I am trying to load 6 Dasher brass that has been fired 10 times. This is Lapua brass. I just full length sized the brass and then tried to set primers. I'm using CCI 450s. The load isn't hot and has never shown any pressure signs. In all the times this brass has been fired, the primers went easily and my hand priming tool(s) always easily bottomed out and the primers were seated perfectly. I've always used CCI 450s. This time, most of the primers were extremely hard to seat. They went in for the most part easily but didn't sit below flush. Then I had to adjust the primer seating depth by 5 thous and use a lot of force to seat them properly. I'm wondering what's going on. Nothing has changed so has the brass become hard? I would have expected the primer pockets to loosen after all these firings.