The powder and bullet manufacturers reduced velocities in some cartridges because of better and more accurate methods of measuring pressure. In other words unless I’m shooting a obsolete/uncommon cartridge where only older data is available, the newer manuals provide more accurate—and safer—load data.
Equally important is that powders of the same label manufactured 50-60 years ago don’t necessarily have the same burn rates or energy as current manufacture. IMR4350 50 years ago isn’t the same as it is today, for example. My H4831 manufactured in the mid 90’s produces higher velocities than current H4831, using the same brass in the same rifle.
Where possible I rely on the more recent data.
I like the Hodgdon manual, but own 4-5 dozen manuals and often consult them to get a “feel” for a consensus among different pressure barrels.
Last edited by alpinecrick; 10/02/22.
