Strange happening

The wife, myself, and daughter went to a match this past weekend. As per usual, when we get to the location, I use my kestrel Drop and enter the current weather conditions. So we do that and pull up our dope. All three of us were shooting over the top of the targets. I had to drop my scope down 2 or 3 tenths at 600. Teresa about the same and my daughters 243, I had to crank down half a mil. Just for the match, on my daughters rifle, I trued it to the actual drop we were seeing at 600 so it would be calibrated for what was going on. Otherwise we would have to quickly shoot and verify every distance and write down what the dope was. When I trued it, it jumped her velocity up just under 200 fps. CRAZY. I probably wouldnt have dont that but I have the original MV written down in dope book.

I have shot this place before and didnt see this issue a month ago. I updated local conditions as did my wife. So we were using two different devices same calculator that gave similar answers that were apparently off.

Truing her data worked for that match because my daughter came in 22nd for the match.

Any ideas? I am about to break down and go back to the magneto speed just to see if anything is changed.

Modern electronics are a wonderful thing. Certainly without them, we would never have landed on the moon.
Certainly people like me would never leave a dock before daylight, with much hope to find a specific spot way beyond sight of land.
That said, when the captain of a merchant vessel, sits for the exam upgrading his license to a higher level,
he wont be permitted to rely on modern electronics for his answers. He will do the math or fail the exam.
Now when were simply getting the boat to that buoy over there say a mile away, we might simply aim the boat toward the buoy.
If wind and current are strong today, we simply steer a little harder.
If we had decided to get fancy and use all the neat and expensive electronics we have to reach that buoy, then we are then playing a different game called (find the buoy without looking.)
And theres no guarantee we will ever actually reach that freaking buoy. lol
The KISS SYSTEM, it works every time.

As I was reading this, before you said it at the end; the first thing I thought of was "He doesn't actually know what his velocity is, or is using the wrong BC". :)

So for the velocity:
Weather, and specifically temp, can play a big roll in velocities. Don't know what you are using, but most folks think that an "extreme" powder is dead stable and a universal thing. Well they aren't stable in every case, and they aren't dead stable. They try and compensate burning rates with temp. Even in a perfect application, that means some times they over or under compensate burning speed.
Likewise, despite what gets bantered unofficially online, burning rates really aren't that tight, and can't be. Canister-grade powder that we use, many times is a blended product; and moisture content can change even from a Sealed container. This further aggravates burning rates. So is your velocity from THIS current lot of powder, or another?

Little details can really be really aggravating. ;)