III. A Brief Introduction to the Use of Telescopic Sights riflescope

Update time : 2025-05-15 16:29:50

III. A Brief Introduction to the Use of Telescopic Sights riflescope

Lens Covers

Lens covers are essentially used to protect the lenses when the scope is not in use, preventing scratches and dirt. There are various types of lens covers, including some that resemble camera apertures, among others.

Diopter Adjustment

The diopter adjustment typically ranges from +2 to -3. Since shooters have varying ages and visual acuities—some have normal vision, while others may be nearsighted, farsighted, or have astigmatism—the diopter adjustment ring on the eyepiece assembly can modify the optical path to match the user's vision as closely as possible. The diopter adjustment is located at the end of the eyepiece.

Mil-Dot Ranging: A General Method for Simple Ranging

The formula for calculating distance using mil-dots is: (Target Height x 1000) / Mil-Dot Reading = Distance.

Note that the unit of measurement for the target height (the approximate size of the target should be memorized in advance) will be the same as the unit for the calculated distance. If unit conversion is necessary (assuming target measurements are in inches):

Target Length (in inches) x 25.4 / Mil-Dot Reading = Distance (in meters)
Target Length (in inches) x 27.77 / Mil-Dot Reading = Distance (in yards)

For example, if a person is 1.75 meters (68.9 inches) tall and appears to be 4 mil-dots high, the distance would be:

1.75 x 1000 / 4 = 437.5 meters

or

68.9 x 25.4 / 4 = 437.515 meters

or

68.9 x 27.77 / 4 = 478.34 yards = 437.39 meters.

Do you remember the distance estimation method used by Li Yulong in "Bright Sword"? By stretching out your arm, observing the position of your thumb with both eyes, and then closing one eye to see the shift in the thumb's position, the distance to the target can be estimated by multiplying the shifted distance by 10.

Distance = Target Height x 900 / Mil-Dot Number.

What else are mil-dots used for? Isn't measuring the target's height with the vertical mil-lines on the crosshair sufficient for ranging? Why are there also horizontal mil-lines?

For example, consider shooting a moving target. Suppose the bullet travels for 0.4 seconds at a distance of 500 meters, and the target is a running adult male with a speed of 3 meters per second. To hit this target at 500 meters, a lead of 3 m/s x 0.4 s = 1.2 meters is required. The calculation formula is: (Lead x 1000) ÷ Target Distance, i.e., (1.2 m x 1000) ÷ 500 = 2.4. In this case, adjust the scope to the 500-meter zero and aim at the 2.4-mil position between the 2nd and 3rd mil-lines. The bullet will hit the running person at 500 meters with a speed of 3 meters per second.

Minute of Angle (MOA)

After attaching a scope to a firearm, it usually needs to be zeroed in. Zeroing means setting a fixed distance for the accuracy calibration of the gun and scope (essentially aligning the center of the scope's reticle with the point of impact at a commonly used shooting distance).

Precision Adjustment: MOA is the unit for the click value of the adjustment screws. The two knobs in the middle of the scope are for precision adjustment. The one marked "Up" adjusts the vertical direction, academically known as "elevation adjustment." The other one marked "R" adjusts the horizontal direction, known as "windage adjustment."

To briefly explain the MOA unit: it is an angular unit. For example, as shown in the figure below, an angle ∠ extends outward. Remember that one unit of MOA is equivalent to:

inch at 100 yards
inches at 200 yards
inches at 500 yards
8 inches at 80 yards

Two units of MOA would be:
inches at 100 yards
inches at 500 yards
6 inches at 80 yards

A bullet does not travel in a straight line after being fired; it follows a parabolic trajectory, similar to a dolphin leaping out of the water. The water surface can be considered the aiming baseline. The bullet first breaks the surface at the first zero point, follows an elegant arc, and then pierces the surface again at the second zero point!

——Continued Analysis of Telescopic rifle scope Sights,by JAXY binoculars

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III. A Brief Introduction to the Use of Telescopic Sights riflescope