Range tolerance: the margin you have before you miss the target, and why far away it shrinks to a few meters.
With the elevation for the estimated range, you hit even if the true distance is a little different.
50 cm target: 114 meters of margin at 400 m, only 16 at 1000 m.
At 800 m, a target 1 meter tall doubles the margin.
Sometimes the rangefinder isn't there, can't get a reading or reads wrong. Before you shoot, it pays to know how much margin you have: that is range tolerance.
You dial the elevation for the distance you think. If the target is actually a little closer, the shot goes higher; if it is a little farther, it goes lower. As long as the shot stays within the height of the target, you still hit it. The band of distances where this happens is the range tolerance.
Target 50 cm tall, aim at center, elevation correct for the distance shown:
| Distance | Hit from | to | Margin |
|---|---|---|---|
| 400 m | 332 m | 446 m | 114 m |
| 600 m | 572 m | 625 m | 53 m |
| 800 m | 785 m | 814 m | 29 m |
| 1000 m | 992 m | 1008 m | 16 m |
The app's demo profile: .308, 175 grain bullet, G7 BC 0.243, 800 m/s, 100 m zero. 15 °C, 1013 hPa, 0% humidity, 0° inclination, aim at center.
At 400 meters you can misjudge the range by about sixty meters and still hit. At 1000 meters an 8 meter error is enough to miss.
The margin is not the same both ways: at 400 meters there are 68 meters toward shorter ranges and 46 toward longer ones. The farther the bullet travels, the steeper it falls: if the target is farther than you think, the margin is smaller.
At 800 meters a 50 cm target leaves 29 meters of margin, from 785 to 814 m. With a target 1 meter tall the margin grows to 59 meters, from 769 to 828 m: it doubles.
Up close the range can be estimated, with the reticle or by eye. Far away it must be measured, and measured well: a rangefinder error of a few meters is a missed shot. In a match it helps you see which targets forgive and which do not.
Range tolerance changes with caliber, velocity and target size. The app calculates it for your profile and for every target in the Stage, and also shows it on a chart.
