Ballistic Coefficient (BC): Typically obtained from the manufacturer, this value represents the ratio of dragfor a given bullet. The ballistics library contains ballistic coefficients for thousands of different projectiles, but if you don’t find yours there, contact your manufacturer for this number. To access
the ballistics library, tap the blue disclosure to the right of the Ballistic Coefficient field.
Bullet Diameter: The actual diameter of the bullet in inches. Not caliber. This value is used primarily for informational purposes, as this information is already considered in the ballistic coefficient. You’ll need to know the correct diameter if choosing a bullet from the projectiles library. The loads library is, however, sorted by caliber, allowing you to choose your particular cartridge type without knowing the diameter.
Bullet Weight: The weight of the bullet in grains (7000 grains is equal to one pound). This is used primarily for informational purposes, as this information is already
considered in the ballistic coefficient. It is filled in when you select a projectile or load from the ballistics library.
Native Drag Model: A ballistic coefficient’s value is based on a specific drag model; e.g. G1, G7, etc. The drag model that goes with the supplied BC is the native drag model. Most manufacturers provide BCs with a G1 native drag model, however some are finally publishing G7 drag models as well. Be sure that the drag model you specify matches the one that the manufacturer used in publishing the ballistic coefficient, otherwise the calculation will be off.
Muzzle Velocity: The velocity of the bullet as it leaves the muzzle of your rifle. Most manufacturers print average velocities on their boxes, or provide this information on their website. For more accurate results, you might consider using a chronograph to measure actual velocity. Velocity can change by a number of factors including barrel length, temperature, and even the amount of fouling in your rifle barrel, so if you’re serious about pin-point accuracy, you should invest in a good chronograph and practice consistent barrel cleaning after each shoot.
Chronograph: Velocity usually isn’t measured right at the muzzle, but rather by a chronograph placed a number of feet in front of the muzzle. As a result, the actual muzzle velocity may be slightly higher than that recorded by the chronograph. By entering the chronograph’s distance from the muzzle in this field, Ballistic will calculate the actual muzzle velocity from the velocity you provided and the distance supplied in this field. If you are measuring velocity right at the muzzle, set this value to zero.
Use Drag Model: One of Ballistic’s more advanced features is to allow you to seamlessly convert from one drag model to another. If you would like to convert this projectile’s BC to fit some other drag model, choose the drag model you’d like to convert it to here. The BC will be adjusted based on the drag model selected and the given muzzle velocity.
Zero Range: The range at which the rifle is zeroed at, with the given ammunition. It is expected that the rifle’s point of impact will match the rifle’s line of sight at this range, at zero angles.
Sight Height: The distance between the centerline of the barrel and the center of the scope or sight. This is very important, as the bullet’s drop will begin at this distance out of the muzzle.
LOS Angle: Line of sight angle (your shooting angle). This is the angle at which your rifle is aimed. A value from -90 to +90 is acceptable here. The shooting angle dramatically changes the gravitational effect of the bullet, ultimately changing your trajectory. If shooting straight, leave this value at zero.
Zero Atmosphere: The climate and altitude at which you zeroed the rifle at. Pressure, humidity, and other factors can affect the density of air, which affected how the bullet traveled when you zeroed the rifle. When this is disabled (default), no corrections are made to account for this. If you have this information available, however, it will allow you to fine-tune the output to account for zeroing in one climate and altitude (e.g. summer, at 300 ft above sea level) and shooting in another (e.g. winter, at sea level).
Current Atmosphere: The current climate andaltitude you are shooting at. Pressure, humidity, and other factors can affect the density of air, ultimately affecting the amount of drag on the bullet. By specifying a current atmosphere, Ballistic adjusts the BC of the bullet to compensate for this. Leaving this option disabled will cause Ballistic to forego any corrections.
Pressure is Absolute: If the pressure being provided is the absolute pressure given elevation, turn this switch on. If the pressure needs to be corrected (e.g. if it is a station pressure, reported elsewhere), leave it off.
Wind Velocity: The speed of the wind. This is used to account for windage (in crosswinds) and also adjust the bullet’s velocity (in headwinds).
Upwind Velocity: Vertical wind. If your range has upwind flags, you can enter the estimated speed of the wind traveling upward (or downward) into this field, and your elevation will be adjusted to compensate.
Wind Angle: The angle of the wind direction. Changing this value can affect both windage and trajectory bya factor of the wind speed. By default, the wind angle indicates the direction of the wind, however you can change this in settings to make it reflect the origin of the wind.
Wind Position: The position at which the strongest wind is crossing; by default, this is set to “Muzzle”, but canalso be set to “Midrange” or “Downrange”. Ballistic will adjust your windage (and elevation, if an upwind is specified) based on where the wind is strongest. This option is only used when using simple wind. When using the advanced wind kit, you can specify the exact position of the wind in a number of scenarios.
Maximum Range: The maximum range to be calculated and displayed in both the trajectory calculations and charts. NOTE: If you put a minus sign before the range (e.g. -1000), the calculation will show only that specific range.
Minimum Range: The minimum range to be displayed in the trajectory calculation. This is useful if you are displaying a lot of data, and want to focus on a particular set of distances.
Range Increment: The increment (step) to be used in displaying the calculated trajectory. E.g., every 25 yards.
Vital Zone Radius: The size of the vital “kill zone” of the target, used to calculate point blank range. For example, if your vital zone radius is 5 inches, your point blank range will span from your zero to the lowest and highest ranges at which you can hit the target inside that radius.
Elevation / Windage Units: The units in which to display elevation and windage. This can be MOA, MIL, or a number of other values including a custom click value.
Elevation / Windage Turret Value: Some scopes are not exact; that is, one click does not necessarily equal exactly one MOA or one Mil. If you know the actual click value of your scope turrets (for example .982), you can enter it here. The output units (regardless of whether they’re MOA, mRad, or anything else) will automatically be divided by this value, to give you an accurate number of clicks. For example, if your turret value is 1/3 of a click and your output is 5 MOA, then enter .333 in this field. The output will read 15.01 (5 / .333). NOTE: Versions < 4.7 multiply this value, rather than divide it. Division is the correct way to compensate for turret correction, so if you’re using an older version below 4.7, you’d enter 3.333 instead of .333.
Zero Height / Zero Offset: The height and offset of the zero point at the zero range. For example, if your zero is 100 yards, and you want to assume the bullet travels 10″ above zero at 100 yards, you’d set the zero height value to 10. If you want the bullet to be 6″ offset horizontally at your zero, set the zero offset.
Windage is Zeroed: When calculating spin drift, enabling this option will tell the application that you’ve zeroed your windage at your zero range. This is particularly useful if calculating spin drift without wind.
Miller Stability: This is a bullet stability calculation, used to determine if your barrel twist can stabilize a given projectile. Stable values range from 1.4 to 2.0.