These cases are all the same head stamp. I am loosely assuming these cases are Browning brand ammo cases because of what looks like an antler on the head stamp. I was using RCBS case cleaning solution so I decided to clean few more tonight and this time I used my old stand by, Lemi-Shine and Dawn and sure enough there was another black case in there. Same head stamp. Anyone have any idea why these would turn black in a ultrasonic cleaner? Of any other head stamps, the Nichol plated brass all stay shiny white.