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Eye Master
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Discussion Starter · #1 ·
Gus, and anyone else who has ever put a dial indicator on a rear sight, please chime in here:

I have a design in mind for an improved rear aperture ... actually two designs, well multiple designs, and I have not figured out how to combine them, but here are my thoughts:

If I take a normal aperture and use an EDM wire to cut the rack gear lengthwise through the middle of the gear teeth, plus cut a small opening for a spring that loads the parts front/back, upon re-assembly the spring will push the two halves of the gear rack out of alignment. So if I compress the spring to align the teeth, then feed it into the sight base so the pinion teeth get pinched between the two rack halves, this will effectively remove elevation lash.

Alternatively, if I somehow put in a sideways spring, it would take up side to side lash.

Question is if I can come up with a design that does both.

In the meantime, assuming I can fix either elevation or windage lash in the aperture, but not yet both ... which is a bigger gain?

Art
 

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I'm confident you have the skills to do it. It's borderline micro-machine work, but so was the adjustable trigger. Hunch tells me you'd want to do a whole new precision-threaded sight base, too. Other issues like unlevel or wavy rear sight receiver platforms you can't do anything about directly.
 

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MGySgt USMC (ret)
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Art,

The rear sight cover pretty much takes care of the elevation slop from spring tension, when the cover is fitted correctly. The problem is a whole lot of people don't know how to do that or they don't keep enough covers to use the right one for the RS they are working on.

Because the "slide" of the aperture has to move so far up and down, it is impossible to get all the slop out of it side to side. When we anneal the base, squeeze or peen it and lap the slide in - we attempt to keep that slop no more than .001" over the entire area the slide moves up and down. You have to have that much "slop" or the thing won't move without binding.

Now WHEN you fit the slide to the RS base that way, if you don't have a properly fitting RS cover, the slide can twist "catty cornered" in the RS base groove because there usually is some slop up and down when the spring tension is not right.

I have not even started to address the problems in many commerical receivers where one has to make adjustments to the receiver and/or the RS base and slide to get everything to work correctly.

Not sure if this helps.
 

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Eye Master
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Discussion Starter · #4 ·
Gus,

For elevation, I actually should have said 'lash'. Any gap between the teeth of the pinion gear, and the teeth of the rack will manifest itself as lash, even if the spring cover is tight. If you go up a notch or two, then down one, the down movement will not be one full click down, but is 1 click minus the gear lash. I think I can put a spring bias to eliminate that, and / or a sideways spring (maybe a detent) that would always load the sight to one side of the sight base.

I'll play CAD and see if I can post some pictures.

Art
 

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I hope this is not to far of this topic, but as Gus describes the difficulties with setting up the rear sight properly, is this a good reason to use a plastic sight cover? Or are they not needed to 'protect' the rear sight assembly if it has been set up right.

John
 

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Art,

Here is my input:

1. Design one where the sight cover is just an artifact and not controlling a lot of things like Gus articulated.
2. Design the elevation system that is repeatable with no lash where 1 click up, or down, or back and forth gives consistent and repeatable movement
3. Design the thread sytem for the windage that is repeatable and no lash where 1 click L, 1 click R, and back and forth gives consistent and repeatable movement.
4. Half minute click for elevation and windage is fine, a 1/4 is icing. Most peole can't effectively utilize the 1/4 minute.
5. Must retain the hood for the seniors shooters who use lenses in their hoods.

In the interim, here is how I did my rear sights:

To eliminage the slop in the rack and base, I have no way to anneal the base and besides I would not know what or how to do the fitting like the armorers do. So, I JB epoxy bedded the rack to the base, obvioulsy release is on the base and the areas I do not need epoxy on the rack like the area where the sight cover provides the down pressure. During curing I needed the rack to be pulled down hard against the base and steady. From an old speaker I lifted the strong magnet and let the epoxy cured while the base was sitting on top of the magnet and rack is in place.

The finished product is slop free from the bottom travel of the aperture to the top.

For the windage I used a ball and detent using those commercial windage knobs with 8 detents, but the slop in the sight base and the windage knob still did not give me a repeatable clicks, the 1-2 click L-R were the killers. Other people can favor within the X or 10 ring, this old boy just does not have that in him. I can't favor, I have to click.

For the windage fix, I sent a GI standard rear sight base and the windage knob to Gary at Pheonix Precision for modification. He reamed the thread and bushed the base, chased the threads on the windage knob. He then cut the threads in the base to match the windage knobs precisely. He milled off the 4 detents on the windage knob and cut 8 precision equidistant detents.

As Gus mentioned about the sight covers, I still have to pick the right sight cover to achieve the smooth movement, but the mods I did gave me good enough RS that I have the confidence in my clicks.

Now, put your R&D hat on again and retreat in your man cave and design us the best rear sight other than the pre-WWII basic design.
 

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Eye Master
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Discussion Starter · #7 · (Edited)
Well, what I was offering was only a small step. I was going to put spring loaded detent balls in the rack of the aperture, so at least the aperture is always biased down and to one side in the sight base.

Looks like I need to buy an extra rear sight assembly and maybe a rear half of an M14 receiver to experiment. Nez, I'll trade you a rectangular aperture for any scrap rear sight parts you want to get rid of ... :)

Art
 

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Well, what I was offering was only a small step. I was going to put spring loaded detent balls in the rack of the aperture, so at least the aperture is always biased down and to one side in the sight base.

Looks like I need to buy an extra rear sight assembly and maybe a rear half of an M14 receiver to experiment. Nez, I'll trade you a rectangular aperture for any scrap rear sight parts you want to get rid of ... :)

Art
Please continue with the detent ball in the rack, sounds like a good one.

I got some parts to send you.

Getting a de-milled rear half of a receiver should be a good addition to your tool box
 

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MGySgt USMC (ret)
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I hope this is not to far of this topic, but as Gus describes the difficulties with setting up the rear sight properly, is this a good reason to use a plastic sight cover? Or are they not needed to 'protect' the rear sight assembly if it has been set up right.

John
If one uses a hooded NM aperture, I most strongly recommend using one of the plastic rear sight covers to protect the hood.

ALSO and this is highly important that some folks do not think about. When you get done shooting with a Hooded aperture, RUN the elevation pinion all the way back down while counting your clicks. Then LEAVE it down until the next time you shoot. If you leave the Hooded aperture up and turn the rifle upside down on a bench, you can snap the hood right off the aperture.
 

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I think the rear sight of M1 and M14 rifles can possibly be improved. That said, I'm not convinced that it is necessary. This has proven to be the best sight ever put on a service rifle. It's even better than the sight presently found on the M16.

I realize that US service rifle sights are subject to wear and can develope slop over time. Back lash is controled by both the sight cover and internal springs in the elevation pinion assembly. Side play of the aperture can be limited by adjustment. Concern over this issue should be limited to the sights found on NM rifles since a much higher degree of accuracy is required. These sights are almost always hand fitted for minimum tolerances. As Gus pointed out, sight cover pressure is an important factor in insuring close tooth engagement between the pinion and aperture. Too much pressure can result in binding which may prevent the sight from acheiving consistant windage adjustments, even to the point of the windage knob unscrewing itself on left adjustment. Too loose and the gear teeth won't mesh resulting in elevation slop.

Like anything else, the sight is subject to improper fitting and wear, but works great when done right.
 

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Once again Gus Fisher has shared his unending knowledge of our rifle. Thanks Gus!
 
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