Loadbooks are something I would recommend getting if they are available for a caliber you are loading for. It is for .243. I don’t rely on them solely, but it makes a great reference because they compile load info from as many sources as they can. This is valuable when you occasionally run into conflicting info. Or one manual doesn’t list info for a particular bullet/powder combo.
https://www.midwayusa.com/product/623361/loadbooks-usa-243-winchester-reloading-manual
https://www.midwayusa.com/product/623361/loadbooks-usa-243-winchester-reloading-manual