This thread kinda got me thinking about your numbers, so I fired up my Sierra I-6 program and ran the numbers. I started with your home figures...4500 feet, 60 degrees, and the standard I-6 baro and humidity (70% and 29.53). I used the 142 SMK at 3170 and a sight height of 2.25 (educated guess), and a 100 yard zero. I come up with 12.9 up at 768 yards.
I swithced to 17 degrees, baro of 29.00 ("front comming in), and 3500 feet and came up with 13.3 moa up.
Now , I am not sure about the shooting up hill, down hill numbers, cuz I don't know. But what I do know is that you would need LESS dial up. I am not sure if that lessens your dial ups 1/2 MOA or 3 MOA, but it is LESS.
SO, first, the environmental changes should only have changed your impact piont a couple of inches.
Second....if the I-6 is correct.....dialing 14MOA should have put you HIGH at 768 no matter what the environmental properties were.
By my calculations, if I guess at 10% less dial up due to the up/down hill component, and that is all it is, a guess, and the .7 MOA the I-6 says you were off, you should have actually missed HIGH, not low. Now, that is figuring that your scope goes EXACTLY 14 MOA, and everything else, including Jupiter and Mars lines up!!
I just bumped back to your origonal post and noticed that your range is at a 10 degree decline, and the shot was at a 19 degree decline.....so you dialups at your home range should have been LESS than the I-6 says (12.9 MOA) and cettainly less than 14MOA. And the actual shot on the animal should hve been even less.
Question....are you sure about your chrono readings? I need to reduce the MV to 3070 with your home range numbers to make 14 MOA dialup work...and that doesn't take into account the 10 degree down.