G W -
Have you noticed any change in the accuracy of your rifle loads, by putting ALL brass in a container together.
Brass from diff lots & or diff manufacturers vary in weight & physical makeup, and even hardness. It would take me a FEW tests to remove my 'apprehension' about using mixed brass.
There are other ways to keep brass segregated ( ! - oh !) than small ct. boxes
If it works for you that's all that matters.
Jerry