Have tumbled a few thousand pieces of large rifle brass through my Frankford Arsenal Platinum rotary tumbler with lovely results. However, the last few batches of .30-06 have come out only "reasonably clean", some tarnish, and not nearly as 'golden' as my initial batches.
Since I never strain all the SS media out of the drum, merely the water and then fish the brass out by (gloved) hand, I figured the decline must likely be due to a gradual accumulation of fine powder residue, lead dust, oxides, etc. etc. I thought I'd experiment by adding a cup (250ml) of Spray Nine degreaser and and two cups of water with a touch of dish soap. An hour later, I was somewhat surprised when, upon draining, the water was the darkest, sludgiest I'd ever seen. Perhaps some residue over time clings to the inner lining of the rubberised drum? I mean, nothing sticks to the SS pins.
Anyways, my next batch of Barnes tipped .30-30 came out glistening like new again. Anyways, food for thought.
