Bought my first tumbler in '83(?) and it's still going strong.All these methods will clean the brass and make it pretty,but I wouldn't put it in the washing machine or the dishwasher [emoji33]
Me too. A dash of NuFinish car polish really shines them up.I clean my brass by tumbling using "lizard Litter" bought at the local pet shop. About $10 for a very large bag.
Couple of used dryer sheets absorbs most of the dirt and dust.
No scoring in any of my cylinders from crud on the brass.