John M is right on this one as well.

To check my Chrony I put a couple of 22lr's over it first.

I have a "red" Chrony,my mate has a "green" chrony as well as an Ohler.

We lined the three up (end to end) and you would be surprised have close the three were.Less than 25 fps between them.

It is nice to know your velocity but not that important as you found.

I just use it to say "I want 2250 fps out of my 404" or "3000 fps out of my 8x68s".

There must have been some lies around before Chrony's were readily available.