There are fast guns and slow guns. There also fast chronographs and slow chronographs. All results posted are within margins of error.
I shoot a lot of 22 LR over the chrono looking for the magic, most accurate ammo. I have several rifles and they all shoot the same exact lot of ammos at different speeds.
When I get a nice day I'm going to chrono using both my Garmin and Competition Electronics at the same time just for fun.