Greetings @Nathan F,
This is exactly what I do for 90% of my loads although I use the Hodgdons site which presents the same data plus other powders as well. For the 50BMG there is no data for Trail Boss so the Hodgdons system for load development can be used. I don't use Trail Boss currently but do use AR2206H for reduced loads for some of my old soldiers (.303 and others) and soft target loads for my .308. Hodgdons offers a method for developing these as well where they are below the start loads in their data. Much safer than copying loads from the interweb chat groups.
Regards Grandpamac.
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