One more idea on the ultrasonic cleaning approach ... I just got a Food Dehydrator from Harbor Freight for $25 and I use it to dry the cases after cleaning. The temperature never gets much about 160F so there is zero chance it will affect the case hardness/temper. So, instead of waiting hours or overnight for the cases to dry you can put them right into the dehydrator and in about 15-30 minutes the cases are nice a dry. Depending on the size cases you should be able to do at least a few hundred at a time and perhaps as many as 1000.
Brian
Brian