2700fps was the standard 150gr ball load for gov't ammo from 1906 through the modern era, even after they dropped the ill-starred M1 Ball load and adopted the M2 Ball load right before WWII (which was nothing more than the old WWI load but with a gilding metal jacket instead of cupro- nickel.
Did the original .300 loading truly generate 2700fps? If so, pressures had to have been high given the smaller case capacity compared to the Caliber .30 Ball, Model 1906 😊 case and the powders of the day. (Which were all what we would call fast to medium burn rate compared the wonderful selection we enjoy today.)
Anyone know the powders that were used in the two rounds circa-1920? That would address questions and limitations on pressure with the technology they had at that time.
