For a little while, very little while, I cleaned brass with soap and water, dryed in the oven, and polished by hand with steel wool. That got old really quick, and I ended up with a few splinters of brass or steel wool in my fingers.
Of the tumblers that were getting good reviews, the Cabela's model and the Berry's were two of the cheapest. With the exception of external appearances, the two are really the same. Berry's makes the tumbler for Cabela's.
I believe that the instructions that came with the Cabela's tumbler said to fill it 2/3 with media, and then load in the cases. The cases seem to come out cleanest and nicely polished when the tumbler is completely filled, and the motor doesn't seem to mind the full load. You don't have to fill it, obviously, but that's how I get the best results.
I run the tumbler 3 hours with a timer. Once-fired brass, if not too badly tarnished, comes out nice and clean. I probably don't need to tumble the once-fired brass from the indoor range the full three hours, and should probably cut that back in the future. The cases I reload with TiteGroup powder sometimes get scorched, and the tumbler doesn't remove that burn mark. I don't think that much of anything would remove the burn marks.
I store my cases in 1 Gallon Zip-Loc type bags, and the tumbler will hold about a half gallon worth of brass when filled 2/3 with tumbling media.
Although I'm not sure when I received it, I ordered it on 2/5/2007, and it's still going, knock on wood. When I first got it, I didn't have a whole lot of brass, and I was doing a lot of small batches, so I've got a good number of hours on the unit.
450 .223REM or .357Magnum
When/if you add liquid or paste polish to your tumbling media, run the tumbler for about 30 minutes without any brass. If you put in the polish and the brass at the same time, all the polish will end up caked into a few pieces of brass. It's not good, trust me on this. If you were tumbling bottlenecked rifle cases, you might have to throw out the pieces with polish and tumbling media stuck in them.
Get yourself a dust mask. The tumbling media will pick up lead from the primers in the cases, and you don't want to breathe that in. Besides the lead, dumping the media into a sifter will generate a lot of dust that you'll choke on anyway.
Run your tumbler outside or in your garage where any lead that might get out of it won't contaminate your living space. The motor in the tumbler can get hot, so don't put it on anything that might melt or ignite, like nylon carpeting or newspaper.
Cabela's Website - It's the model 400 tumbler. Check RetailMeNot for coupons.
Berry's Mfg. Website - Model 400 tumbler.
WARNING: Vibratory tumblers have been known to attract graboids. Use at your own risk.