Post refraction in some rifle aperture sights?

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Ignition Override

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With my FR8 Mauser carbine, which has the standard HK sights, the front post looks much thicker when viewed towards a bright ceiling light bulb.
When sweating outside today with scattered or broken clouds barely blocking the sun, did not notice anything different.

Last week a friend had sliced off the original post on a spare sight, and replaced it with a taller roll pin, which has a uniform width.

Refraction also seems to be the case with the nice Service Grade Garand from the CMP: SA action and barrel, but at least the classic post is very thin.

It does Not seem to be the case with the short Enfield #5 nor the longer, standard #4s.
Are these perceptions because of different sizes/thicknesses of the aperture openings, or different color of paint or bluing?
 
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IO, I read it, but it's a bit above my pay grade. Maybe one of the real experts here will come along shortly to offer meaningful input.
 
IO, I am not entirely sure I get what you mean by refraction.

I can tell you the one rifle I have the most time on is my air rifle. I have shot it in more lighting conditions than any other rifle. Low light, bright light and only target lit. Also in rear sight in shade, front sight in bright and target in shade. The front post is nickel plated and I paint it flat black. (krylon camo) If I rub or scratch off some paint I don't get as near a good sight picture. Same for rear. but front is more prevalent. I used to be careful about masking off the sights, now I just spray and pray.

On other rifles (AR, Garand) I have notice any lint or dust will degrade the sight picture by having a fuzzy look. I have a gun case that would put some lint on the front sight. I find the rear aperture needs to be even cleaner. The Garand had some fine nicks on the edges. Cleaning up any burs helps. Rounded corners are hard for me to deal with. Having a sight face that is crisp seems to help me.

Any oil on the sight will not help. Being consistent with eye placement helps.

Then making sure to stay focused on the front sight is the final frontier. Sitting on a sight too long also leads to the sight pic going down hill.

I'm a low pay grade myself!!
 
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Ignition Override

I suspected that the topic would be ignored.
Oh well...back to the other websites.
Click to expand...

You waited four hours and didn't get an answer so you insult the people who might answer your question...............

Oh well........back to other postings that don't have built in time limits. :eek:

I was going to say things like visual acuity, depth of field, shape of the front sight and the angle of the sunlight hitting the front sight and maybe a long dissertation on why they invented hooded front sights but I just don't have time.

Oh well...........we will treat you like a Marine recruit.

maggot.gif

Many inexperienced Marines do not recognize that light conditions can affect shooting accuracy. A change in light condition can cause a Marine to aim at the incorrect aiming point. What appear to him as center mass on the target may in fact be several inches higher or lower, left or right. A shooter may need to adjust his rifle sights to compensate for the effects of changing light conditions. Regardless of how indistinct the target appears, maintaining a center mass hold ensures the best chances for an effective shot. Common light conditions include:

a. Bright Light. Bright light conditions exist under a clear blue sky with no fog or haze present to filter the sunlight.

1) Bright light can make a target appear smaller and farther away. As a result, it is easy to overestimate range.

2) Bright light shining from above makes the front sight post appear shorter and bright light from the side makes the front sight post appear narrower. This affects aiming because the Marine will aim at center mass using the perceived tip of the front sight post, which is altered due to the effects of light.

b. Haze. Haze exists when smog, fog, dust, smoke, or humidity is present. Haze is not bright, but it can be uncomfortable to the eyes. Haze can make a target appear indistinct, making it difficult to establish sight picture.

c. Overcast. Overcast conditions exist when a solid layer of clouds blocks the sun. The amount of light changes as the cloud cover thickens. Overcast conditions make a target appear larger and closer. As a result, it is easy to underestimate range.

1) Light Overcast. Light overcast conditions exist when no blue sky is visible and a thin layer of clouds is present. In light overcast, both the target and the rifle sights appear very distinct. Light overcast is comfortable on the eyes with no glare present, making probably the best light condition for shooting.

2) Dark Heavy Overcast. Dark heavy overcast conditions exist when the sky is completely overcast with most of the light blotted out by the clouds. As the overcast thickens, it becomes difficult to identify the target from the surroundings.

d. Scattered Clouds. Scattered cloud conditions exist when the clouds are broken up into small patches with the sun appearing at times between the clouds. A shooter’s eyes may have problems adjusting between a target that is brightly lit and one that is shadowed.

e. Moving Clouds. Moving clouds exist when scattered clouds move across the sky rapidly, making the sun appear periodically. Rapidly moving clouds can fatigue the eyes due to the rapid changes from bright light to shadows. This condition is probably the most difficult to contend with because the light changes rapidly. If the situation permits, this condition can be compensated by selecting one of the two light conditions (bright light or shadow) in which to fire. Best results are obtained, if each shot is fired under the same light condition.

f. Record Light Condition in the Data Book. A shooter should record a significant change in light condition in the REMARKS block of the data book. This information helps determine how the type of light condition or change in condition affects a shooter’s BZO.
 
I'm honestly not sure about what you mean by refracting the image of the front sight post, but the only advice I can give for what I think your problem may be is this:

I think blackening your sights with some soot couldn't hurt. The flatter and blacker the sight color is, the less reflective it is, and the better off you will be.

Also, the sight picture can change drastically with eye relief. Make sure to use the exact same cheek weld every time and ensure your eye is the same distance from the rear aperture for every shot. You might want to use some sort of "landmark" on the rifle to index yourself.

Other than that, I am at a loss. Sorry I couldn't be more helpful.

Jason
 
Back when I wore contact lenses, I would get a slightly taller ghost image of the front sight. I could see right thru it, and only used the hard image, and therefore didn't do the M-word.
jim
 
IO, I am not entirely sure I get what you mean by refraction.
Click to expand...
I'm honestly not sure about what you mean by refracting
Click to expand...
That's because he means diffraction. When light passes next to any edge, some of it "bends" or scatters. When it passes through a hole, it diffracts at the hole's edges, and the closer the edges are to the center (that is, the smaller the hole) the more the diffraction interferes with clarity.

Pinholes can interfere with clarity in other ways, too, but they can also increase depth of field and minimize the effects of the viewer's uncorrected refractive error.
 
Thanks for the info. Please pardon my impatience a while back, and (bigedp51) wasn't trying to insult.
This hobby came so late in life that I actually look up to all you guys, and your advice.

With one eye open, I aim at a room's ceiling light bulb. Viewing the front post from Outside a rear aperture, with the bulb behind it (about five feet away), it looks a good bit thinner than when simply viewed from any aperture.

Maybe the 'sight black' from my Gun Guru was not used on enough post sights?

bigedp51: I enjoyed your Marine style. Nice sense of humor.
Your first 2) might have really nailed it on the head, regarding bright light from the side.
 
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Yeah, looking at the lightbulb you are getting a lot of diffraction going around the post... if you dared using an even brighter bulb, or the sun, you will likely experience a total washout of any sight picture at all... Personally, I like using polarized safeties to reduce glare etc. Not a fix-all, just something I got addicted to :)
 
Almost any type of flame, even from a zippo will carbon up a front sight and take light glare away. Important to do so as your eye will tend to pull toward the light, changing your impact of the bullets on target. Carbide lamps are the greatest, but I haven't seen one in years!
 
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