I get a lot of those.
Errors.
I found sometimes I have the Chrono too close to the muzzle and the blast messes with it.
F1 is what I use.
I also found I get more errors on cloudy days.
Something I have done to eliminate a lot of Errors is to not install the sun screens.
Leave them off and just install the rods.
Shoot between the rods and not too low or too high and I get best readings that way.
One guy on another Forum eliminated his errors by mounting his Chronograph
Upside down and on a solid piece of plywood painted white.
I have not tried that but he swore it worked on sunny and cloudy days.
Errors.
I found sometimes I have the Chrono too close to the muzzle and the blast messes with it.
F1 is what I use.
I also found I get more errors on cloudy days.
Something I have done to eliminate a lot of Errors is to not install the sun screens.
Leave them off and just install the rods.
Shoot between the rods and not too low or too high and I get best readings that way.
One guy on another Forum eliminated his errors by mounting his Chronograph
Upside down and on a solid piece of plywood painted white.
I have not tried that but he swore it worked on sunny and cloudy days.