Berger Manual lists only one load for 300 Win Mag 185 grain bullets that has a max velocity of 81.2 grains Ramshot Magnum and it produces 3040 fps.
Berger uses QuickLOAD for their manual data and QuickLOAD is usually a bit conservative on PMax.
Also, since velocity sells factory ammo and the Ramshot Magnum has the fastest velocity, I wouldn't be surprised if Berger loaded that powder close to PMax for their factory ammo.

Probably worth a try.