Not worth keeping it. I would suggest you scrap it. Wet tumbling cartridge brass is a thin line when done correctly, but dezincification IS a thing and there is a reason the solutions sold are buffered. There are some very ignorant posts in this thread. Some will (again) get mad and call BS, but I work on this kind of thing professionally.
Take a read, then decide: https://www.nace.org/Corrosion-Central/Corrosion-101/Dezincification/
Take a read, then decide: https://www.nace.org/Corrosion-Central/Corrosion-101/Dezincification/