Hodgdon Data Manual #26 is dated maybe as late as 1992 or later, although there are earlier editions.
You can find old data manuals in your local library. Generally, newer manuals are reducing loads -- most of the time by 10%.
There's a heap of data available online. It pays to do some research into the loads you're working up. Using one source for load data is like depending on one encylopedia to write your PhD dissertation. -- It might be accurate data, but it's hardly going to give you a perspective on what's being used these days.
As regards conflicting velocities -- barrel length, temperature, barrel itself, bullet type, and various other factors can affect that data.
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