Its not necessary but if you aren't going to de-prime first you really need to dry the cases right after in a dehydrator, sun, oven, in front of the fire... whatever suits you. I used to not de-prime and I would just spread the brass out on a towel to dry but I found when I reloaded the brass primers were getting stuck in the pockets. This may not be an issue if you load soon after you tumble.