a reasonably distant target.

I think there are a few reasons:

* I noticed that the effect is far more pronounced with a shorter sight radius, and unsurprisingly, with a closer target.

* I suspect that the numbers they picked for the example in the paper are a little exaggerated. They use a 1mm aperture and a 4.2mm camera to simulate the human pupil. But 1mm is close to the smallest aperture you ever see on target sights. AR-15s have 1.8mm apertures, Tech Sights come with a 1.5mm as standard. And 4.2 seems to be towards the bigger extreme for a human pupil in good light .

I happen to have one of those cardboard scales used for measuring interpupilary distance (it came with my glasses). I held it up to my eyes and took a selfie, then zoomed in and measured out 4mm on the photo of the scale with my caliper. The width of the caliper jaws was then easily twice the diameter of the pupil in the photo. Now the scale was a few mm in front of my pupil so it's far from a perfect measurement, but I am confident that 4.2mm is an unrealistic estimate for moderate indoor light, and probably a worse one for good outdoor light. It seems to me that with a typical 1.8mm aperture and good light, the aperture and pupil could be very close to being the same size at least for my eyes.

Of course I already knew from experience that sight alignment matters for me with this rifle, but it's good to be able to reconcile my experience with the theory in the paper. I'm interested to see how things work out with smaller apertures as zukiphile suggested.