Lyman #2 Tang Sight

[MEHavey]

Does anyone know the thread pitch (tpi) for the Lyman #2 Tang sight stem ?
(for running calculations of MOA/turn when sight radius known)
I'm assuming 28 tpi for now, but haven't been able to Google real references.

Thanks in advance.....

 

[Lefty38-55]

FWIW on the Buffalo Arms website, their listing for the Lyman #2 sights says "Features include height index marks on the aperture post and an .800" maximum elevation adjustment. Also included is a .093" x 1/2" quick sighting aperture and .040"x5/8" target disk. Offers precise elevation adjustments to 1/10 of a minute, (.001")".

But remember ... how much it will move the impact for YOU depends on the spacing between the front and rear sight. Rear sights with fixed front sights are on 2 different planes, whereas a scope and the target are on the same plane, which is why a scope can be marked for adjustments such as "1/4" clicks at 100-yards". Not so with iron sights.

Example ... Let's look at 2 rifles, one with 24" between the tang aperture and rear of the front sight blade (the 'sight radius', NOT the barrel length!) and the other with 28" sight radius. Raising the stem 0.100" on the rear sight moves the bullet impact UP 15" on the shorter sight radius barrel and 12.85" on the longer sight radius.

Tip - If you are shooting 100-yards and are 1.2" low, use this formula to determine 'how much' to raise or lower the rear aperture post, of which we'll call it 'X', or the unknown. First, measure your sight radius, that is 'SR', in inches. Distance of 100-yards = 3600 inches. For this example let's assume you have a 20" sight radius or 'SR'.

The formula is 'constant relationship', where X (unknown) divided by the SR (or 20" in this example) is equal to 1.2" (the amount you're off @ 100Y) divided by 3600" (100-yards valued in inches). This formula is expressed as X/20" = 1.2"/3600. Cross multiply top one side to bottom other side, for both sides, giving 3600X = (20 x 1.2), or 3600X = 24. Solve for 'X', where 24/3600 = 0.0066". The result is that the rear aperture post needs to be raised almost 7-thousands of an inch to move the bullet impact up 1.2" at 100-yards.

I am presuming by what Buffalo Arms had posted, that you would need to raise it by counting almost 7 of the little index marks that they have around the sight post stem. Capice?

 

[MEHavey]

"....height index marks on the aperture post...precise elevation adjustments to 1/10 of a minute...." (so says Buff Arms and host of "other" references)

Uuuuuuhh..... somebody's gotta point out those "index marks" on the Lyman#2,
(`cause I haven't ever seen any of any version for sale over the last 25 years. )
(and 1/10 MOA is in someone's dreams)

That said, 28 tpi is just fine for useful calculation/field use.

 

[halfmoonclip]

For the OP, do you want to be able to adjust in the field for different distances?
My Marbles has markings on the elevation wheel, but I'm not sure exactly what they signify. As others have noted, actual POI changes will depend on barrel length.
If all you want to do is zero the gun, simply fiddle with adjustments as deadreckoning until it hits where it looks.
Moon