FWIW do you guys have an additional nut on the powder adjustment? Previously mine would still tighten in process of actuation, added another nut and the issue went away.
Also are you doing any extra flaring with the powder measure? I do all my flaring with the Lee Die loaded with MBF expansion, and just have the powder drop go for actuation, but no additional flaring.
Just spitballing ideas here. Good luck with your powder measures.