We were discussing this today. Last weekend I shot my 77 grain SMK load out to 600 with my 1-4 Trijicon and felt solid it was a good fit for me. (and it is)

Today we went back out and I was shooting another 223 with 75 grain HPBT’s and the wind got both of us. Had to go to the 75 Amax to beat it at 500 and especially 600. Got us to thinking about the 6.5 Grendel. I’ve already taken the 6.5 CM to 1000 with a 140 grain ELD at just over 2300 FPS so the Grendel is finally starting to look good to me. The higher BC cheating the wind is reason enough.