- Altitude
- Altitude at shooting conditions. This altitude
is used to calculate the standard density at the entered altitude. You should
enter an altitude density (in feet or meters) here. It is important to understand
that this is the
*only*value used to find the density of the atmosphere. The program assumes that whatever instrument provides the density altitude measurement takes into account all necessary variables. Temperature is not used to calculate the density since it is already taken into account in the density altitude. See Density altitude for more information. - Ballistic Coefficient
- The ballistic coefficient for the bullet being used. It is almost always obtained from the manufacturer, but can also be measured. The ballistic coefficient is represents the ratio of the drag of the standard (e.g. G1 standard bullet) bullet to that of the bullet you are shooting. A ballistic coefficient of 0.100 means that your bullet has 10 times the drag of the standard bullet.
- Bullet Library
- A drop down list showing all the buttons in the library. If a bullet is selected, the trajectory is run with the selected bullet. If "None" is selected, the entered BC, drag function and weight are used. Lapua bullets with "(CD)" in the description use the Drag Coefficients supplied by Lapua instead of the ballistic coefficient. Bullets with "(Litz)" in the description use Bryan Litz' BCs.
- Bullet Weight
- The weight of the bullet in grains (7000 grains per pound).
- Caliber
- The diameter of the bullet. This value is not used by the calculation, but is printed on output.
- Distance to Chronograph
- The distance from the firearm to the chronograph (typically midpoint) at which the velocities were measured. This value must be the same for both the high and low velocities.
- Drag function
- A drag function (or G function) provides the forces on a standard bullet for which the drag function was derived. A bullet's ballistic coefficient then relates the drag on any bullet to that of the standard bullet.
- Column One Units
- The units for the first column of drop windage and lead. For units of MOA, enter "1.0" and select "MOA" for the units. To match a scope turret unit, enter the value and units. For example, a scope that has click units of 1/4 MOA, enter "0.25" and select "MOA" for the units.
- Column Two Units
- Same as Column One Units (above) but for the second column.
- Line of Sight Angle
- The angle between the line of sight and level ground. This value
is used when shooting uphill or downhill. Value is a positive angle when shooting uphill
and a negative angle when shooting downhill. This value is
*not*used for the zero trajectory. It is assumed that the zero conditions are flat with zero line of sight angle and zero cant. - Low Velocity
- The muzzle velocity measured at a low temperature. If you know the muzzle velocity for only one temperature, you may enter the same value for the low and high velocities and low and high temperatures. The program will not perform any temperature correction for muzzle velocity. NOTE: I have simulated a low temperature (32 °F) shot by cooling bullets in and ice water bath (in a sealed bag!).
- Low Temperature
- The temperature at which the "Low Velocity" (above) was measured.
- High Velocity
- The muzzle velocity measured at a high temperature.
- High Temperature
- The temperature at which the "High Velocity" (above) was measured.
- Notes
- Text displayed at the top of the card. In order to keep the card small, this is the only output printed other than title and chart. Put what you need here to ensure that you know what the card is for.
- Ranges
- A comma separated list of ranges. The output includes a bullet drop and windage for each temperature, altitude combination at each range. Units of ranges are the same as for the zero range.
- Round Output to Whole Numbers
- Removes any part of the drop, windage or lead after the decimal point. This is useful when your drops match the scope click settings and you want the output to be in number of clicks.
- Sight Height
- The height of the sight (or scope) above or below from the centerline of the barrel. This is required because the bullet starts at a drop of -[Sight Height].
- Sight Offset
- The offset of the sight (or scope) to the left or right of the centerline of the barrel.
- Show Deltas
- If checked, only the differences in drop and windage from the zeroed trajectory are printed on output. Differences are in units of "Column One Units" and "Column Two Units". This option is most useful when you know the bullet drop and windage for your load at some condition and you want a table of corrections.
- Temperature
- A temperature used to calculate a muzzle velocity for output. This input is also used to calculate the speed of sound to find the value of the drag function. This input is not used to calculate density.
- Windage Correction for Zero Range
- If checked, the windage is changed to make the bullet cross the line of sight at the zero range -- zero windage at the zero range.
- Wind Angle
- The angle of the wind relative to downrange (0 degrees), 90 degrees is to the shooter's right, 180 is a head wind, and 270 degrees is to the shooter's left.
- Wind Speed 1, 2 or 3
- The speed of the wind. There are three wind inputs for three columns of wind deflection.
- Zero Altitude
- The altitude at which the firearm was zeroed. This value is used to find the atmospheric density.
- Zero Height
- The height of the zero point at the zero range.
- Zero Offset
- The offset of the bullet impact to the left (negative) or right (positive) of the target center at the zero conditions.
- Zero Range
- The range at which you wish the bullet to cross the line of sight. The units selected for the zero range are also applied to the "Ranges" value.
- Zero Temperature
- The temperature at which the firearm was zeroed. This value is used to find the muzzle velocity using linear interpolation between the high and low velocities. It is also used to find the mach number for interpolation into drag tables.
- Zero Wind Angle
- The angle of the zero wind relative to downrange (0 degrees), 90 degrees is to the shooter's right, 180 is a head wind, and 270 degrees is to the shooter's left.
- Zero Wind Speed
- Wind speed at time of zero.

The output table contains three windage values for each range specified.