My 6.5mm CMs - 12 LRP, 12 FV and 10T-SR - shoot the 143 ELD-X bullets very accurately.
H4350 and IMR4451 both shot very well, averaging under 0.325 each for around 25 5-round groups at 100 yards. Best loads were under 0.300.
IMR 4350 shot just under 0.500 in two of the three rifles.
H4831 SC should also perform well. I haven't shot the 143 ELD-Xs with it but it performed well with the 147 ELD-Ms and the 140 ELD-Ms.
The H4350 and H4831 powders are temperature insensitive so they would be great for hunting loads, since you never know how cold it will be when you are stalking or in a blind.