Re: Walnut and comet cleanser in tumbler
The pins are very small - small enough to pass though the flash hole and get inside the case. They don't scratch the brass. The tumbling action is very gentle it's not like they are being blasted. It's more of a rubbing action.
I use 5 lb of pins, 1 tablespoon of cascade, 1 teaspoon of lemon cleaner, and one gallon of cold water. I load either 250 - 9mm cases or 200 - .40 S&W cases. You need to keep the total weight of pins, water, and brass to around 15 lb. I tumble the .40 S&W for 4 hours and the 9mm for 6 hours. The larger diameter cases of the 40's allow more pins inside and they clean up faster.
After tumbling I spread them out on a pizza pan with 2 layers of paper towels for drying. I put mine in the oven on the lowest temperature setting and let them dry for about 1.5 - 2 hours. You could also let them air dry it just takes longer.
I know I'll catch a lot flack for this, but I don't like the idea of cleaning brass with corn cob or walnut shells. Both of those contain a lot of fine dirt and abrasives. I could be wrong but unless the brass is cleaned after cleaning I think it's likely one is trading burnt carbon on the cases for dirt. That kinda defeats the purpose of cleaning.