What kind of velocities are you getting out of the 168 bergers ?
My top 3 choices would be Imr4350, RL17, and H4350. On the slower side of things I would go Imr4831, H4831sc, and Alliant PP4000MR. With 7828 I can't see you being able to get enough in the case. H1000 and Retumbo are way to slow, that's about like using US869 in a 300wm.