Walnut is my choice. It is tougher and lasts longer then corn cob. I haven't tried rice and won't. I just want my brass clean and it certainly doesn't need to be new looking. Wet stainless pins just look like a lot of fiddling around for no gain.
If my brass isn't really dirty I clean it chemically. I only do small batches any more and a plastic jar, hot water to start with, lemon juice concentrate and a little dish soap to cut any oily residue. Put everything in the jar, screw the lid on, and shake vigorously and let it sit for a while. I usually leave it soaking with a shake now and then for 4-5 hours. Then I rinse in a mesh basket, dump the brass into a heavy steel pan, and sit it on my outside worktable and let the sun dry it. One whirlwind convinced me to to use a steel instead of aluminum pan. Time invested might be 20 minutes but probably less.