Re: Humidity ?
First off,
Lesson 1, environmental effects either need a very big swing, like the difference between sea level and going up to say 6000 ft before you see any real changes early, like inside 300 yards. The slight changes you posted in humidity, temperature and Barometric pressure aren't enough to show up at 300 yards and in... to demonstrate this simply go to JBM and run the numbers yourself. It's free.
Me just winging it with some basic 168gr numbers and your environmental data I have 16.7 MOA both ways at 600 yards and at 800 yards it changes slightly to 27.3 MOA versus 27.7. So that shows you what effects the weather has on your shots. This helps you understand that you can rule this out.
So you know, the second numbers you posted, as in the day it was raining JBM shows you need "less" dope than the range session before. At a 1000 yards which is actually below supersonic for you, the difference is 42.4 MOA for the rainy day, versus 43.1 MOA the time before. Anecdotally speaking.
For your reference: Bullets like:
High Temperatures
Low Barometric Pressure
High Humidity
Under these conditions the air molecules are excited and therefore spread out causing less air molecules for the bullet to run into per cubic foot of space.
They dislike:
Low Temps,
High Barometric Pressure
Low Humidity
As these conditions cause more parasitic drag on the round by packing more air molecules into the same cubic feet of space.
That is first off...
Now, you the look to your system or you. Were you being affected by the rain ?
Were your round wet, although higher chamber pressures should give you increased velocity, but we can't rule that out just yet.
Most importantly you need to test your scope. The water could have easily affected that, or you can be in the early stages of a problem. Leupolds have a bit of history with things like backlash, so it's possible you had a bit of memory in the springs and it didn't return to zero. The fact it worked last time means very little as it is a mechanical device and subject to failure.
Another question I would have, would be the stock. Is it the over-mold 700P or the H&S stock ? It is bedded, are the action screws torqued properly and have your checked ?
As you can see there is no easy answer, and something that requires you to look at it further. First another day at the range is needed to see if your zero changes again. If it does, I would test the scope across at least 48", an 8" box test will tell you nothing. Then you need to turn the knobs and check zero in a methodical way. If that turns out fine, I would chalk it up to the rain effecting you or the rounds ? But you can't rule you out. Maybe your cheek weld was off, maybe you were scrunching your shoulders, I don't know. But there is no simply answer other to say, I would suspect something in the system. It's not uncommon for your exact set up to drift a bit.
