At this year's Nationals, the US Army team set a team record for service rifles at 1000 yards using AR10's and 185-gr. Berger bullets in their 20 inch barrels. Betcha a bag of goodies their handloads were up the the blue pill pressure range to get enough muzzle velocity to keep that bullet supersonic through the paper 1000 yards down range. 'Course all the service teams have a long track record of loading match ammo way, way over SAAMI and MIL-SPEC levels for the cartridge used.
I was told the Varget charge they are using for their 185 grain bullet. Its what I use for 168's!
This was AMU 600 yard brass, stuff I picked up at Camp Perry
This was USMC 600 yard brass, again picked up at Camp Perry