The original 7mm Remington Magnum factory loads were tested in 26" barrels--as were most cartridges in those days. They used what was later sold as IMR7828, but the testing as also done with copper crushers. When the industry later started the switch to piezo-electronic testing, it was found the pressures were very high--and the 7mm Remington Magnum's pressures also tended to vary more than many others rounds. Thus the eventual drop in factory ballistics.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
