my wife and I have been playing around with XD-M 5.25s, hers in 9mm and mine in .40S&W. Pistols are easy to tell apart as mine has a stainless slide and hers is black. I decided to make the mags easy to differentiate as well, so I lightly buffed them with a greenie, cleaned real quick with alcohol swabs, then applied 3 coats of Krylon Fusion (hers in pink, mine in blue). While all of that was curing, I went back and filled in the engraving (again color coded). Works like a charm and if it gets chipped, a quick going over with the greenie, a quick clean, then another shot of Krylon. It holds up pretty well.