when i bought a 7BR XP-100 new in 1980, i also bought forming dies and loading dies. playing around one day i formed about 50 old 30/06 brass to see if i could make them shoot with the large primer pocket and compare to the small primer pockets. thats just me...fast forward many years and i found them sitting just waiting for me to get with the program. i decided to color the large primer pocketed some how and i did it with DEF fluid...you thats right DEF ! i de greased the cases then put DEF fluid in a large pill bottle and left them a couple weeks before peeking...they needed a bit more time.....so i added a week. they look slightly camoflaged now with a random pattern. still smoothe no different feeling at all, and after several fireings still look pretty good. i assume that just sitting them upright in a shallow tray would do the same thing. i hope this helps someone who dosent want to buy brass black.