I believe it exists now .9:30 am 35 yard zero ..half mil at 50 ..2 mils at 70 .temperature at a cool 75'..Come 12:30 pm temperature rises to 90' with the rifle and scope exposed to direct sunlight .held for the same dope on the same yardages and every shot was 5 to 6 yards short of the target .Decided to get to some shade by moving to the dry creek and setting up there a few hours later and the rifle was in the cool shade .The 50 and 70 came back to the original holdovers.Is this a phenomena or am I the only one experiencing this?