Loads from a 70's Hornady manual use quite a bit more powder than the new manual for the same caliber, same powder and same weight bullets. Same is true for the old and new Speer manuals. My assumption is all the newer loading manuals use lighter loads to ensure a greater degree of safety and less chance of liability issues and law suits. Am I correct? Or, has the burn rate of powder changed over the years enough to warrant changing the load data to stay within safe pressure ranges?