Jon Wolfe did some testing with 6.5 CM in an M14 a few years back. He concluded the powders used in 6.5 CM burned too slowly and resulted in too much pressure at the gas port. He settled instead on 6 XC running Varget. I would trust him over anything out out by Springfield Armory.
Be careful with your loads in case you bend the OP rod. On the other hand, if you do Springfield will replace it.