I've just completed a .260 Rem build on a Mauser action with a 1:9" twist, 27" Shillen barrel. I'm planning on shooting the 123 gr SMK because I'm doubtful anyting in the 130/140 gr weight class will properly stabilize. I'm getting pretty confused on what powder to use with the SMK. On hand I have H4831, Varget and IMR4064(I'd really rather not go buy more powder if I don't have to). I'm reading that Varget is too fast and H4831 is too slow. Can anyone set me straight on how these powders will perform inside 500 yds and what would be the better of the three to use.