First of all, if it likes the Barnes load, just smile and feed it that.

I have worked with a few .308's. As far as my best luck with powders, I would put them in this order:
(1) H4895
(2) RL-15
(3) Varget

A guy that I know has worked up more .308 loads than anyone I personally know, swears buy the new IMR 8208. He told me that he has seen 2 mysteries over the years that he hasn't figured out yet, First is how is it that FGMM ammo shoots so well in so many .308's, and Second why does 8208 work so well in so many .308's? I haven't tried it yet but I fully plan to.