I just loaded some NEW mag-tech,(CBC), brass, 44 mag. Put it through my Dillon 650. I left it set-up exactly like it would be if the brass was fired, sizer, expander and all. I noticed it didn't like to come off the expander/powder funnel. A spritz of RCBS case slick into the case feeder solved that, sizing was easier as well. It needed to have the inside of the cases lubed a bit.
In another loading session, loading some 357 sig brass that I got from Midway. It was primed new PMC brass. Since this brass requires lube, like any other bottle necked brass, I backed the sizer way out as to not touch the brass. I didn't want to take the chance of killing the primers, OR having to move the decapper on a Hornady die!
I figured the powder funnel/expander would round-out the mouths that were a bit out of round, it did.
Normally all I do with any new brass is pass the expander through the brass with the die backed out a bit, so as not to have to lube them. This makes the dinged, out-of-round mouths round so it can be inside chamfered IF NEEDED. Bulk rifle brass from remwinchester, I also check the length, trimming if necessary.