I just recently tried a bunch of different loads for the new 6.5X 284.
I did load some different loads with the H4831SC and got to 51.5 gr. before I started seeing pressures. Not terrible pressures but still enough to say stop.
They shot good groups but was topping out at around 2900 fps through my chronograph. I also loaded 49gr. of RL17 which shot some great groups as well as Hodgons Hybrid 100V at 49 gr. Both of these shot great groups but was lacking the fps I was hoping for. My best groups and greatest fps came from Retumbo at 58.5 gr. A couple of reasons I decided to stick with this load. It shot great groups. It gave me the best velocity. (3020 fps with 16fps extreme spread) It is also one of the extreme powder lines not affected by temperatures. Hardly shows any signs of pressure even at 58.5 gr. I am shooting it through a new Savage 111 LRH with a 24" barrel and was quite surprised to see this velocity. This load is shooting a 5/8" group at 200 yd. and for me that is pretty darn good.
Hope something here helps. Let me know what ya end up using.
Oh ya just FYI all of these loads were with the 140gr Berger Hunting Bullet and seated to COAL of 3.120.
THE GUN THEORY!!!!!!
Better to have it and not need it, than to need it and not have it!!!!!