I just used "cold blue" with a cotton swab to quickly "draw" a circle of blue around my new .44 Special brass. It makes a nice blue mark that will not fade. I just rotated the swab around the brass up close to the case neck; after each ten, I used a wet paper towel to stop any further chemical action, then a paper towel with acetone to make sure things are completely dry, then blew the finished 100 cases dry for 30 seconds with a leaf-blower.
I considered marking the base of the case and said no. I want the case to be identified while I'm in the loading process, including adding powder. If I later put a .44 Special case in my maggie by accident, no harm done.
I label all of my ammo boxes anyway, so if the brass base is the only part of the case that's visible, that's okay.
Sonnytoo