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Discussion Starter #1
I recently read some repair manuals for the Mosins and found out that the rear sight leaf is adjusted using a calibration tool called K-17. Only after the rear sight is calibrated the front post is installed. This would be the best way to sight in a real sniper (IMHO) :)

Does anyone own one or has drawings/blueprints for it? If you do own it, could you possibly provide some measurements?

Only three measurements are needed to adjust the sight properly: The height of the calibration tool above the axes of the rear leaf around which the rear leaf rotates. (for aim 3, 6 and 8).

If anyone is interested I could provide mathematical calculations of what the heights should be.
Unfortunately, pure theoretical calculations have a degree of precision dependent on the accuracy of the tools used for measurements, practical field data, etc...
So if you have one, would you give us the ultimate word on it.
 

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But what is there to adjust? Are you saying that that is why some of the slider blocks on the rear sights appear to be ground on the bottom and others are square?
 

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Discussion Starter #3
Yes

Exactly what i am saying :) This practice is described in the repair manual for this rifle and the shooting manual. Both manuals published by USSR in the 40s and 50s.

With respect...
 

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So what are the mathematical calculations?
 

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Discussion Starter #5 (Edited)
Calculations

Here we go.

I wrote out the stuff in Russian but I will explain. If you look at the drawing of the rifle you will see that the axes of the rear sight leaf is on the same plane with the base of the front post. This makes the calculation a bit "simpler". The leaf moves in an arc around the axes changing the distance to the front post. This is why the axes of the rear leaf was chosen as a constant value.

Look at the geometric setup of the problem on the second image:
1. (L) is the distance from the front post to the axes of the rear leaf. (540 mm by the book)
2. (alpha) is the angle at which the rifle is held with respect to the line of aim.
3. (m) is the height of the front post, which for an 91m/30 sighted with the bayonet on must be 11.55 mm.
4. (R) is the length of the rear leaf from the axes to the tip (82mm).
5. (x) is not important because it is only used to equate to equations.

Now, just follow the equations and you get the the height (h). The correct (h) is the larger one. You add the height of the front post to the value you calculate. This gives you the correct height of the leaf above its axes.

Now, the question is how to get the tan (a). This is really the ratio of the average height of the impact point on a 50 or 100 m target when shooting with the sight set at 3, 6 or 8. So for 3, the table says the impact point is 10 cm above the point of aim. The ration would be
10 cm/5000 cm(50m) or 0.002. For 6 it would be 50/10000=0.005 and for 8 that would be 90/10000=0.009.

3: 12.7 mm
6: 14.6 mm
8: 21.9 mm
 

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Calibration tool k-17

As Vinny Barbarino used to say, "I'm SO :confused:"....
 

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It appears that my algebra and trigonometry has gathered more rust than my oldest Mosin! But!! I measured my front sight post height and it was at 11.5mm above the sight base. Close enough!.. and it saves me from all that thinking!!
 

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Calibration tool k-17

Most of the rest of us too; I imagine....;)
 

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Discussion Starter #11
This is the correct linement tool set?
Paul
Is this your tool, or it is an image from the web? If it is yours, would you be kind enough to possibly measure the three distances by sticking it into the barrel (hopefully after cleaning it :).
 
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