I’ve killed elk with the 264 using 140 partitions, 120 ttsx, and 130 accubond. 140 partitions are my preference for elk, but I usually load 130 accubonds because I don’t only hunt elk. I did lose one with an accubond that I believe hit the shoulder based on her limp and good blood trail, at first. I really like the versatility of the cartridge for western hunting.
I cannot argue with your choice of the 140 Partition for Elk as I load that bullet in the Swede @ 2700 and the Creed @ 2800 and my Wife took 1 Bull with each load. Because I have not tried the 120TTSX yet, I wondered what you observed with that bullet that kept it out of 1st place for that application.