I have been using them in a Lee Loadmaster progressive, they have been working fine up till a week ago. My bud and I were at the range and we started getting rounds that wouldnt fire. Sent them around again in the M15 and they popped off. Next one that didnt fire we pulled out of the cylinder before we sent it back around. There was only a small dent. So it seems that 5-8 out of 100 pack seemed to be harder. I remembered back to when they were loaded (about 3 days) and recalled a change in the color of the white trays they came in inside the brick. Instead of being a nice pure white, they looked slightly yellowed. Perhaps they had been sitting in the wrong storage situation. I have another 3-400rds that was loaded that night with them, so I will be taking them back to the range to see how far back these (possible hard) primers are going to go. These were the older blue and white CCI boxes, not the newer style almost all dark boxes.