Vinegar is a little known secret weapon against rust. I use white vinegar to remove the plating on hardware that I need to weld on. There are some things to know though;
It will remove most plating (zinc, cad, nickel, etc.) given enough time.
Parts removed from vinegar need to be rinsed in clear water, pronto!
These parts will flash rust before your eyes if you do not immediately dry them and then treat them with some sort of oil etc.
You will smell vinegar for a while afterwards. The better job that you do rinsing, the less this will linger.
If you forget about some parts soaking in vinegar and come back in a month do not expect them to be usable. I think you might guess how I know this......
Was it me, I'd soak in PB Blaster or similar penetrating oil, and then use a toothbrush size Stainless bristle brush. Align your strokes with the grooves of the knurling on the dies.