You would want to be 100% sure of your identification. I cannot count how many times I had a round that I thought was one thing only to find out that it was something else completely.
If you really need ID, use sharpie, or something that wipes off in case of a mistake in the ID
even ink pen shouldn’t use on cartridges case ,it can damage the lacquer or even the brass
honestly never write on a cartridge ,but use an external identification system
Put the special ones in a plastic tube
For that you need and ‘engraver eraser’ tool - quite hard to find, uh huh.
Savage - While it might be a touch overkill, there is such a tool. They’re called “grinders”. They give better results on plate 1/4" or more thick! (Disclaimer - please, guys, don’t even consider taking me seriously) :-)
Yes, stencils are also no option! :-)