If I can get 3150 from a 6GT with a 108 Berger, a 23" barrel, following Hodgdon data, plus not physically observing any pressure signs whatsoever, a case with 13-14grns more h2o capacity, can do it easily. Varget isn't the answer though, not in 6xc, 6cm, 243, or 6mm Rem. H4350 is the fastest burner I'd use. If you want the real potential of a 6mm Remington, RL16, RL17, N555, Ramshot Hunter, and Staball 6.5 on the fast side of powders, on the slower side, RL22, 23, 26, N560, N565, Imr7828ssc, MRP, Magpro, Magnum, and Grand. My money says Staball 6.5, RL26, and Grand, give the highest accurate velocity. I've used H1000 and Retumbo before, in the 6mm Remington, and they shoot great as well, and are pretty fast, but more compressed than most people care for.