For those of you that like to do it yourself here is a recipe for liquid case cleaner that works really well, I've been using it for 10 years or so and its really {frugal} to make.
It will not damage your brass.
Here is a recipe for cleaning grungy brass,
1 quart of water
1 cup white vinegar
1/2 cup lemon juice
1/4 cup liquid laundry or dishwashing detergent
I use a net bag to place brass in and dip it into cleaner and let soak for 20 to 30 minutes, aggitating every 5 minutes or so. Rinse with water and towl dry, I usually tumble for 2 to 4 hours after.