"one, good, written manual to be necessary"
I would agree with this..... Only, where is that one?
I have many, many manuals. Some for lead data, some for 'Military Spec' data. As soon as I find one that fits my needs, I get another caliber/chambering that is not covered.
Then there is the problem of who to trust. Add to this tpyos or shifted data lines.
When I start looking at data for a new (to me) chambering, I want as many sources as I can get. I evaluate and list and sort and re-evauate, over and over before I determine what powder I will first. Old people with more time than money do this
Be safe,
OSOK