You won' t win with that thinking....do this: sight in your slug gun for 40 yards. That should cover any target from 10 to 65 yards. Then shoot the gun at 75 and 100 yards to see the actual drop.

I' d be reluctant to shoot over 100 yards.....

After you know what the drop is at 75 and 100, you must judge the distance of actual shots and hold high accordingly.