5 String,
If you clean your cases in some dissolved
citric acid (an old Frankford Arsenal brass cleaning formula is 5% by weight, but it's more than is necessary for one cleaning), it will remove both salt traces and oxides without harming the brass. Absent that, a few drops of dishwashing liquid in water is likely to do about as much for the salt. Either way, rinse off afterward and set it on an old towel for three days or so to dry.
I don't know how much of the TW52 you have, but I'm at least slightly concerned about contaminating tumbler media with salt, though it would be awfully dilute. It's probably not going to be an issue, but I don't see the value in conducting the experiment if you don't have to, and the soapy water or citric acid solution will remove all doubt.