You aren't going to get a fmj to shoot better than that. Get some 69 grain match kings. Your powder is fine. Nothing inherently wrong with spherical powder accuracy wise.
1300 asl. I dont normally load the 208 eld as my typical choice is the 185 juggernaut. I did take the 208's out to 800 with no apparent stability issues.
I'm looking for a midweight 18 inch 6.5 grendel ar barrel to complete a build for my son. Shoot me a message if anyone has one laying around, or knows of a source.
Custom rem 700, 11 twist bartlein barrel at 22 inches. I load them over 44.4 grains xbr8208 in lapua brass. They run 2930 fps and are outstanding out to 900. Never tried them further.