It's a good idea to verify the chrony by using some 22LR Match ammo. It tends to be very close to published velocities.
Some cartridges seem to run closer to published numbers than others... I have found factory 17HMR and 7mm-08 to both run very close to box numbers. .204Ruger and 22-250, not so much.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.