Putting it all together (Part 2)

So you have the results calculated in Part 1, what now?


1- Range correction

You know what range you want to shoot at, 680 yards. Now take out your ballistics table. This data is not for any existing bullet. I made it up for illustration purposes!

Range (yards) 100 200 300 400 500 600 700 800 900 1000
Drop (inches) 4.1 5.2 0 -12.5 -30.2 -60.5 -105 -164 -240 -308

The drop at 600 yards is -60.5. Add to that 8/10 of the difference between drop at 600 and drop at 700.

8/10 * ( -105" -  -60.5" ) = -35.6" AND -60.5" + -35.6" = -96.1" of drop

My scope as 1/4 MOA clicks. So to know how many clicks to apply, I must know how many MOA 96" is at 680 yards.

1 MOA as 680 yards is 6.8". Therefore:

96" / 6.8" = 14.12 MOA

4 clicks per MOA, so:

14.12 MOA * 4 = 56.48 clicks

So I will rotate my elevation turret 56 clicks up. Half a click is not possible (!).

Note: 8/10 of the difference between drop at 600 and drop at 700 was used to estimate the bullet drop at 680 yards. This is a quick estimation technique. The real value requires much more complicated calculations, but this method gives close enough values.


Wind correction

Again, some fictitious wind drift data, for a 5 mph wind:

Range (yards) 100 200 300 400 500 600 700 800 900 1000
Drift (inches) 0.3 0.9 2.3 4.3 6.9 10.1 14.7 20 26.3 33.6

Wind drift is proportional. The wind here is 9.64 mph. And my table is for 5 mph. 9.64 mph / 5 mph is 1.9. Therefore I can calculate the drift value based on the table, and multiply it by 1.9.

Wind drift at 680 yards for a 5 MPH wind is:

10.1" + 8/10 * (14.7" - 10.1") = 13.78"

Multiplied by 1.9:

13.78" * 1.9 = 26.2"

Convert to MOA, at 680 yards:

26.2" / 6.8" = 3.85 MOA

Convert to clicks (remember, 4 per MOA):

3.85 MOA * 4 = 15.4 clicks

So I will turn my windate turret by 15 clicks (.4 clicks is not possible!) left.


Final results

Range correction: 56 clicks up

Windage correction: 15 clicks left

Lead: 2.55 mils


Lead aim point

Send it when the target center is at the 2.55 mils point in the scope.

The target moves from the right to the left. When it reaches the 2.55 mils point, send it.