Learning how to become a better long range shooter? Here’s the next installment in the external ballistics theory mini series: elevation. When I talked about the vertical component of the trajectory, in Bullet Trajectory Part 1, I touched on firing elevation angle. I mentioned that when there is a firing elevation or depression angle, that is, when you’re firing with the barrel inclined upward (uphill) or downward (downhill), the bullet always hits higher than the aimed point. This happens when sights are zeroed on a level range, and then the shot is taken to a target positioned at the same distance but on a higher or lower ground, relative to the firing position, which forces the shooter to raise or lower the barrel to a degree. Long range precision shooters, such as hunters or military personnel, operating in mountainous or hilly terrain, or those operating in urban terrain, constantly deal with this phenomenon. The error induced by firing at an angle is considerable, and must always be taken into account, especially when extreme accuracy is needed and/or when shooting over long distances.
To realize how much elevation influences a shot, I’ll give you an example: shooting with a .308 Win rifle zeroed at 100yds on a flat range, firing from an elevation angle of 15° (barely noticeable if not measured with a gauge) induces an error of 2.5in at 500yds, 7.5in at 800yds and 13.4in at 1000yds. If you need extreme accuracy, that’s just enough margin of error to keep you off target. When the steepness of the elevation angle increases, the error dramatically increases, even at closer ranges. Shooting with the same rifle, zeroed at 100yds on a level range, with an elevation angle of 60°, you’ll shoot with an error of 5in just at 200yds (enough to keep you off the vital zone of a deer, for example) and 38in off at 500yds. Longer shots with such an angle are unlikely, but consider this: shooting with this angle at 1000yds would yield an error of 200 inches, literally enough to miss the “broad side of a barn!”
On part 2 of this article I’ll show you the true reason of the point of impact shifting when managing elevation angles with long range shooting.