There were also reports that the factory ammo didn't get the advertised velocities--though my old Speer #6 manual contains chronograph tests they did with a lot of factory ammo, and the Winchester 140's came reasonably close. I've also found it close in the .two .264's I've owned. (The 100-grain load didn't come anywhere near specs in the Speer test, and was discontinued a number of years ago.) Many powders of the day weren't particular good for top velocities, consistent velocities in varying temperatures, or long barrel life.
No doubt much of the recent modest rebirth of the .264 is due to newer powders and better long-range bullets, especially in 6.5mm, the current favorite among many long-range shooters. Which is why I did the testing for my second HANDLOADER .264 article with target and higher-BC hunting bullets.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
