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!