I don't know if it is true or not but I have also herd that fillers have changed, that is also what causes them to change data sometimes. I would also expect that updated and or new bullet designs have some to do with it as well. I like to have at least one current manual from a bullet maker like hornady or speer as well as one like the Lyman book because it gives you a variety of bullet makers as well as powders. Another option that I also like is the small caliber specific paper backs they usually cost less than ten bucks and supply data from powder, bullet, and mold makers. They are quite handy really.
* (Swinging club) Whack! whack! whack! *
Nope, the old nag's still dead .