The key would be at comparable pressures. I certainly know that I have gotten a 338-06 to go faster than the load data you post, without any evidence of pushing the envelope. And since the 338-284 is a wildcat, there is now pressure standard.
Then variations between barrels comes into play; I have seen 100fps variation between rifles in the same barrel contour.
But all three are close enough to be peas in the same pod.
