All this talk of wind drift and such has me thinking back to the late 80s.  M-14s and M1As ruled, guys had built Garands trying to compete with them.  From 600yds on a windy day the mouse guns were hitting targets next door to the one they were shooting at!  600 is the longest range I've shot from at Perry.  I did pretty good back then, I had a Devine M1A that I'd built up very much like my Garand.  I didn't know the collector value of the Devine, sold it when going to college in the 90s.  I don't think I'll be sticking around for your long range attempt Paul, but I'll be anxious to see how it goes for you.