BTW... I did work my way up to a couple cc's of crystalized citric ( it is powdered, not liquid ) & a couple seems to clean better than a single scoop
The citric acid isn't supposed to be the main cleaning agent. I'm not surprised you're having to use so much of it to get the cases clean, especially if you're reducing the amount of dish soap at the same time.
Any kind of tarnish means that you've lost at least *some* of the metal - the black residue on your cloth after you polish silver is just an oxide of silver, for example. That doesn't mean that you've removed enough of the material to matter - it might just be a micron or two that have been removed from the surface.
But do a search for "Tarn-X" and "pink brass" and look at the results, keeping in mind that Tarn-X is nothing more than a citric acid solution with a little bit of fine clay for abrasiveness. I think the acid-based cleaners may remove a disproportionate amount of zinc, leaving behind the pink copper.
Basically, if your brass is tarnished at all before you polish it up, you've lost some metal, by definition. That doesn't mean that the brass is unsafe to use. But I also don't think that you're doing your brass any favors by cleaning them in a strong acid solution. Let the stainless pins do the work, add in an appropriate amount of soap to make a slightly caustic (not acidic) solution to help the pins along, and then a dash of citric acid for sparkle.