Home Forums Hunting & Shooting Ask The Gunwriters Has anybody ever seen this before?

I noticed that a handful of pieces of the 100 brass were discolored after the most recent firing. I've never seen this from a bolt gun before, after thousands and thousands and thousands of rounds fired. It kind of looks like the "burned" discoloration you sometimes see on pistol brass. This is Alpha 6mm Creedmoor brass. The brass has been fired 4 times, and never displayed anything like this before. When I annealed it, the color became darker almost instantly, and quickly traveled down the neck, shoulder, and body of the case. I was able to scrub off the discoloration with extra fine steel wool. It's not normal, loose soot as is sometimes seen around the neck of an underloaded cartridge, but it almost seems like soot that has been plated onto the case. And the colour only shows partway around the case, not the entire circumference. The rifle and ammo has performed as expected, with no abnormalities.

Case on left was fired in the rifle. Cases on the right were annealed after firing. On the right there is a normal case after annealing, as well as a few of the discolored pieces after annealing. Has anybody seen this before?




And one of the discolored cases after annealing...