I too have found the lighting to play with my chrono`s so I`ve been running a "proof" screen lately. I wanted to see if the readings are off or are "true" even though the screens are haveing trouble picking up the bullet. The units seem to be as accurate when lighting is to the point they drop a shot now and then, as it is when the light is optimum. Although the individual shots may show some spread in velocity that appears to be wide, the reality is they are only a percent or so apart and are very close over all.
Here are some the readings I got yesterday between 1:30 pm and ~ 5 pm. The rifle was a 708 with 2 different bullet wgts and this was during load work up.
Pact-------Shooting Chroney
2905 fps---2891fps
2960 fps---2954 fps
2737 fps---2781 fps
2783 fps---2774 fps
So much for the one is more accurate line. I try to keep the screens shaded but in the late afternoon the screens are pointing at the sun as the range runs east/west.

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