I use JBM ballistics to check point of impact at 300 and 400 yards to get an idea of the appropriate zero range. The 1st bar is roughly 2.2MOA low and the second is 4.8MOA low. It is the zero distance than can manipulate the reticle and allow two different rifles to both have the 300 and 400yd bars be really close. For instance, I use the Leupold reticles with two different rifles shooting at roughly 2,850fps, but the 160AB in my 7mmSAUM is much sleeker than the 200BT from my 338WM. As a result, the 338 must be zeroed at a slightly greater distance for the 300/400 bars to line up with point of impact. If memory serves, the SAUM is right around 2" high at 100yds, while the 338WM impacts a bit higher at that distance. Both hit the 300yd and 400yd gongs with their appropriate aiming points.
