Fotis,
The tests I ran of a Chrony and ProChrono versus an Oehler were more extensive, taking place over three sessions. One of them paired the Oehler with a ProChrono all across one afternoon, from shortly after lunch until the sun wasn't all that far above the horizon. Varying sun is the hardest item for light-screen chronographs to deal with, and I ran a bunch of bullets from .17 caliber to over .30 caliber over both chronographs that afternoon. Neither chronograph "missed" any shots, and while individual shots varied between the two, the averages of strings of shots were pretty close. This is what we'd expect with one chronograph with screens only a foot apart, as opposed to a chronograph with a wider spacing.
The Chronys I tested didn't do so well, missing a number of shots as well as varying in recorded velocities more than the ProChrono.
Another test involves shooting a load that produces very consistent velocities in different light conditions, such as a partly cloudy day when the light varies from bright sun to cloudy. This is where I've found Chronys least reliable. One varied over 100 fps with the same load in sunny and cloudy light. Haven't had ProChronos do this.
Since Chronys are so popular, have also been at a local public range several times when people were having trouble with Chronys. In one instance the Chrony was showing velocities several hundred fps low with a known load, and no its wasn't due to a low battery, because the guy changed it, and then I lent him one of my spare batteries. Experienced that kind of stuff a number of times, which is why I eventually tried other lower-priced brands, and found ProChronos more reliable.
Haven't used a Chrony in about three years now, and perhaps they're far more reliable.
