Ballistics tables (in the reloading mauals and on the back of your ammuntition boxes are computer generated using the standard atmosphere and altitude variables for the bullet being used and the speeds listed. Nobody can know what a given load will do (velocity) coming out of your barrel. My brother and I have two revolvers - same make, same model, same barrel length and only a few serial numbers apart.
With the same ammo his gun shoots 100 fps slower than mine. The biggest difference between the two guns is the number of times they have been shot - Mine has been fired 20000 times more than his (the number of times I fired it while competing for two years (best guess))
Now - without running your loads over a chronograph to get the average velocity nobody can predict where your ammo will shoot unless they take your gun and site it in at a give range and then shoot it at each of the ranges in the chart enough times to provide an average for each of different ranges - and they would have to record Barometric pressure, temp, humidity, and make sure that the shots were fired at the same altitude and held in as close to the same manner as possible - the same shooter would have to shoot all of the shots.
