Howdy
I have been loading and shooting cartridges with Black Powder for over 20 years. 45 Colt, 45 Schofield, 44-40, 44 Russian, 38-40, and 45-70.
You do not need to get the inside of the cases super clean.
My method is to dump the spent brass into a jug of water with a little bit of dish soap dissolved in it. No vinegar, nothing fancy. If not dumped in water within 24 hours, the brass will turn green with brass oxide. Dump them in right away and no problem.
Rinse the brass over and over again with clean water until the rinse water runs clear. That's all there is to it.
After rinsing I let my brass air dry, then I dump it into my tumbler with Lizzard Litter (crushed walnut shells) and tumble it for a couple of hours.
Yes, my BP brass does remain slightly stained. I have always said that stained brass shoots just as good as shiny brass, it is just more difficult to find in the grass.
After tumbling there is always a light powdery residue inside the brass. Always. It does not matter. I go ahead and reload my brass, the powdery residue inside the brass does not make any difference at all.
Here is a jug full of 45 Colt and 44-40 brass at the end of a Cowboy match. Notice the water is dirty with suspended BP fouling.
A bag of Lizzard Litter from a big box pet store. The same stuff as crushed walnut you can buy on line, but much cheaper.
A bazillion clean cases. Notice I said clean. Just because the brass is stained, does not mean it is dirty. The BP fouling has been rinsed away. Not shiny, stained, but clean.
A batch of 44-40 loaded into brand spanky-new cases. They will never be this shiny again.
A batch of 44-40 loaded into stained cases. I don't know how many times this batch has been loaded, I stopped keeping track long ago. When they start to split I throw them away, other wise they get loaded again. Yes, there is a little bit of powdery residue inside every case. It does not matter at all. I prime the cases, dump in the powder, seat and crimp a bullet.
If you want shiny brass, you might try the pins. I have been doing it this way for over 20 years and don't care about shiny brass or brushed out insides. Waste of effort in this cowboy's humble opinion.