I don't have any reloading manuals handy, since I'm at work, but I bet you could find some data online. Your Blue Dot load sounds about right as far as a reduced velocity would indicate, but I have no way to verify it. Gunwriter/experimenter/gunfanatic C.E. Harris wrote an article years ago about a general purpose light load he used in dozens of different cases, i.e., 257, 308, 243, 7mm, etc. He called it, "The Load", and it was something like twelve grains of Red Dot with any bullet weight normally used in the caliber. I guess he used most of them for plinking and small game loads, sounds like something fun to try. Hope this helps.
Papajohn