What shape of pin ENDS do you use? (Brand?)
Rounded pins didn't seem to get the primer pockets clean in the corners for me,
I use pins that are square end with a slight radius break from side to end now,
They seem to get the corners of the primer pockets cleaner.
Smaller diameter pins get those flash holes cleaner also.
When I use a round container (PVC Pipe) with no 'Stir' blades/bumps installed,
The brass took a lot longer, but came out high polished.
The 8 sided drum that I started with cleaned a little faster, but it didnt polish quite as well, really clean when I stopped, just not quite as much polish when cleaned.
Now I use a drum with blades to mix brass.
I've tried long blades to mix up brass, but short blades in the drum seem to work as well and the brass comes out just as clean,
And the shorter the blades the higher the polish I'm seeing.
The only thing I can think of is the less mixing, the more time the pins have to rub/polish the cases instead of being constantly displaced and have to settle back in, compact, and clean/polish the cases...
Just my theroy.
At the recomendation of the guys here, I'm using citric acid in the water,
And it makes a BIG difference!
A little industral hand cleaner (cheaper & more concentrated than Dawn) and some citric acid based parts cleaner, and they are ready to work in about two hours, high polish takes longer.