How new are the primers?
I had a batch of CCI primers around for about 20 years. When I loaded and fired them, one showed a black ring on a load I was working-up at a charge weight that should not have been more than 25,000 psi. So, it really made me think.
Eventually, I deprimed and took a good look at the primer cup. There was a fine, but distinct crack from the edge up to the radius, which caused the leak. No brass or steel cutting, probably because it was a low-pressure load. The same crack in a full-power rifle load would probably have looked like the OP's pictures.
I think MY primer problem was that they were old, and probably had not been properly annealed during manufacture, so that they embrittled with age. So far, only one has failed. But, I have relegated them to 16,000 psi loads, so that isn't saying much.
SL1
I had a batch of CCI primers around for about 20 years. When I loaded and fired them, one showed a black ring on a load I was working-up at a charge weight that should not have been more than 25,000 psi. So, it really made me think.
Eventually, I deprimed and took a good look at the primer cup. There was a fine, but distinct crack from the edge up to the radius, which caused the leak. No brass or steel cutting, probably because it was a low-pressure load. The same crack in a full-power rifle load would probably have looked like the OP's pictures.
I think MY primer problem was that they were old, and probably had not been properly annealed during manufacture, so that they embrittled with age. So far, only one has failed. But, I have relegated them to 16,000 psi loads, so that isn't saying much.
SL1