Q: I’ve read that when shooting at a steep angle uphill or down that it is necessary to hold low on the animals or the bullet will go too high and sail over its back. Evidently then, the ground distance up or downhill is largely dependent upon the degree of slope angle involved. I am aware that surveyors correct everything to true horizontal distance to remove slope or angular errors, and that line of sight distance is exactly that. I intend buying a Leupold laser rangefinder which has an integral computer that calculates the angular distance. But can you explain to me just how much the angular distance really does vary from the horizontal distance?
A: If you are measuring distance up or down a hill, the slope distance will be greater than the actual horizontal distance. A slope with a 10 degree inclination will introduce an error of about 18 inches per 100 feet, which to the hunter is negligable. A 25 degree slope adds up to 28 feet per 100 yards, or 47 yards in 500 yards. From here on it really becomes a problem. By the time you get to a 45 degree slope the difference between slope distance and true horizontal distance is really critical – 88 feet per 100 yards. A measured 500 yards on a 45 degree inclination would correct out to about 354 yards in true horizontal distance. So as you can see, 500 yards isn’t always line of sight distance and if you use the amount of holdover required for 500 yards, you’ll overshoot the animal. Basically, the same amount of error applies when you’re shooting steeply downhill.