A receiver sight trivia Question

[Chill Wills]

Lyman receiver sight calibrations: A trivia Question.

LYMAN Receiver Sight No. 57 & 66

Please read this all as I understand how to use and accurately move the sight.

My question is what is the bases of the odd marking system? I am sure it will be an “ah-ha” when I learn what Lyman is/was thinking when so long ago they starting marking sights this way.

The Windage and Elevation knobs move the sight ¼ MOA @100yards. I have NO questions about this.

Here is my Question: On the side of the Receiver sight there is a scale.
What is the meaning of the 0, 15, 30, and 45 on the side of the receiver sight?
Below is what you see plus lines for 3, 6 9, 12 etc. that I cannot reproduce easily here.

-0
-15
-30
-45

Again, there are 5 division lines (unnamed) in between these major numbers. Each of these lines move the sight 4 MOA on the target at 100yards.

A detent button will allow sight movement up and down and come to rest in these 4MAO stops. Moving from 0 to 15 for example is 20 minutes. OK, but odd.
Until I learn what Lyman was thinking it would make more sense to me to have marked them

-0
-20
-40
-60
BUT I know they had something in mind……. :popcorn:

[Sturmcrow]

You know, 20 MOA is not too far off from 15 inches at 200 feet. Maybe that was the standard, back in the day.

It's also not too far off from 15 feet at 1000 yards, if one were zeroing in that far out.

20 MOA is also really close to 15cm at 500m, if metric floats your boat.

One thing that I did not consider when first throwing out ideas is that your value of "20 MOA" is entirely dependent upon the distance from rear sight to front sight. On a longer-barreled rifle, maybe the "15" mark actually would correlate to 15 MOA. Didn't some of the rifles back then have awfully long barrels, a la the 45-70 Handi Rifle Buffalo Classic with the 32" barrel.

[Doc Highwall]

They might be the number of revolutions on the knobs.

[Chill Wills]

[QUOTE=Sturmcrow; One thing that I did not consider when first throwing out ideas is that your value of "20 MOA" is entirely dependent upon the distance from rear sight to front sight. [/QUOTE]

Thanks for reminding me that I did not say that the value per Lyman is set for a 27-28 inch sight radius. This is about right for a rifle length Lever rifle barrel of 24 to 26 inches, which was common back in the early days when these first came out. Remember the receiver sight is a few inches back from the rear of the barrel making the longer sight radius of 26" or 28" ..... close enough for most of the adjustments we need to make.

[MtGun44]

AFAIK, they were just reference numbers. If you found that your gun shot one load to where
you wanted when set on 9 and another load or range at 15, then you just remembered it and
there you were. I don't think there was any grand plan that wrapped around a particular load,
unlike military rifles which have ONE load and the sights are specifically designed for that
gun, barrel length and ammo.

Bill

[W.R.Buchanan]

These sights were designed to reflect "Minutes of angle" This is more precise on Lyman 48's and sights that were used for target shooting but the overall concept is still the same. With the #48's on a Springfield rifle with a standard 24" barrel the movements are indeed 1/4MOA per click.

You zero the gun at 200 yards. and then you zero the elevation pointer and the elevation knob and set the set screw down stop. Then based on the known trajectory of the standard load you are using you can dial hold overs for 300 and 600 yards or further. IE National Match distances. "Exactly" following the sight is all contingent on knowing the correct velocity which in turn generates the exact trajectory whihc gives the holdovers at all distances from the gun.

All of this can be predicted by knowing the velocity and ballistic coefficient of the bullet and entering it into a ballsitic calculator (available on line, just google it) which will give you nearly exact buillet drop for any given distance. Which in turn you enter into your sight.

You can also simply sight the gun in at each distance and record the sight settings on your range card for future use (DOPE) nN that case the markings would all become reference numbers, but since the sight repeats it doesn't really matter, because what matters is that you can return to a previous holdover and hit the target. Even so the movements are still 1/4 MOA per click.

Also the movement of the elevation slide for the 300 and 600 distances would be done with the slide release and moving the slide up to the correct MOA holdover and then +/- several clicks to the exact MOA required to be dead on with whatever hold you normally use. IE 15 minutes plus 3 clicks would be 15.75 MOA This feature makes it so you don't have to count 63 clicks up to achieve 15.75 MOA. You can see the obvious potential for errors. Returning to mechanical zero is just a matter of zeroing the knob and then using the slide release to drop the slide to the setscrew stop. It will repeat everytime and not engage even if you are one click off zero with the knob.

The quality of the older Lyman 48's was enough that the sights would repeat very well and it is entirely possible to sight the gun in for a variety of loads just by recording the holdovers for the various loads while still using the basic 200 yard zero for your most used load. Which you can always return to as it's numbers are always zero and there is a stop set. You always return the gun to zero when done shooting for the day so you don't get lost, just like you do with a scope when dialing holdovers with the elevation dial.

The Lyman 66 is a levergun sight and it works the same basic way except the verticle MOA scale moves instead of the pointer You zero at 100 yards and then zero the movable scales on the elevation and windage slides and knobs. Then shoot at 150 and 200 yards and record the elevation settings for future use. Not much reason to go beyond 200 yards for any levergun but you still can just in case you need to shoot somebody at 300 yards with your .30-30. You never know?

The #57 series sights are essentially the same as the 66 series except with different bases for many bolt action, and other style rifles.

The 66 and 57 series sights have square ways for the elevation slide as opposed to dovetail ways of the Lyman 48 series sights. They are not inherantly as precise however they are plenty good for any levergun or hunting rifle.

The Lyman 48 series receiver sights were the gold standard of rifle sighting for 50-60 years. The new stuff is not that much more accurate and really the advances in Iron Sights are more about cosmetics and splitting hairs than actual practicality.

Learning how to run one of these sights is a worth while endevor for anyone who likes to shoot and actually trys to be good at it. They are a helluva a lot more accurate than most would think and there is alot to learn here and it is actually fun to gain the understanding, and all of it applys to any shooting you do.

One of the best places to get this knowledge is by going and shooting a National Match event near you. They are literally everywhere.

Randy