Putting it all together (Part 1)


Everything at once! Calculate the elevation and windage corrections based on the following data:

Target size 76"
Target size 3 mils
Angle 15° down
Wind 5 mph, left to right
Distance covered by target in scope 5 mils, right to left
Time it took 1.5 seconds
Bullet muzzle speed 3250 fps
Bullet speed at the range you will calculate2100 fps
Shooter Not moving

1- Range


1.1- Horizontal range

(Target size in inches * 27.778) / Target size in mils = range (yards)
(76" * 27.778) / 3 mils = 703 yards

1.2- Correct range for angle

range * cos(angle) = horizontal range
703 yards * cos(15) = 680 yards

The data says: 15° down. What if it said 15° up? No difference! Refer back to the Angles page...

Scope elevation should be set for a range of 680 yards.


2- Moving target


2.1- Target speed

(Distance in mils * ( size of 1 mil at target range / 12 ) ) / time in seconds = target speed in fps
[ 5 mils * ( 24.5" / 12 ) ] / 1.5 seconds = 6.8 fps
Target speed in fps / 1.467 = target speed in mph
6.8 fps / 1.467 = 4.64 mph

2.2- Time of flight

(2 * range in feet) / Muzzle velocity + velocity at range = time of flight (seconds)
[ 2 * ( 680 yards * 3 ) ] / ( 3250 fps + 2100 fps ) = 0.76 sec

2.3- Lead in feet

Time of flight in seconds * target speed in fps = lead in feet
0.76 seconds * 6.8 fps = 5.2 feet

2.4- Lead in mills

(lead in feet * 12) / size of 1 mil at target's range = lead in mils
( 5.2 feet * 12 ) / 24.5" = 2.55 mils

3- Windage

The target is moving right to left and the wind left to right. In the Moving - 2 page, we saw that:

If the wind and the target are moving in opposite directions:

wind speed + target speed = wind speed to correct for
5 mph + ( 6.8 fps / 1.467 ) = 9.64 mph

Scope windage should be set for a left correction of 9.64 mph.


Results

Range: 680 yards

Lead: 2.55 mils

Windage: 9.64 mph to the left