Know your equipment numbers and fps put them into a ballistic program and it pretty much spits out the calculation.
^^That ain't D.O.P.E.^^
That is a calculated trajectory. You start with that, then go shoot the distances to get DOPE. Data On Previous Engagement. Have the calculations printed, make the correction it gave, write down the result. Was it center, high, or low. Move to the next target at a farther distance. If everything shot matches everything predicted, then things are easy. When some, or all corrections do not match then a number of factors can be the cause.
1. MV is too high or too low, adjust to make the calculator match what was shot.
2. BC is too high or too low, adjust to make the calculator match what was shot.
3. Tracking errors in the scope. This is when some distances match and some do not. For instance, 200, 300, 400, 600, and 800 match. So there was a tracking error at 500 yard correction and 700 yard correction.
4. Environmental conditions in the calculator did not match the environmental conditions the day the range was shot.
You have to shoot it to get real DOPE.