as our company works with sac files, this is causing an issue while processing the data, we managed to correct it with a python script, but it would be nice to have all minissed files with correct starts and end times, follow the python Script to convert to sac and fix the start and end times:
the existence of the inexact start times is an artifact of the program which writes the files themselves, since there is no internal coordination between how separate channels are written.
we will have a look to see how this can be mitigated, but cannot commit to providing such an enhancement.
in the meantime, you should integrate your conversion script into your data-processing pipeline to guarantee that the start times in your SAC files are coincident.