Haven’t tried them yet.
I have 338-416 Rigby Improved (my own version) 338WM & 338-06.
So, when I get my hands on some, the Rigby will give them a try, that ALWAYS tells me if a bullet is up for the task...Berger’s in it are not.
Don’t know if it’s worthwhile trying them in the WM. Velocities would be pretty low and the rig I have is not truly LR, but have shot it to 800 in the past.
What cartridge(s) did you work with?