Well, I got out there at 0630, and got home at 1045. It was already 113* before I left out there, and.... DAMN! Was it was weird out there...
Everything was different. I made and tested that 178 ELD-X load, and it was 50*, I was running the altitude for where I was (camp location) at 1390 feet, baro pressure was 29.80 in/Hg, and humidity was almost nothing. .308 Win load, badass to the bone, like a laser. 8.5 mils of drop at 850 yards, and I confirmed that the very next day after I finalized that load...
Okay, so today... Fuckin' WEIRD. This thing was 7.0 mils of drop at 850 yards. I've never had a .308 Win load that will do that. At first, I dialed 8.5, and I was shooting way over the steel. I dialed it back to 0, and just started holding, until I was on target. Once 7.0 even was determined to be the magic hold, I dialed 7.0 mils, and whack after whack on the steel. Unreal for a .308 Win load.
Weather - as soon as I figured that drop out: At the time right after shooting and re-doping it, it was 105*, baro was 28.38 in/Hg, altitude at the long-distance location is actually 1458 feet, and humidity was 22.6%.
Just plugging weather into the calculator (alone, just the weather differences) brings the drop to 7.7mils at 850 yards. Play with the muzzle velocity (2530 fps when I made this load, weather data up top)... I mess with the muzzle velocity in the calculator, along with the weather changes, and it's 2630 fps to make 850 yards a 7.0 mil drop correction...
The 18" Grendel was just as weird, but I didn't put the time into that one to figure it out. Eff it. I'll wait 'til it's cooler to mess with that.