Yep, agreed.

Pete, I think that what the OP is aiming (sic!) to achieve is to ensure that the rifle is safely under the limit with any pellet to keep legal and that will entail power testing with as wide a range of pellets as possible, but, most especially, with the ones most likely to attain higher energy figures.

I agree, the pellet that I USE for shooting will be the one that accuracy testing has revealed to be the most accurate in my gun / barrel combination.