Use some ballistic software such as Bergers; it's a free download.
Bullet drop's calculated from the bore axis. If a bullet drops 24 feet from a horizintal bore axis at 1000 yards, it'll probably have a maximum ordinate (height above line of sight) of about 8 to 9 feet. The high point will be at 500 to 600 yards down range. The bore's pointed at a point 24 feet above the 1000 yard target; at 500 yards, it's pointed about 12 feet above the line of sight. After the bullet leaves the barrel, it's always below the bore axis; it starts falling as soon as it's no longer in the barrel.
A good "rule of thumb" for longer ranges is, the maximum height above the line of sight is equal to about 1/3rd of the bullet's drop at the target.
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Last edited by Bart B.; March 18, 2013 at 04:48 PM.