I have my copies of Lyman #45, #46, #49, & #50, along with Hornady 7-10, several Speer, Lee #2, Berger #1 & Nolser #2, #3, . Every one of them has some piece of knowledge in them that I have found no place else!
Then there are specialty manuals:
Elgin Gates had 3 or 4 for Silhouette shooting (one being "Accuracy for Handgun Shooting")
Hodgdon's hard bound shotgun Manual
SPG's Black powder cartridge manual
Hodgdon's No 24 was their last hard bound for metallic cartridges, and has a ton of info about Pyrodex & Black powder
Any Edition of Cartridges of the world by Franck C. Barns is worth its weight in silver.
And the greatest of all is P. O. Ackley's: "Handbook for Shooters & Reloaders Volume 1" any edition!
Like computers, every manual is obsolete before they were done making it! New powders come out every year (sometime every week) other great powders are discontinued all the time (one man at our club had several hundred pounds of "Red Diamond", discontinued after the first batch in the mid 60's, and he still used it until he died 2 years ago!)
This is why you use the computer web sites and Hodgdon's yearly magazine.
Ivan