One item I might add is that I've pretty much settled on Varget for lighter bullets and Big Game for heavier bullets because they've proven more cold-resistant other powders, including Reloder 15 and 17.
And yes, I've tried Big Game with Woodleigh 320's that gunner500 mentions, and it works just as well as Reloder 17. From the 23.6-inch barrel of my CZ 550 it gets right around 2350 fps, and probably be very close to the 2400 he gets in his 25-inch barrel.
Have also hunted with Big Game and 286's in over-100 degree heat in Tanzania, with no problems.
