I’ve tumbled both nickel and non-plated brass. I haven’t run into any issues with nickel brass in particular. Did it have something to do with the nickel reacting with the stainless steel? If so, you may avoid that by removing your brass from the tumbler when it’s finished. I can’t see the cases getting discoloured over the course of a two-hour tumble session—unless it has something to do with the pH of your wash.
The only trouble I run into is when my wet tumbling wash is too far from a neutral pH. Recently, I’ve taken to doing a preliminary wash with a heavy degreaser, which I’ll let run for 20mins-ish. I’ll dump that water and flush with clean water. I’ll then let the brass tumble with a little Dawn detergent for a few hours. It has really helped with case discolouration caused by the dark oily film that seemed to be plaguing my brass.
The only trouble I run into is when my wet tumbling wash is too far from a neutral pH. Recently, I’ve taken to doing a preliminary wash with a heavy degreaser, which I’ll let run for 20mins-ish. I’ll dump that water and flush with clean water. I’ll then let the brass tumble with a little Dawn detergent for a few hours. It has really helped with case discolouration caused by the dark oily film that seemed to be plaguing my brass.




















































