I have picked up a batch of .22 brass that has turned a dull blackish color from exposure to weather. Along with all that,, I like to take fired brass,, or whatever,, and clean the .22 RF brass first. THEN I de-rim.
And as noted,, then you anneal the brass.
When you anneal the brass,, it's also burn off the lube used to de-rim.

I used my new pot yesterday to anneal a bunch of de-rimmed brass. Afterwards,, I ran them through a good wet tumble cleaning. SS pins, LemiShine, water & about 30-40 minutes, & they were all nice & shiny.

Gently poured off the dirty water first. Then I dumped the pins & brass in my Dillon separator, and used clean water to rinse AND allow the pins to fall into the tub. After many good rotations of the separator,, I pulled it out,, and shook it until almost all the water was out. Then, into a second tub of clean water. A good second rinse,, and tumble.
My first run removed all but (1) pin. And that was with (2) separate batches of brass.
After shaking off the excess water from the second rinse,, I poured them into a container,, to transport them to a dry towel,, where I spread them out, folded the towel over them, and let the towel absorb a lot of the water.
I then, moved them off the damp area of the towel, and allowed them to air dry a bit. Later,,, I placed them into a dry cardboard box lid,, and spread them out to allow even more drying.
This morning,, I took a magnet, and carefully & slowly run it over all of the pins. Not a single pin was found.
Upon all that,, I shook them around in the box lid,, and poured them across a few containers a bit. Still no pins.
They are now ready for my next step.

So, as they sit in an open dry tub,, I went to cutting cores for them. I still have a bunch to cut & swage to the correct weight. Once I have a bunch done,, I'll be adding them to the jackets.