I've always looked at multiple sources, and made a decision from there.
For example (I'm making these numbers up), Hodgdon may say 42-45 grains
Hornady, 41-43
Nosler 42-44.5
Lyman 40-43.5
I'd then consider if ANY of these take in to account the type of firearm (IE an AR10 VS a bolt gun and I'd lend more credence to that load data) or are they all for bolt guns? and I'd probably start at ~41 grains working my way up, expecting 45 (which is listed by hodgdons) to potentially be a little stout for a semi (but it may not be, your mileage may vary). Before doing any reloading, you need to make sure you understand what the signs of overpressure are, and you need to be willing to look at every case fired during load development. Sure you have some redundancy in your eyes, but personally, I've grown attached to having 2.