During my years with a chronogaph, I have noticed three things,
First, almost all rifles are slower then the published date.
Second, there is a much smaller group that will about equal published velocities.
And third, there is very small group that will exceed published data.
Once you get over the shock, then you can enjoy watching your friend's face when he shoots his super velocity wize banger over your screens and finds his dream gun is 2 - 300 fps off the expected pace. Odds are it will happen just that way. Welcome to reality.
You will also see such things as a light load shooting faster then a load 1 or 2 grains heavier. Yep, saw it with my 45/70 summer before last, all loads being well within safe loading guide lines. Checked in on the forum and what do you know it is not the first time this has happened.
You will see loads during a test series, suddenly begin to show wide swings in Velocity even before you have reached max published load figures. Yep, it could happen and when it does it is time to back off with that powder no matter what the book says!
Enjoy that chronograph, they are great learning tools.
Keep em coming!
Crusty Deary Ol'Coot