Well I missed my 600 yard shot. This rifle has had me scratching my head the last few weeks, so I guess I shouldn't be shocked.
Tikka t3x lite with a 16" Preferred Barrels 22CM in a ctr stock.
Alpha brass, 88gr ELD-m
SWFA 3-9 in a Spuhr tikka mount
Griffin gp7 suppressor.
AG pint size with git-lite, leofoto tripod for rear support.
Had a light 4-6mph wind from 1oclock, held just right of center, and missed high and right. Previously my load had been around 2995, but yesterday I shot 18 rounds over the chrono with an average of 2916 and sd of 8, so I adjusted my data in AB, I know it's unlikely that the next round happened to be 2995, but that would explain the high part of the miss. Definitely interested to shoot over the chrono on paper again after the challenge is over.
Edit for day one: After some thought and watching the video again, I think my elevation was fine, and that I just misread the wind. Those head winds are tough.
Day two:
Found a nice area to set up off an old logging road. I had to fudge my range a little bit, 629 yards, any closer and I either could not see my target, or could not find a suitable position. Shot was a 5 degree downhill shot, on a 30ish degree hill. Found a nice stump and setup my tripod for front with git lite pint size for rear, super stable, low kneel behind the stump.

DA: 8200
71*F
Wind: I was getting blocked by trees, so my kestrel was only picking up 3-5mph, but the bush 20 yards away in the open was moving way more, and I could hear it in the trees, so I knew it had to be more. Plus accounting for my bullet being way higher off the ground shooting across a draw, I estimated 9mph from the 10:30.

I should have put my .5 hash on the left edge, but I thought maybe the wind was dying a bit, so I put my .5 on center for a low end bracket.
Missed just off the right edge! I should have stuck by my .7 call

Since the challenge was officially over for me, I had to send a few more. Put 1.0 on center and missed off the left side

, proceeded to put 5 on plate with .5 favoring the left side of center on the plate (which was about .4 wide). I have been trying to take a cold bore shot at between 6 and 700 yards for the last month or so, and been about 50%, definitely going to stick with that, but maybe between 5 and 600 for a while until my percentage is higher.