This is a powerful and flexible program, but the usual rule applies - garbage in, garbage out.
READ THE TEXT AT THE BOTTOM OF THE PAGE TO ENSURE YOU GET USEFUL RESULTS
Any BC entered must be appropriate for the standard projectile chosen. So, if you want to use the G1 Ballistic Coefficients usually quoted by bullet manufacturers for your bullet of interest, choose the RFB standard projectile.
If the shape of your bullet is similar to one of the standard projectiles shown above, the BC for your bullet relative to that standard projectile will be very close to the sectional density* of your bullet. So you only need to enter the bullet's weight and diameter, and the program can generate a BC to use in its calculations. This is handy if (as is probable) you don't know the BC of your bullet relative to that standard projectile. So for example, if you choose the SBT (G7) standard projectile because your bullet of interest is a target bullet with a boat-tail and a secant nose and looks like the SBT projectile pictured above, you will get excellent results by just entering the weight and diameter of the bullet and leaving the BC field blank.
But if you do enter a BC, this will take precedence over BC generated from the bullet's weight and diameter, so make sure that any entered BC is relative to the standard projectile chosen.
You will probably get better results choosing a standard projectile similar in shape to that of your bullet and just entering the bullet weight and diameter, rather than use the usual G1 Ballistic Coefficient for the RFB projectile shape as most ballistics programs do. With this program, you can choose either route.
Values entered for the local atmospheric pressure (anything other than 29.92 in. Hg) will take precedence over local pressures estimated from the barometric pressure and the altitude.
Ballistic data will be generated every 50 yards up to 1000 yards, or every 10 yards up to 200 yards if 22LR is chosen.
Additional data will be calculated for the Custom range entered.
Also calculated is the Launch Angle of the bullet as it leaves the barrel. This is the angle of the bore axis to the horizontal, giving you an absolute sighting-in angle relative to the horizontal, rather than angles or drops relative to a zero range. This is also a useful feature if you want to see what the vertical dispersion at the target (in MOA) will be due to your measured spread in muzzle velocity.
*Sectional density is the bullet weight in pounds (1 pound = 7000 grains) divided by the square of the bullet diameter in inches.